encom discover 3d complete training workshop

8/2/2019 Encom Discover 3D Complete Training Workshop

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ENCOM DISCOVER 3D

COMPLETE TRAINING

(WORKSHOP)

Compiled By E.P


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Table of Contents i

Table of Contents

1 Introduction.............................................................................................. 12 Discover 3D Data Formats...................................................................... 33 Discover 3D Menu in the 2D Environment ............................................ 74 Discover 3D Interface.............................................................................. 9

The 3D Interface........................................................................................ 9Navigating in 3D...................................................................................... 10Exaggerating the scale............................................................................ 12View Modes............................................................................................. 12Menus...................................................................................................... 13Workspace Tree ...................................................................................... 13Inserting datasets.................................................................................... 163D Session File ....................................................................................... 16Properties Dialogs................................................................................... 16Display 3D Axes ...................................................................................... 183D Cursor Plane...................................................................................... 19Feature Toolbar....................................................................................... 20

5 3D Raster Images .................................................................................. 23View Map in 3D ....................................................................................... 233D Display Wizard................................................................................... 24Overlay Image on Grid ............................................................................ 25Insert Image directly into 3D.................................................................... 25Georeferencing Wizard ........................................................................... 26Multi Section Creator............................................................................... 26

6 View Vector Data as 3D DXFs .............................................................. 29

Import 3D Vector File .............................................................................. 29Import Objects from Table or Selection................................................... 30Creating 3D Extrusions ........................................................................... 31

7 View 3D Point and Line Data ................................................................ 33View 3D Point Data ................................................................................. 33View 3D Line Data................................................................................... 35

8 Gridded Surfaces .................................................................................. 37What is a Surface Grid? .......................................................................... 37Configuring Grid File Formats ................................................................. 39Create Surface Grid ................................................................................ 40

Input Tab ............................................................................................ 41Modify Grid Appearance.......................................................................... 43Assign Grid Values to Vector Layers ...................................................... 45Surface Profile over a Grid or Contour Plan............................................ 46Contouring a Grid File ............................................................................. 48Grid Query using Multiple Ranges .......................................................... 49Convert Grid to New Grid Format............................................................ 51Importing a Grid Surface ......................................................................... 51Clip Grid................................................................................................... 52


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ii Encom Discover 3D Workshop Manual

Reproject Grid ..........................................................................................54Gridding Geochemical Data.....................................................................54

Inverse Distance Weighting ................................................................58Kriging .................................................................................................61

Grid Calculator .........................................................................................61Gridding Geophysical Data ......................................................................63Filtering a Surface ....................................................................................64List of Available Grid Utilities....................................................................65Displaying Surfaces in 3D........................................................................66

9 2D Drillholes ...........................................................................................71Introduction...............................................................................................71Steps to Create Drillhole Sections ...........................................................72Drillhole Data Format ...............................................................................73

Collar Table.........................................................................................73Downhole Survey Table......................................................................73Downhole Data Tables........................................................................74

Create Drillhole Project ............................................................................75Data Validation.........................................................................................77Create Drillhole Sections and Plans.........................................................79Display Downhole Data on Section..........................................................82Create Drillhole Colour Pattern ................................................................84Using the Drillhole Section Manager........................................................86Adding a Drillhole Section to a Layout.....................................................88

Extracting Maximum and EOH Assay Values for a Drillhole ..............89Drillhole Log Display.................................................................................90Digitizing Boundaries and Exporting to 3D DXF ......................................92Calculating Sectional Resources .............................................................93Data Compositing.....................................................................................94

Compositing by Unique Attribute ........................................................95Compositing by Cut-off Grade.............................................................96Compositing by Elevation and Downhole Depth.................................96

Calculate 3D Coordinates ........................................................................96Drillhole Project Management..................................................................96

10 3D Drillholes ...........................................................................................97Drillholes...................................................................................................97Drillhole Sections......................................................................................99Drillhole Logs......................................................................................... 100Drillhole Selections................................................................................ 101Display Downhole Data......................................................................... 101Section Boundaries ............................................................................... 107

11 Voxel/Block Models............................................................................. 109Opening a Voxel Model......................................................................... 109Voxel display options............................................................................. 110Import and Export of Voxel models....................................................... 112Creating a Voxel model......................................................................... 113

Examining the data distribution........................................................ 114Gridding numeric data...................................................................... 115Gridding geological data .................................................................. 117

12 3D Digitization and Solid Generation ................................................ 119Digitization............................................................................................. 120Feature editing ...................................................................................... 121

13 Example exercises .............................................................................. 123


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Table of Contents iii

14 Movie Making....................................................................................... 1253D Fly-Through Animation .................................................................... 125

How Fly-Through Animation Works ................................................. 125Create 3D Fly-Through File................................................................... 127

General Playback Options ............................................................... 128Add capture points and event details ............................................... 129Output Formats ................................................................................ 131

15 3D Printing and Output Options ........................................................ 133Print Directly from Discover 3D............................................................. 133Export 3D View as Raster Image.......................................................... 134Add 3D View to MapInfo........................................................................ 134Save to Package ................................................................................... 1343D Workspace File ................................................................................ 135

Appendix A Menus and Toolbars................................................................. 137File Menu............................................................................................... 137View Menu............................................................................................. 138Insert Menu............................................................................................ 138Tools Menu............................................................................................ 139Utilities Menu......................................................................................... 140Main Toolbar.......................................................................................... 141Data Objects Toolbar ............................................................................ 141

Workshop Notes ............................................................................................ 143


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Discover 3D Data Formats 3

2 Discover 3D Data Formats

The Discover 3D module comprises both a Discover 3D menu within the2D/MapInfo interface, as well as its own separate 3D interface/window. Theseallow a 3D display to be created both from datasets already open within 2DMapInfo/Discover interface, and/or by opening applicable data directly into the 3D

window. This allows a large range of data formats to be created and supported byDiscover 3D.

Images

The content of any map window open within MapInfo/Discover can be displayedwithin the 3D environment as a geo-located image, using the View Map in 3Dmenu option. This produces a .PNG image with an accompanying .EGB file(georeferencing header file). All data sets visible in the map window (e.g. grids,images, vector data) will be incorporated into the image. The images RL can beassigned manually, or it can be draped over a gridded surface (e.g. a DEM grid).Drillhole sections and Drillhole Logs can also be displayed as images using theView Sections and View Logs options.

Images can also be directly opened and georeferenced in the 3D window, usingthe Georeferenced Image Creation Wizard. This wizard supports .BMP, .PNG,.TIF, .GIF and .JPG image formats. Images with an existing .EGB file can also beopened directly from within the 3D window.

A lot of data can be easily displayed in 3D as an image, but the data cannot bemodified or interrogated.

DXF/Vector Objects

MapInfo vector data such as points, lines and polygons can be displayed inDiscover 3D as DXF files. The View Objects in 3D menu option allows any vector

dataset open in MapInfo to be converted into a DXF file and placed into the 3Denvironment. This could include infrastructure (roads), contour lines (created froma gridded surface using the Surfaces>Contour a Grid menu option) or orebodyboundaries interpreted on drillhole cross sections (display in 3D using the ViewSection Boundary option).

Existing DXF files (eg the output from modelling programs) can be opened directlyinto Discover 3D via a number of menu options, or by simply dragging anddropping the DXF from Windows Explorer.

DXFs are a very efficient way of displaying a large amount of vector data,particularly points and polylines; however they have limited display options.

Points/Lines

Point data in MapInfo tables can be displayed in Discover 3D as 3D Lines or 3DPoints. These display types directly reference the source MapInfo TAB file, andproviding powerful display controls. These include point labelling, colour, size androtation modulation by data values, offset controls and support for True Type fonts.Examples of these display formats:

Colour modulating regional geochemical point datasets

Displaying prospect scale geochemical data as lines offset by an assayvalue (eg Cu) above a DEM surface.


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4 Encom Discover 3D Workshop Manual

Displaying flight lines coloured by date.

Displaying data in 3D as Points or Lines therefore gives the user a great deal ofdisplay control and options; however instigating these options on large datasetscan severely affect 3D rendering performance.

Gridded Surfaces

Grids created using either the Discover>Surfaces menu or other products (egtopographic or geochemical surfaces in formats such as Geosoft, ER Mapper,Surfer etc.) can displayed in Discover 3D either directly or via the View Surface in3D menu option. A large range of grid types are supported. Support is alsoprovided for the draping of ER Mapper ECW and .ALG files.

Drillholes

Drillholes present in an open Discover Drillhole Project can be displayed inDiscover 3D using the View Drillholes menu option. Alternatively, the relevantcollar, survey and downhole data .TAB files can be opened directly into Discover3D if they are assigned to a Discover Drillhole Project. The display of 3D drillholes

can be modified by colour and thickness modulation, as well as labelling andannotation options.

Images of cross-sections and drillhole logs created in Discover can also bedisplayed in 3D. Interpretative linework digitized into cross-sections can beexported into 3D as DXF objects.

Discover 3D can also directly open Geosoft drillhole databases (usually with asuffix .GDB).

Drillhole Selections

A selection from a drillhole project (eg all downhole intervals with Au>50ppb in a

subset of drillholes) can be displayed as a DXF file in Discover 3D.

Voxel Models

Discover 3D can create, display and manipulate Voxel block models (eg IPresistivity), supporting formats such as UBC, CEMI, and Noddy, as well aspreliminary support for Datamine, Surpac, Vulcan and Gocad Voxet.

Feature Database

Points, polylines and polygons can be digitized and attributed directly into the 3Denvironment as part of a Feature Database. Additionally, dxf vector or MapInfoTAB files can be imported as feature database objects, and then edited from within

the 3D environment. This allows the geoscientist to create interpretations in the 3Denvironment using all relevant datasets (eg drillholes, geochemical and/orgeophysical grids, voxel models, etc) without the being limited to traditional 2Dcross-sections.

3D Symbols

Point data in MapInfo .TAB or .MIF format can be directly displayed in Discover 3Das individually sized and orientated 3D Symbols.


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Discover 3D Data Formats 5

Movies and Fly-Throughs

The Fly-Though Wizard allows the creation of both Encom .FLY files for reusewithin the 3D environment, as well as .AVI movie files.


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Discover 3D Menu in the 2D Environment 7

3 Discover 3D Menu in the 2D Environment

To open the Discover 3D menu in the 2D MapInfo/Discover interface selectDiscover>Discover 3D. This will place a Discover 3D option on the MapInfoProfessional menu bar.

Discover 3D Menu Options

The Discover 3D menu allows a range of data types open within theMapInfo/Discover environment to be displayed in the 3D environment. It containsthe following functionality:

Open 3D Window - Open Discover 3D program from MapInfo/Discover

Open/Save 3D Workspace - Open or save 3D Workspace. A 3D workspacesaves the current MapInfo and Discover 3D session into a single workspacefile.

Refresh All 3D Data Update data in MapInfo/Discover and send changesthrough to Discover 3D without having to close down.

View Map in 3D Display a MapInfo map window view as a georeferenced3D bitmap image.

View Objects in 3D Select vector objects from a MapInfo map windowand view as 3D DXF vector file.

View Surface in 3D Display a gridded surface open in MapInfo inDiscover 3D.

Create 3D Points - Display geochemical/geophysical data as 3D points.

Create 3D Lines - Display geophysical/survey data as 3D lines.


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View Drillholes - Display drillholes in 3D. This option loads the entiredrillhole dataset.

View Sections - Display drillhole sections as georeferenced 3D bitmapimages.

View Logs - Display drillhole logs as georeferenced 3D bitmap images.

View Section Boundary Display section orebody or lithologicalboundaries as 3D DXF vector files.

View Drillhole Selection - Display only selected drillholes in 3D. This optiondoes not load the entire drillhole dataset.

3D Display Wizard Display an entire map window view or objects from atable through an easy-to-use wizard interface.

3D Extrusion Wizard - Extrude 2D bodies in 3D to aid in visualisation offault planes, veins or mine infrastructure.

3D Utilities Use the Multi Section Generator to register multiple imagesas sections using a series of lines or points. Use the Overlay Image on Gridto drape a raster image over a gridded surface using the original rasterresolution.

Toggle Auto 3D Selection - Turn the Auto 3D selection option On or Off.

Options Various user-defined system and display settings to customiseDiscover 3D such as temporary directory location, surface display andcompression options, XYZ indicator, map projection, images resolution, etc.


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Discover 3D Interface 9

4 Discover 3D Interface

The main screen items of Discover 3D

To open the Discover 3D window, select the Discover 3D>Open 3D Windowmenu option from the Discover 3D menu in the 2D MapInfo interface. The 3Dwindow will open after a short time.

Alternatively, the Discover 3D window can be accessed when a mappable MapInfotab file is open in MapInfo/Discover by using the appropriate View option from theDiscover 3D menu or by right clicking on a displayed MapInfo Professional mapand selecting View in 3D

The 3D Interface

The 3D window is divided into six areas:

The Main Menu items contain the operational pull-down menu controls.

A range of buttons within dockable Toolbars are available for controllingvarious functions (e.g. navigation, inserting objects etc.). Some of thesebecome active only when certain operations or data events are undertaken.

A Display Window area that initially contains a white background. This areais used to display windows and dialogs.

A Status Bar at the base of the screen to indicate processing and displayevents, the 3D Navigation Cursor or 3D Cursor coordinates, progress barand other useful progress information.


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Right mouse button with vertical movement zooms the image in or out ofthe display. The numeric keys (1-0) can be used to control the zoom speed,with 1 & 2 applying the slowest zoom speeds and 9 & 0 the fastest.

Left and Right buttons depressed with cursor movement allows positioningof the view point in the X/Y plane. Moving the cursor horizontally pans theview (moving the view point left/right), whilst moving the cursor verticallymoves the view point in a fly-through operation.

Keyboard entries with mouse manipulation can also be used to control 3Ddisplay operation. Available combinations include:

SHIFT key plus pressed left mouse button repositions the view point in thevertical axis and screen plane (this only operates in Navigate 3D mode).Holding the cursor near the view point reduces the speed of panning.

CTRL key plus pressed left mouse button repositions/rotates the image viewwhilst maintaining the current eye position. Nearer the centre of the viewreduces the speed of panning.

Reset 3D View restores the 3D display to a default such that the first displayedobject is centred and shown within the window.

The Page Layout buttons are designed for use mainly within the Page Layoutview. The Zoom In and Zoom Out controls allow adjustment of the overall zoomratio of the page display, whilst the Pan button enables you to position the cursorin a display window and roam the view. These can be used within the 3D View,but the 3D Navigation control is recommended.

The Fit to Page button is only available in Page Layout view, and automaticallyresizes the page to fit to the extents of the view.

Note If you have a mouse with an active wheel, you can also use this for zoomoperations. This is only recommended for use in controlling the Page LayoutView, not the 3D View.

While either the Page Zoom In orZoom Out options are being used, you canhold down the SHIFT key and the opposite effect is invoked. For example, if youZoom In and hold down the SHIFT key, the cursor changes to the Zoom Outcursor and has the opposite (Zoom Out) drawing effect.

The View Direction toolbar is used to automatically align the view to the selected

direction North, South, East, and West or Upwards or Downwards.

Selection of any of these four buttons rotates and aligns the Discover 3D view tobe along the direction selected. For example, clicking the N button orients theview to be looking to the north.

These buttons orient the view to be viewed Upwards or Downwards along the Z(vertical axis).


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Exaggerating the scale

Bounding Box dialog

For Global scaling changes, the 3D Map Properties dialog contains optionsincluding:

Add a title to the map window in Page Layout mode

Display a bounding box around the 3D data in the map window

Display colour and size legends when in Page Layout mode

Apply directional or ambient lighting to map window display

Apply scaling to map window in XYZ direction

Scaling of individual datasets can also be applied via the relevant Property dialog.This is particularly useful when preserving real world height values (e.g. DEM gridsand drillholes), but exaggerating for example geochemical/geophysical grids.

View Modes

The Discover 3D display window varies in appearance depending on the ViewMode. Two view modes are available:

Normal Mode This is the default viewing mode. In normal mode, Discover3D displays the 3D objects using all the available area of the display windowand provides the most efficient view of data.

Layout Mode In Layout mode you can see how objects are positioned onthe printed page. This view is also useful for editing borders, margins and


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the placement of objects prior to printing. The size and orientation of thepage is defined by printer settings specified in the File>Page Setup option

You may switch between Normal and Layout views quickly by using the PageLayout button or from the Window menu option.

Menus

Discover 3D contains the following pull-down menus; most of the menufunctionality is duplicated in the related Toolbars:

File - File handling for project sessions and access to external databases iscontrolled using the options on this menu item. Setting of printing and exitingare also available.

View - Options to display the various view modes, toolbars and controldialogs, status bar and property dialogs.

Insert Permits graphical objects to be inserted into existing 3D map

window displays. These menu commands are also duplicated on the DataObject toolbar.

Features Import and Export of vectors in feature databases including DXFfiles,

Tools Provides options and customisation of Discover 3D settings. Alsoprovides access to tools such as Grid Flipper.

Help - On-line help and reference facility.

Utilities Additional Discover 3D add-on modules including Fly-throughWizard, Solid Generator and DXF utilities.

See Appendix A for full descriptions of menu items.

Workspace Tree

The Workspace Tree is the main means of control used in Discover 3D. TheWorkspace Tree operates by listing ALL objects shown in a display. These entitiesare listed as a hierarchy with various tree branches.

The Workspace Tree is also replicated in the DiscoverEnhanced Layer Control(ELC), automatically adding 3D window icon (in addition to the present Mapper andBrowser icons) with all relevant branches listed beneath it. This mirrors the

functionality of the Workspace Tree, except for a few submenu options.


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Rightmousebuttoncontrolon

Menudisplay Optionsavailable

3DMapBranch

Display properties of the 3D Map or anysubordinate branches. Add axes or addadditional data objects such as drillholes, rasterimages etc. Open the Fly-through Wizard.

DataObjectBranch

Properties and Delete options are available.

Relates to all DataObjects

SurfaceBranch

Properties and Delete options are available.The Grid Flipper tool can also be accessed.

ColourLegendBranch

Properties and Delete options are available.The Data Limits can be reset, and a Size Scaleadded.

FloatingColourBar

Properties and Add options are available.


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Inserting datasets

Data Objects allows addition of various data types to 3D view.

3D Session File

Sessions and project management is controlled by the File>Open Session, SaveSession and Save Session As items. Discover 3D uses binary session files tosave and restore projects. Within the session files the following information isstored:

Path(s) to the necessary data source information.

Path(s) to any used object, raster and bitmap files.

Path(s) to drillhole databases.

Configuration data for open windows and components, their attributes andproperties.

Session files are usually saved with the file extension .EGS.

The session files do not contain data, objects or bitmaps. Consequently, if asession is opened but the data or object access is not available, the software willnot be able to restore the session completely. A message is displayed in thiscircumstance indicating which source file is unreadable.

Session file restoration has a lost file recovery mechanism. If Discover 3D cannotlocate some data or other necessary files, it alerts you and offers the option of

browsing for them. This applies to all component file types that may have beensaved with the session. The following message appears.

Message displayed if a component of a session file cannot be read

In the event that the requested file is not available, from the Open File dialog,select the Cancel button and the session will continue through its list of files torestore what it can. If other files are not accessible, the above message isrepeated.

Properties Dialogs

From the Workspace Tree every branch can have its properties controlled byeither:


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Selecting any branch in the workspace tree and click the right mouse button.The Properties menu item accesses the relevant Properties dialog.

Double click the relevant item in the Workspace Tree with the left mousebutton.

Select the Workspace Tree branch and then click the Properties button.

In most cases, the Properties dialog has tabs displayed at the top. Each tabcontrols a separate aspect of the item selected.

The Properties dialog and assorted tab controls

If the Auto Apply option is disabled, changes to properties are not made until theApply button is clicked. This is a useful feature that enables changes in varioustabs of a Properties dialog to be setup before they are applied (particularly forlarge datasets where redraw times may be significant). If a mistake is made whileentering changes, select the Restore button to return the control settings to theiroriginal state. In contrast, enabling the Auto Apply option will apply any changesimmediately. Property changes can also be applied by clicking the OK button,

which will also close the dialog.

Each object branch in the Workspace Tree has a Show/Hide check box. To turnof the visibility of an object branch in the 3D display window uncheck the


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3D Cursor Plane

The 3D Cursor Plane mode allows the user to identify the 3D coordinates of any

point in the 3D window. Clicking the Show 3D Cursor Plane button will displaythe default Cursor Plane location surrounded by a bounding Focus Box.

3D Cursor plane display with bounding box, 3D Cursor crosshairs (red) and associated coordinates in

the bottom right

Use the Select /Navigate button to enable the 3D Cursor within the plane (defaultdisplay is red cross hairs). Moving the mouse will move the crosshairsaccordingly, with the corresponding X, Y & Z coordinates for the crosshair positiondisplayed in the status bar (bottom right of the 3D window). This mode isparticularly useful for aligning the cursor plane with imaged cross-sections. Theselected images name is displayed at the bottom left of the 3D Window. With theSelect button enabled, use the mouse to rotate the view and the mouse wheel toalter the zoom.

Alternatively, use the 3D Navigation button to control the view, reselecting theSelect button when finished to display the crosshairs.


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The orientation of the cursor plane can be controlled via the options below.

Up / Down ()keyboard cursor

/arrow keys

Controls the dip of the cursor plane (rotates it about a line located in the XYplane)

Left / Right ()keyboard cursor

/arrow keys

Controls the azimuth of the cursor plane (dip is constant)

PageUp / PageDownkeyboard buttons

Shifts the cursor plane laterally (plane is kept parallel to but shifted left or right (orup or down) from its current position, maintaining dip and azimuth)

Switches the cursor plane between the X, Y and Z planes.

Bonds the cursor plane with that of the selected georeferenced image.

Locks the cursor plane in its current position when editing features.

The Toggle Transparency Clipping button allows all data in front of the cursorplane to be made transparent, allowing a clear view of the data intersected by the

plane.

Shrink

Enlarge

Fit

The Focus Box provides a 3D visual reference for controlling the cursor plane. Itcan be resized using the Shrink and Enlarge buttons, or resized to the currentview using the Fit button.

The Edit Cursor Plane Properties button enables the appearance of the cursorplane and focus box to be adjusted.

Options include:

Line colour and thickness

Cursor plane fill colour and opacity

Display of the 3D cursor as either 2D or 3D crosshairs

Manual input of parameters to control the cursor plane position andorientation

Focus box size

Feature Toolbar

The Features toolbar provides the controls for the creation, editing and selection ofFeature Objects onto the Cursor Plane. This enables the user to digitize points,polylines and polygons directly into the 3D environment to create objectsrepresenting geological interpretations, orebody outlines, faults and alterationzones for example. The Feature Objects can then be used in the 3D SolidGenerator utility to create a 3D solid by interpolating between each object.


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A Feature database (cosmetic or created) must be editable for the Feature toolbarto be enabled. The following controls are available:

Confirm New Feature - Option to display a dialog after each feature object iscreated to enable input of attribute data.

Select Feature - Create a selection region to select all Feature Objects thatintersect or lie within this region. This selection region is independent of theCursor Plane. It is drawn in the screen plane and will select all objects below it.The selected object attributes are listed in the Data tab of the InformationSheet.

The Select/Navigate mode on the Zoom Controls Toolbar can also be usedto select individual objects. Used in tandem with the keyboard CTRL keyenables the selection of multiple Feature Objects.

Create Point - Digitise a point symbol by clicking with left-mouse button at thedesired location on the Cursor Plane.

Create Line - Digitise a polyline on the Cursor Plane by clicking on a series of

discrete points or holding down the left mouse button and moving the mouse tocreate a continuous curve. Double click to complete the polyline.

Create Polygon - Digitise a polygon on the Cursor Plane by clicking on aseries of discrete points or holding down the left mouse button and moving themouse to create a continuous curve. Double click to close the polygonbetween the first and last points.

Edit - Display and edit nodes for a selected object. Select individual nodes forediting using the Select/Navigate mode on the Zoom Controls Toolbar.Delete selected nodes by pressing the keyboard Delete button ormove aselectednode by holding down the left mouse button and dragging it to a newlocation.

Activate Elasticity - When this option is enabled and a selected node ismoved to a new location neighbouring nodes are moved as well. Elasticity isconfigured via the adjacent pull-down arrow. The Radius controls whichneighbouring nodes are affected by the move. This dialog also containsoptions controlling how the affected nodes are moved - this affect isrepresented graphically next to each option (Gaussian, Square, etc).

Feature Information - Similar in function to the Select/Navigate tool. Ifmultiple objects exist at the cursor location the objects are displayedindividually in the Data tab of the Information Sheet (i.e. the Data tab displaycycles through each object, rather than listing all object information at once).


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Snap to node Allows the current objects node (new object or editing anexisting object) to be snapped to an existing objects node. Upon activation,the cursor will change to a circle in the middle of the cross-hairs; when thecursor is close to an existing node, it will change to the standard cross hair; leftclick to snap to this node.

To the right of the Snap toolbar button is a pull-down options dialog. Thisallows the Pixel Tolerance to beset (i.e. how close the cursor needs to be toan existing node before it can be snapped to that node). A high-pitched audibleBeep (dee) can also be enabled for when the cursor is within the set pixeltolerance, when the cursor moves outside the tolerance, a low pitched doh willsound. The Duration of these beeps can be set in milliseconds.

Further keyboard/mouse combinations can be found under the Click Tips tab ofCursor Plane Properties dialog.


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3D Raster Images 23

5 3D Raster Images

View Map in 3D

Any data displayed in a MapInfo map window can be visualized in the 3Denvironment as a georeferenced bitmap image (*.egb) i.e. a correctly positionedraster image. This is a very simple and quick way of displaying a lot of data in 3D,however the data is displayed purely as image pixels; any data attributes are lost(e.g. soil copper values) and individual object and datasets properties cannot bealtered (e.g. line or point colour and styles).

The Discover3D >View Map in 3D option opens the Discover 3D Map Wizard,from which the desired map window is selected. The 3D Surface sub-window hastwo options for the height (z) attribute of the output 3D image; either a fixed height(flat) option, or selection of a grid file over which to drape the image. Right clickingin an open mapper and selecting View in 3D will open the same dialog without theneed for map selection.

Exercise 5.1 Import a MapInfo map window view into 3D

Data Location: Training 3D\Topography and Training 3D\Geology

1. With Discover running, open the CopperHill_AMG55_AGD66.TAB,Geology_fill.TAB and Geology_lwk.TAB files into the same map window.

2. Note that the extents of the grid are significantly larger than the geologyvector information. If this grid is used to drape the geological information in3D, the resulting .egb file would encompass the extents of the largest inputdataset, in this case the grid file. To prevent this, draw a polygon in the

cosmetic layer encompassing just the vector data, select it and clip the gridto this polygon (use the Surfaces>Grid Utilities>Clip tool). Call theresulting grid CH_Topography_Clip.

3. Add the geological layers to the new map window with theCH_Topography_Clip grid. Turn the visibility off for the grid, and resize andzoom the mapper window so that the Geology view fills the map windowdisplay

4. Right click within this mapper window and select the View in 3D option. Inthe View in 3D dialog, select the Grid option, and ensure that theCH_Topography_Clip file is selected in the adjacent drop-down box. ClickOK. Note that the Discover3D>View Map in 3D menu option can also be

used.

5. Discover 3D will open in a separate window, and display the geologyoverlying the topographic surface.

6. In the Workspace Tree to the left of the main view window, double-click onthe 3D Map branch to open the 3D Map Properties dialog. This allows theglobal control of various 3D attributes. For instance under the Scale tab,adjust the Z axis scaling using the slider to accentuate the vertical scaling ofthe image. Click Apply to apply the changes.


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7. To navigate around the 3D display, click the 3D Navigation button in thetoolbar. Hold down the left mouse button and move the mouse to rotate theview about the viewing centroid. Hold down the right mouse button andmove the mouse up and down to adjust the zoom aspect. Holding downboth mouse keys allows movement of the viewing centroid in the X-Y plane,whilst holding down the SHIFT key allows movement of the viewingcentroid in the Z plane.

8. Right-click on the 3D Axis branch of the Workspace Tree and select theProperties option. This opens the 3D Axis Properties control dialog, inwhich the axis display options can be adjusted. Under the Ticks tab,deselect the Show ticks on the axis planes only option and click Apply.Alternatively, unticking the 3D Axis branch will make the axis invisible. Thiscan be useful for printing, when having a grid in the background clutters thedisplay (e.g. of drillholes).

9. Right-click on the main Images branch in the Workspace Tree and selectDelete Images to remove the geology raster from view.

Note The output image quality is dependent on the map window size: a larger map

window zoomed to the extents of the dataset will result in a higher resolutionimage in Discover 3D. The screen resolution can also be increased to improve thequality of the output image, by selecting the Display tab of theDiscover3D>Options menu item, and increasing the Create Raster Images atvalue (default value of 2x). Note however that this will increase the size of theoutput image, thereby reducing the redraw speed within the 3D environment,particularly when viewing multiple images.

3D Display Wizard

The 3D Display Wizard can also be used to import a map window view.


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3D Raster Images 25

Exercise 5.2 Import a MapInfo map window view using 3D Display Wizard

1. Re-position the map window used in Exercise 1 to show a different view andselect the Discover3D>3D Display Wizard menu option.

2. Use the wizard to select the underlying grid file and open the image into a3D window.

3. Close the Geology_fill and Geology_lwk tables and delete the Imagesbranch from the 3D Workspace Tree.

Overlay Image on Grid

The Discover>3D Utilities>Overlay Image on Grid utility is specifically designedto drape existing raster images over a topographic grid and view in Discover 3D.

Exercise 5.3 Import into 3D an airphoto image draped over a topographic surface.

Data Location: Training 3D\Topography

1. Open the Airphoto.TAB and CopperHill_AMG55_AGD66.TAB files into thesame map window. Resize and zoom the mapper window so that theAirphoto view fills the map window display.

2. Select the Overlay Image on Grid option from the Discover3D>3D Utilitiesmenu and note the path of the Output EGB file.

Insert Image directly into 3D

Images can be imported directly into an open 3D window if they already are in EGBformat. EGB images can be added using the Insert>Images menu or the AddImage button from the Data Objects toolbar.

When either of these options is selected within a 3D window an Image branch isadded to the Workspace Tree. Right-clicking on this branch and selectingProperties opens the Image Properties dialog, from which a georeferenced bitmapimage can be selected.


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Insert menu

Data Objects Toolbar

Exercise 5.4 Display an Image EGB file from Discover3D


1. Select the Add Image button from the Data Objects toolbar within Discover3D to add an Image branch to the Workspace Tree.

2. Right-click on this branch and selecting Properties opens the ImageProperties dialog.

3. Browse to Training 3D\Topography directory and select the Airphoto.egb filecreated in Exercise 5.3. Note that colours can selected to be imported as

transparent which is useful if an image has, for example, black or whitespace around it when it was captured. Alternatively, apply a transparencyfactor to the whole image or offset the image by a set distance from the DTMgrid.

4. Close all data sets in the 3D window.

Georeferencing Wizard

An existing non-EGB image can also be georeferenced by using the ImageRegistration Wizard within this dialog.

Multi Section Creator

Multiple scanned regional cross sections (eg those accompanying geologicalsurvey 1:250,000 interpretive geology maps) can be easily displayed correctlylocated in 3D, provided they are accompanied by a table of polylines tracing theX/Y extent of each cross section.


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3D Raster Images 27

Exercise 5.5 Create and display multiple georeferenced regional cross sections in 3D

Data Location: Training 3D\ Geology\Regional Cross Sections

1. Drag and drop the FactGeol_DTM.egb into the 3D window. This representsthe fact geology in zone 54 of South Australia (data courtesy of PIRSA).

2. Open the CrossSection_Extents.TAB file into MapInfo as both a browser anda map window. This table contains multiple polylines representing the spatialextents of 9 scanned regional cross-sections, as contained within the datadirectory. Note that each polyline has the following information: a sectionname (directly referencing a PNG image file), a top and a bottom RL value.These fields are compulsory for the process to function correctly.

3. Select the Discover 3D>3D Utilities>Multi Section Creator to open thistool.

4. Ensure that the various dialog boxes are populated as below. Note that theFormat option indicates the source image type, in this case PNG images.This tool can only process one image type at a time. The type optioncontrols whether a single EGB file is created for all sections, or whether aseparate EGB file is created for each section. Click OK.

5. Browse in Windows Explorer to the output directory, and drag the newlycreated crosssection_extents.egb into the 3D window.


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View Vector Data as 3D DXFs 29

6 View Vector Data as 3D DXFs

DXF files (Data Exchange Format) are a proprietary but widely used digital fileformat (ASCII or binary) for describing 2D and 3D spatial vector data, developed byAutodesk Corporation. They are a very efficient method of displaying large point,line or region datasets within the 3D environment; this is however at the expense of

colour modulation.

It is recommended to display data such as gridlines, infrastructure (roads,streams), contour lines and flight lines as DXFs rather than images, which are farmore memory intensive and have fewer display options.

Import 3D Vector File

From within the Discover 3D window, existing DXF files (eg the output from amodelling program) can be displayed using the Add Vector button orInsert>3DVector menu option. The following exercise gives an example of their use.

Exercise 6.1 Import various 3D DXF vector files.

Data Location: Training 3D\Structure

1. Select the Add Vector button from the toolbar and double-click on thenewly added Vectors branch in the Workspace Tree to open the VectorsProperties dialog.

2. Under the File tab, click the Open File button and open theInterp_Structures.dxf from the above data location. Under the Transparencytab, adjust the Transparency slider to a suitable level and click the Applybutton to view the changes. Readjust as necessary.

3. In the Surface tab, enable the Override fill colour options for a number ofcomponents, and adjust these in the adjacent colour boxes. Click OK tofinish.

4. A quicker method for importing DXF files is simply to drag the file fromWindows Explorer into the Discover 3D window. Try this using theIsosurface.DXF file from the Geochemistry folder.

5. Remove all Vector branches when finished.


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Import Objects from Table or Selection

MapInfo vector data such as points, lines and polygons can be displayed inDiscover 3D as DXF files using the Discover 3D>View Objects in 3D menuoption. A separate Vector branch is created for each dataset within 3D window,allowing each dataset to be coloured separately.

Exercise 6.2 Display selected map objects as 3D vectors.


1. Open the CopperHill_AMG55_AGD66.TAB grid andRivers_AMG55_subset.TAB into a map window. Also open theStreams_Mol_subset.TAB from the Geochemistry folder also into thiswindow.

2. Select Discover 3D>View Objects in 3D to display the View objects in 3Ddialog. Highlight the Rivers_AMG55_subset table. In the Assign Z valuearea tick the From grid option and select the surface grid from the Grid pull-down list. Click OK to display in 3D.

3. Use the View Objects in 3D tool to display the Streams_Mol_subset.TAB in3D. Note that this table already has an RL field; use this as the Z value byticking the From field option (and deselecting any other options) andselecting this field from the pull-down list. Click OK to display in 3D.

4. Within Discover 3D, open the 3D Map Properties dialog (double click on the3D Map branch), select the Scale tab and exaggerate the scale display tobetter visualize the topography.

5. Note however that the stream samples cannot be labelled or have their

symbol display altered (size or colour modulation). This is covered in thenext topic.


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View Vector Data as 3D DXFs 31

Creating 3D Extrusions

MapInfo vector data can be extruded to form solid 3D DXFs. For instance, a mapof the surface traces of a series of faults could be extruded by a fixed distanceunderground to visualise these faults at depth, perhaps in tandem with a drillholesubset. A MapInfo table of polygons representing building outlines could beextruded by values in a building height field, and perhaps coloured using a type

field.

The Discover 3D>3D Extrusion Wizard menu option enables all map objectswithin a MapInfo table to be displayed in Discover 3D as a 3D Vector/DXF file.

Exercise 6.3 Extrude the selected fault trace map objects as solid 3D vectors.

Data Location: Training 3D\Structure

1. Open the Prospect_Structure.TAB and DEM_5m.tab grid into a mapwindow.

2. View the table in a browser window. Note the Dip_Dir, Dip and Generationfields. These will be used to control the orientation and colouring of theoutput DXF objects.

3. Select the Discover 3D> 3D Extrusion Wizard. Tick the Enable sun-sampling in input data option in Step 1 of the Extrusion Wizard dialog, andclick Next.

4. In the Step 2 dialog, ensure the Primary Z value is set as 0, and tick thePlus grid value option. Use the open file button to browse for theDEM_5m.ers grid file located in the Training 3D\Topography directory.Click Next.

5. In the Step 3 dialog, set an Extruded Z value of -200, and tick the ZRelative to Primary Z option. Click Next.

6. In the Step 4 dialog, enable the Specify an Azimuth and Dip option. Tick theUse Azimuth Field option, and set this to the Dip_Dir field. Tick the Usedip/tilt field option, and set this to the Dip field. Click Next.

7. In the Step 5 dialog, enable the Modulated by field option, and assign thisthe Generation field. Choose a Colour table eg pseudocolour. Click Next.

8. Click Apply to display the output DXF in the 3D Window. Doing so will keepthe Extrusion Wizard dialog open allowing changes to be easily made and

reapplied. Clicking OK will apply changes and close the dialog.

9. Double-click on the Vectors branch in the 3D Workspace Tree to open theVectors Properties dialog. Alter the Transparency, and apply the changes.


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Viewing 3D Point and Line Data 33

7 View 3D Point and Line Data

View 3D Point Data

The Discover 3D>Create 3D Points option requires an open MI point data table,in which each record has an X (Easting), Y (Northing) and Z (RL) field. If a pointdataset does not have a Z/RL field, but a topographic surface grid field exists forthe data area, use the Surfaces>Assign Values from Grid option to assignelevation data.

Specify the desired points dataset in the following Show 3D Points dialog. A*selection* option is also available for the display of a previously selected (in a MImapper) smaller subset of the main dataset.

Right-clicking on the Points branch in the Workspace Tree in the 3D Window willaccess the Properties option. The Points Properties dialog allows the display ofthe points dataset to be altered through field and symbol selection, applyingtransforms and decimation.

Exercise 7.1 Display geochemical sample data as points. Modulate their colour and size, applylabels and set scaling and offset factors.

Data Location: Training 3D\Geochemistry

1. In MapInfo, open thecombined_soilsamg.TAB file.

2. Select the Discover 3D > Create 3D Points option, and select this tablefrom the list. Click OK to display in the 3D window.

3. To colour the point symbols by copper values in Discover 3D, double-click

on the Points 1 [combined_soilsamg.TAB] branch in the Workspace Tree.This will open the Points Properties dialog. Select the Symbols tab, tickthe Modulate Colour option and select the Cu field in the adjacent drop-down window. In the Legend/Lookup Table drop-down window below this,select the DHAssay_Cu table, and click Apply.


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4. To vary the size of the symbols based on a field values, tick the ModulateSize option in the Symbols dialog. Assign a field from the drop-down list (egPb), and enter an appropriate size range. Click Apply. Combined with theColour modulation set in step 3, this is an excellent way to apply bivariatemapping in the 3D environment (one attribute modulated by colour, the otherby size).

5. Labels can be quickly applied using the Label tab. Tick the Show Labelsoption, and choose the Cu field. Click the Format button, and set a ppm

suffix. Set a Label Skip Factor of 5 (1 in 5 labels will be displayed).

6. The Transform tab allows a Translation factor to be applied to the dataset.This is a useful way to offset the data from a surface grid to allow data of lowvalues to be made visible (eg with an offset of say 10m applied). Return toMapInfo, and with the DEM_5m grid table open, display it in Discover3Dusing the View Surface in 3D option (this option will be explained fully in thenext section). Return to the 3D window, and note the some data is obscuredby the surface grid. Go to the Transform tab of the Points Propertiesdialog, and select a Scale and Translation Transform from the pull-downlist. Assign a Translation of 3 and click Apply. Zoom into the point dataset;the data has now been moved a little above the DEM surface, and is nownot obscured by the surface grid. When finished, reset this to No transform.

7. Another useful way to view geochemical data is to set the assay value asan Offset. Go to the Fields tab of the Points Properties dialog. Set theOffset to Cu, and click Apply. This will display the data across a very long Zaxis. To alter the offset scale, click the Advanced Options button adjacentto the Offset field. Choose the Transform tab, and after selecting a Scaleand Translation transform, set the Scale as 0.2. Click Apply.

8. The Decimation tab allows the dataset density to be reduced for very largedatasets where rendering performance is an issue. Select the Fixed ratedecimation option, and set a value of 5 (i.e. 1 in every 5 points will bedisplayed). Click Apply.


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Viewing 3D Point and Line Data 35

9. In a similar fashion to the ELC, you can control the visibility of branches bydeselecting them in the Workspace Tree.

10. Use File>Close All to close all open 3D data.

The Add Points button adds extra point branches to the Discover3D WorkspaceTree. However it requires an open 3D point dataset (imported via the View Pointsfunction); it cannot import datasets into the 3D window.

View 3D Line Data

Line data generally refers to data that has been collected systematically alonglinear traverses with samples or measurements taken at discrete intervals. Thedata format is exactly the same as a point data table except whereas point data isdisplayed as individual points in Discover 3D, line data is represented by a singlelinear feature for each sample line. Line data tables require each record to have anX (Easting), Y (Northing) and Z (RL) field along with a line identifier field.Geophysical survey line profiles are an example of a line data file that can beviewed in Discover 3D.

Open a line data table into a map window. To view only a subset of the line datatable make a selection in the map window. The Discover 3D>Create 3D Linesoption will open the Discover Show 3D Lines dialog, which allows selection ofeither a lines dataset or selected subset thereof (*selection*).

The Add Lines button in the 3D window adds a Lines branch to the WorkspaceTree. Open the Lines Properties dialog by right-clicking on a Lines branch andselecting the Properties option. The Lines Properties dialog allows manipulationof the line dataset display, including labels, line style and individual line selection.However it requires an open 3D line dataset (imported via the View Pointsfunction); it cannot import datasets into the 3D window.

Exercise 7.2 Display geochemical sample data as Lines. Alter the appearance of the Linedisplay.

Data Location: Training 3D\Geochemistry

1. From the Training3D\Topography folder, open the DEM_5m grid andAirphoto files into a new MapInfo map window, and make the DEM_5m gridinvisible. Use Discover3D>View Map in 3D to drape the air photo over thegrid file in the 3D window.

2. Within MapInfo, note that the combined_soilsamg.TAB file contains a Linefield. Use the Discover 3D>Create 3D Lines option and select this table

from the list. Click OK to display in the 3D window. Discover3D will display aDefine Database Fields dialog prompting for the Line field. Assign the Linefield.

3. In the Points Properties Fields tab, assign the Cu field as the Offset.Again use the Advanced Options button and set the Scale factor to 0.2under the Transform tab. Click OK twice to apply this scaling factor.

4. In addition to the Points Properties tabs, the Lines Properties dialog has aLine Style and 3D Line Style tab.

5. The 3D Line Style tab controls the cross-sectional shape of the lines, andcan be particularly useful for representing infrastructure (eg pipelines). Tick


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the 3D Tube option, and select a Tube Shape from the list. Alter theThickness, and click Apply.

Custom tube shapes can be used via the Import New Shape option built intothe Tube Shape Manager found in the Utilities menu: this will import anyshape drawn in a MapInfo table.

6. Use File>Close All when finished.


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Gridded Surfaces 37

8 Gridded Surfaces

The DiscoverSurfaces module provides a rich suite of functions and tools forcreating and analysing gridded surfaces. The Surfaces module has been designedto integrate seamlessly with gridded data created externally from MapInfo and with

other Discover modules that use gridded data such as Drillholes.

What is a Surface Grid?

A surface grid is a rectangular array of points, each of which has an interpolated Zor height value. The Z value in a grid may represent either real heights (such astopographic elevation, depth to weathering or coal seam thickness) or mayrepresent a geochemical, geophysical or other value (such as gold concentration,radiometric total count or rainfall).

The surface grid is generated from a set of input points each of which have alocation and a Z value for that location. The regular surface grid is generated from

the irregularly distributed input points by calculating interpolated values at regularpositions.

It is important to understand that the interpolated values are approximations only ofthe real values of the surface and that the interpolated values differ dependingupon the interpolation method used. With some interpolation methods, it is possiblethat the interpolated value is slightly different to that of a data point at the sameposition.


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Regular grid of interpolated points generated from irregularly distributed input points

Once a regular grid of interpolated values has been calculated and stored, it canbe displayed in MapInfo. The grid can be displayed as a set of rectangularpolygons, each one representing a grid cell. The advantage of this method ofdisplay is that the MapInfo standard tools for thematic mapping and querying canbe used with the grid. Although Discover does allow grids to be created in thisformat, the major disadvantage is that of file size and display speed.

If the grid cells are stored in a simple binary format, then Discover can displaythem in MapInfo as a raster image. This method of display is significantly quickerthan for polygon grids and allows large grids to be handled efficiently.

A third way in which a grid can be displayed is as contours. Contours aregenerated by tracing lines of equal Z value across the grid. The contour lines donot provide as much information as a grid, but do offer another visualisationmethod. This is useful for displaying contours of one grid over a second grid (forexample, soil geochemistry contours over a magnetics grid).


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Gridded Surfaces 39

Configuring Grid File Formats

Discover>Configuration>Grid Handlers

When grid formats are created, imported or exported, the Discover Surfacesmodule can assist these operations by:

Creating grid surfaces in a preferred format

Exporting a grid in a preferred format

Internally using the preferred grid format to allow ease of use when MapInfois used with third-party software packages (such as ER Mapper, VerticalMapper, Surfer or Oasis Montaj by Geosoft).

The preferred grid format can be specified from theDiscover>Configuration>Grid Handlers menu item. Use the Grid FormatSelection dialog to nominate your preferred grid format.

Once a grid format has been selected, all grids created from this point use thespecified format unless an interface option exists to override the setting. You canalter the preferred Grid Handler used by Discover by selecting another at anytime.

The following industry standard grid formats are supported by Discover:

Band Interleaved by Line (*.BIL)

ER Mapper (*.ERS)

Geosoft (*.GRD)

Surfer (*.GRD)

Vertical Mapper (*.GRD)

ESRI ASCII Grid (*.ASC, *.TXT)

USGS DEM (*.TAR)

Minex (*.XYZ)


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ASCII (*.TXT, *.ASC, *.CSV)

Note The Grid Handler support provided in this option is ONLY available for MapInfoversions more recent that Version 5.5.

MapInfo Vertical Mapper creates raster-based format grids. A read/write handlerfor Vertical Mapper format grids is supplied with Discover. All versions of MapInfo

Professional 6.0 or later include a read-only handler.

Create Surface Grid

Discover can produce a gridded surface from any mapped data, which has anumeric column representing a z-value or grid channel. Examples of this type ofdata include topographic spot heights, soil geochemical sample results orgeophysical data such as ground magnetic, or gravity data. Discover can also gridline and polygon data providing there is an associated numeric z-value. Thereforeit is possible to create a grid directly from data such as contour lines without havingto pre-process the data first and convert the line information into points.

Exercise 8.1 Create an elevation grid from spot height data over the Darlot area

1. Open the DARLOT_SPOT table from the EncomTraining\Darlot\Topography folder and using the Information Tool, querya few of the spot heights to see the associated data. We will create a gridusing the AHD_RL field. The elevation values range from a low of 429.31 toa high of 528.6m. You can check this by selecting Query > CalculateStatistics and selecting the DARLOT_SPOT table and the AHD_RL field.

2. Select Discover>Surfaces menu. A new Surfaces menu should appear onthe MapInfo Menu Bar. Select Surfaces>Create Grid and select the

DARLOT_SPOT layer or right-mouse click on DARLOT_SPOT layer in theELC and choose Create Grid.

3. The elevation data is loaded into the DiscoverGridding Tool. This utility iscontrolled via a series of tab pages to the left of the preview window. Onloading the data Discover has automatically computed a set of griddingparameters, however we can modify these according to the data to begridded.


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Gridded Surfaces 41

4. Select AHD_RL from the list of numeric fields available to grid.

Input Tab

The Input tab summarises the input data and provides a selectable list of allnumeric data columns that are available for gridding in the source Tab file or query.Basic summary information is provided for the selected data including the numberof points, minimum and maximum field values and minimum and maximum easting(X)/northing (Y) values for the minimum bounding rectangle that fully encloses theinput data.

A Breakline table can be selected in order to force gridded data to conform tocertain slope requirements in critical areas, eg drainage traces, topographic ridgelines or roadways.

The Coincident points pull-down list contains a number of options to use in theevent that there are two or more data points at the same location.

The Data Conditioning option enables you to condition or annotate the data usedto grid. The input grid data can be clipped to specified extents, null values can beexcluded from the gridding process or converted to background values andminimum and maximum capping values can also be set.

Statistics Explorer

The Statistics Explorer is a utility for examining and understanding the spatial andstatistical aspects of a dataset. The Statistics Explorer will be examined in moredetail in the next exercise.

Preview Window

View input points in the preview window. Click button to remove input points fromview.

View search ellipse in the preview window. Only available if Inverse DistanceGridding method is selected.

Apply a histogram equalisation stretch to the image in the preview window. Thisbutton can be used to distribute colours more evenly across the image and isparticularly useful for data with poor dynamic range.


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Display images in the preview window as either coloured or monochrome (blackand white). This button toggles the image between monochrome and colour.

Apply a sun illumination to the image in the preview window. This can be used toenhance detail within a gridded image. The sun angle is fixed from the north-eastdirection.

Interrogate the quality of the interpolated surface using the Statistics Explorer.Select a look-up table to colour the grid. The chosen colour table will be applied tothe gridded image when loaded into Discover.

A pop-up menu can also be accessed by right-clicking with the mouse in thepreview window:

5. Click on the Method tab and select Triangulation as the method.

The Triangulation method produces a regular gridded surface through a set ofdata points by using an optimised Delaunay triangulation algorithm. The triangular

mesh is created by drawing lines between adjacent input data points and formingan irregular network such that no triangle edges are intersected by other triangles.A regular grid is then computed from the triangular irregular network and grid cellvalues computed using a natural neighbour interpolation process. As the originaldata are used to define the triangles, this method is very useful for situations wherethe data must be honoured very closely (eg elevation data in a digital terrainmodel).

The triangulation method is best applied to data that is evenly distributed over thegridded area. If there are large areas of sparse or missing data distinct triangularfacets may appear in the output grid. As triangulation uses all the input data toconstruct the triangular mesh, the only parameter that needs to be adjusted is thegrid cell size. Grid cell size can be adjusted to an appropriate value for the dataset.

6. Click on the Geometry tab and leave the default Cell size at 150m.

7. Choose the Output tab and select ERMapper as the output grid format.Save the grid to the same folder as the input data points and click Save tocreate the grid and open it into a new map window. Turn off the visibility forthe DARLOT_SPOT layer in the map window.

To report grid cell values directly to the screen, choose the Grid Info button fromthe Surfaces button bar.


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Gridded Surfaces 43

8. To view information about the grid select the Surfaces>Grid Informationmenu option.

Modify Grid Appearance

Exercise 8.2 Modify the appearance of a grid by applying a colour pattern, sun shading,

transparency and create a grid legend.

By default Discover applies a linear colour pattern whenever a surface grid iscreated or registered. A linear colour pattern applies each colour in the look-uptable to the same sized data range. This method of grid display is generallyadequate but in many instances it is desirable to modify the colouring of the grid.

1. Make sure the grid created from the DARLOT_SPOT table is open in a mapwindow.

2. Select Surfaces>Modify Grid Display

3. In the Colour tab select Histogram Equalization and chooseElevation.LUT from the Select Colour Table pull-down list.

Other available colour methods include:

Full Linear Stretch Apply a linear colour pattern to the grid between theminimum and maximum values. By default the minimum and maximum dataranges are selected but these values can be manually changed underOptions. To return to the original data limits click the Reset to Input Limitsbutton.

Auto-clip Linear Stretch Apply a linear colour pattern between the middlen% of the data. Choose from a 99.9% or 99% clip to remove high and lowdata values and prevent distortion of the grid display.


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Histogram Equalization Stretch Discover analyses the distribution ofdata in the grid and applies colours so that there are approximately equalnumbers of grid cells displayed in each colour. By default the minimum andmaximum data ranges are selected but these values can be manuallychanged underOptions. To return to the original data limits click the Resetto Input Limits button.

Check the Recompute Histogram box to distribute the colour table evenlyover the data range if the input limits are changed.

Percentile Range Break With geochemical data, it is often appropriate toshow the grid coloured into just a few ranges, based on the data distribution.For example, gridded geochemical data may be coloured with ranges of 0,30, 60, 80, 90, 95, 98 and 100%. Each of these ranges would be shown in adifferent colour to highlight the areas of interest.

Data Range Break Similar to percentile ranges, colouring by data rangesallows the grid to be displayed with a discrete number of colours, specifiedby data value rather than percentile value.

4. To set a grid transparency, use the Transparency Slider. Set this to 30%and click Apply to view the changes in the map window.

5. Click on the Histogram tab and view the data ranges and colour schemeapplied in graphical format. Experiment with moving the toggles to manuallyclip the data at Low and High values.

6. Click on the Sun tab and experiment with dragging the sun icon in thepreview window to a new angle and elevation. To view the changes in themap window either use the Apply button or check the Auto Apply box.


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Gridded Surfaces 45

To display an additional light source which may be useful when working withgeophysical grids select a Sun HighlightAngle and Elevation as well.

7. To display a grid legend select the Surfaces>Make Legend for Grid menuoption.

Assign Grid Values to Vector Layers

The Assign Values from Grid menu option assigns grid cell values from the grid

to map objects that overlie them. This is used, for example, to assign elevations tosample points or to drillhole locations from a digital elevation model, or to assignmean geochem values from a geochemistry grid to overlying geology polygons.

Discover can also assign minimum and maximum values to polygons from the gridcells that lie within the polygon. As well as assigning the values to columns, thevalues can be reported to the screen.

Exercise 8.3 Assign RL to stream sediment samples from elevation grid

1. Open the MAJOR ELEMENTS table from the EncomTraining\Darlot\Geochemistry folder.

2. Make sure this table is editable and add a new float column to the tablecalled Elevation. Select all the stream sediment samples in the mapwindow.

3. Select Surfaces>Assign Values from Grid

4. Assign value to column: Elevation

5. When processing has completed open the selection into a browser windowand observe the populated Elevation field.


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Surface Profile over a Grid or Contour Plan

The DiscoverDraw Grid Profile function provides a powerful tool for identifyingand analysing trends or spatial relationships on gridded surfaces. Profiles for anyline or polyline can be generated across gridded surfaces or contour plans.

A profile across a topographic, geochemical or geophysical data grid can beintegrated with vector information from polygon and line layers to allow therelationships to be interpreted.

Profiles for multiple surfaces may be displayed together to show, for example,topographic and base of weathering surfaces, together with magnetics and soilgeochemistry, with the surface geology and fault lines draped over the topographicsurface.

Exercise 8.4 Draw a profile over a grid and drape with geology

1. Open the GEOLOGY from the Encom Training\Darlot\Geology folder intothe same map window as the elevation grid.

2. Draw a line in the Cosmetic layer that extends over a portion of theelevation grid and make sure it is selected in the map window.

3. Select Surfaces>Draw Grid Profile. In the Profile Generator dialog choosethe DARLOT_SPOT_AHD_RL gridfrom the Profile from layer pull-downlist.


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Gridded Surfaces 47

In the Polygon Drape control check the Show polygon intersections inprofile box and choose the GEOLOGY table from the Polygon layer pull-down list. Use the CODE as the Polygon ID column.

Assign a profile table name and location and leave the other defaults. ClickOK to display the surface grid profile in a new map window.

4. Open the DRAINAGE table from the Encom Training\Darlot\Topographyfolder into the map window. Select the profile line in the map window againand re-create the profile only this time check the Show intersections inprofile for all selectable line/polyline layers in the map window box tosee where the drainage intersects with the elevation profile.

5. Close all tables apart from the DARLOT_SPOT_AHD_RL grid in the currentmap window.


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Contouring a Grid File

Discover can contour and label a grid and then export the contours as a 3D DXFfile. Contours can be coloured according to the underlying grid colours and also besmoothed. Regular contour intervals can be specified or contour intervals can beread from a text file. The upper and lower limits to contour between can also beset.

Exercise 8.5 Contour a grid, label contours and export the contours as 3D DXF file.

1. Open the DARLOT_SPOT_AHD_RL grid into a new map window if it is notalready open.

2. Select Surfaces>Contour a Grid.

Select the Contour Parameters forRegular Contour Intervals. Enter aminor contouring interval of10 with a major contouring interval of50.

3. Check the Contour Smoothing box.

4. Click on the Output Contour Table button and save the contours to a tablein the Encom Training\Darlot\Topography folder namedDARLOT_CONTOURS.

5. Select Surfaces>Label Contour Lines

6. Label the contour lines using the ZValue field. Place labels every 10 km andsave the labels into a new table called CONTOUR_LABELS in theTopography folder. Click OK to create contour labels.


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Gridded Surfaces 49

7. Select all the contour lines in the map window.

8. Select Export Grid File or Contours>Export Contours to 3D DXF fromthe Surfaces menu and click OK to create the DXF file called DARLOT

CONTOURS.DXF into the Topography folder.

Grid Query using Multiple Ranges

The grid query tools provide a convenient method of creating MapInfo polygonsthat cover the areas of the grid that meet the specified criteria. The grid cells canbe selected based on value or percentile and terrain grid cells can also be queriedbased on their elevation, slope and aspect. Terrain grids can return volumecalculations between a base level and the topographic surface.

Exercise 8.6 Select areas from a grid based on specific elevation ranges and display as avector layer

1. Select Surfaces>Grid Query>Select by Multiple Value Ranges and enterin the following values and colours.


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2. Save the polygons to a new table in the EncomTraining\Darlot\Topography folder and click OK.

See also the Surfaces>Grid Utilities>Classification utility to create aclassified grid instead of polygons.

3. To determine the volume of the grid which is located above the 500 RL levelselect the Surfaces>Grid Query>Calculate Volume for a Grid menu

option.

Note the result is displayed on the screen in a message window.


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See also the Surfaces>Grid Utilities>Volume utility to calculate a volumebetween two gridded surfaces.

Convert Grid to New Grid Format

Selected grids can be converted to an alternative grid format including:

ERMapper

Geosoft

Vertical Mapper

Surfer

GeoTIFF

Arc ASCII Grid

Exercise 8.7 Save elevation grid to new grid format

1. Select Surfaces>Grid Utilities>Convert menu option.

2. Click the Save As button and select Arc ASCII Grid File (*.asc) as the newgrid format. A _converted suffix is automatically added to the new gridupon export.

3. Click Save to create the new grid file.

4. Close all currently open grids and vector files.

Importing a Grid Surface

Discover can import and display the following grid formats: Banded Interleaved(*.BIL), ER Mapper (*.ERS), Geosoft (*.GRD), Surfer Binary grids (*.GRD),USGSDEM (*.TAR), Vertical Mapper grids (*.GRD) and Minex (*.XYZ). Discovercan also import grids in ASCII format including ESRI ASCII format.

The DiscoverSurfaces>Import Grid File option provides a method that enablesthe user to check the grid header file during the import process.

When importing the grid files Discover will attempt to read the grid geometry

information from the grid file header. If Discover cannot access the grid geometryinformation it will check the grid file size, the number of cells and the cell size toensure that the grid geometry is valid. You can modify or enter any additionalinformation necessary in the registration dialog. When you import a grid file usingDiscover you are required to specify an appropriate MapInfo Projection for the gridfile so it can be correctly registered.

Exercise 8.8 Import ERMapper SRTM grid for Copper Hill project area

1. Select Surfaces>Import Grid File>ERMapper Grid.


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2. Browse to the Encom Training\Copper Hill\Topography folder, select thePROJECT AREA SRTM DEM 25M.ERS file and click Open.

3. In the ER Mapper Grid Registration dialog click on the CoordSys buttonand choose the Australian Map Grid (AGD84) Zone 55 projection.

4. Once the grid is created change the grid display colour from greyscale topseudocolour and apply a new Histogram Equalization Stretch.

Clip Grid

The Clip tool provides a simple method of reducing the size of the grid to cover justthe area of interest. Use this to reduce a large grid to just that covering a tenementfor reporting or data sharing purposes.

Simply select a polygon covering the area required to clip and choose theappropriate clipping type from the Grid Utilities dialog.

Clip Grid to Region - discard all grid data that lies outside of the selectedpolygon(s). If the selected polygon is not a rectangular shape, then theclipped grid covers the minimum bounding rectangle of the polygon with nullvalues in those parts of the grid outside of the polygon.

Blank grid underneath region - write null values into the area covered bythe selected polygon(s) while retaining the surrounding grid.

Clipping regions may be Polygonal orRectangle. Polygonal involves clipping to a

selected polygon or polygon file. Rectangle involves clipping by coordinates toreduce the size of the grid.

Exercise 8.9 Clip SRTM Grid to Tenement Boundary

1. Open the EL2290_CH_AMG table from the Encom Training\CopperHill\Tenements folder into the map window containing the imported SRTMgrid.


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2. Select Surfaces>Grid Utilities>Clip and choose EL2290_CH_AMG as thetable to clip against.

3. Select the Clip Grid to Region option and view the clipped grid in the Afterwindow.

4. Click the Save As button and enter a name for the clipped grid and save it tothe Encom Training\Copper Hill\Tenements folder.

The clipped grid is opened into a new map window. Note that for irregularclipping regions the grid cells are replaced as null values to the minimum

boundary rectangle of the clipping region.


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Reproject Grid

Surface grids can be reprojected between projected (UTM), geographic (Lat/Long)and custom coordinate systems. This operation relocates the various pixellocations in the grid through an interpolation method to match the requested outputcoordinate system.

Exercise 8.10 Reproject the clipped SRTM Grid to new coordinate system

1. Select Surfaces>Grid Utilities>Reproject utility. Choose the clipped gridcreated in the previous exercise and note the source projection.

2. Click the Choose button under the Target coordinate system window andselect Map Grid of Australia 1994 (MGA94) Zone 55.

3. Select an Interpolation Method from the following:

Bilinear the value of a grid cell in the new grid is assigned the weightedvalue of the four surrounding grid cells in the original grid

Bicubic uses the weighted value of 16 surrounding grid cell values in theoriginal grid to interpolate the value of a grid cell in the new grid. Requiresmore processing but is more accurate than bilinear interpolation andproduces a smoother grid.

Nearest Neighbour simple interpolation whereby the new grid cell value istaken from the closest grid cell in the original grid.

4. Click Save As and leave the default file extension _reprojected to save thereprojected grid to the Encom Training\Copper Hill\Tenements folder.

5. Close all currently open tables at the completion of this exercise.

Gridding Geochemical Data

Geochemical data can also be gridded in the same way as elevation data. Griddingby a particular element enables geochemical anomalies to be easily distinguishedfrom background values and also provides a means of interpolating valuesbetween sample sites.

Exercise 8.11 Use the Statistics Explorer to view data to be gridded and investigate the InverseDistance Interpolation method.

1. Open the COPPER HILL SOILS table from the Encom Training\CopperHill\Geochemistry folder.

2. Select Surfaces>Create Grid and highligh

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