3d laser scanning with modelmaker

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ModelMaker Basic Training Course

Prepared by 3D Scanners (UK) LtdApril 2003

Version 1.100

3D Scanners (UK) Limited 2003Reproduction and Distribution Forbidden


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Table of ContentsIntroduction........................................................................................................4

Technology......................................................................................................5Process Overview...........................................................................................6User Interface..................................................................................................7

User Interaction............................................................................................8Toolbars.......................................................................................................9ModelMaker Panes....................................................................................10New / Opening / Closing Files...................................................................11Scroll Bars..................................................................................................12Display modes...........................................................................................12Showing/Hiding..........................................................................................13

Introduction Review......................................................................................13ModelMaker & Arm Configuration ...................................................................14

Faro Probe Calibration..................................................................................15

Probe Identification....................................................................................15Initial Point Capture....................................................................................16Final Point Capture....................................................................................17Calibration Verification...............................................................................17Calibration Acceptance..............................................................................20

Sensor Alignment..........................................................................................22Parallel Plane Check..................................................................................26Alignment Verification................................................................................27

Set-up Exercise.............................................................................................28Set-up Review...............................................................................................28

Scanning..........................................................................................................29

Localiser Handling........................................................................................29Scanning Strategy.........................................................................................30

Sensor Orientation.....................................................................................30.....................................................................................................................32Scanning Preparation...................................................................................32Scanning Parameters...................................................................................33Sampling.......................................................................................................34Scan Menu....................................................................................................34Data Quality..................................................................................................34Scanning Exercise........................................................................................37Scanning Review..........................................................................................37

Datuming..........................................................................................................38Datuming Menu.............................................................................................38Datuming New Entity Menu..........................................................................39

Creating New Points..................................................................................39Creating New Lines....................................................................................41Creating New Planes.................................................................................42Creating New Spheres...............................................................................43Creating New Cylinders.............................................................................43Creating New Circles.................................................................................44

Interactive Creation of Entities Through the Datum Menu...........................45Measuring Entities:....................................................................................45

Required Points for New Entity Construction...............................................48New Point Creation Techniques Comparison...............................................49Co-Ordinate System Generation Methods...................................................50


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3-2-1 Alignment:.........................................................................................50Three planes:.............................................................................................51N Points:.....................................................................................................51Single plane:..............................................................................................52

Required Entities for Different Alignment Techniques..................................52

Alignment Viewports.....................................................................................53Transformation and Rotation of ANY Alignment...........................................53Datuming Exercise N Point Alignment.......................................................55

Datum Entity Extraction.............................................................................57Copying of Data into a Common Viewport................................................58Matching of Alignment Entities..................................................................59Application of the Transformation Matrix...................................................60

Datuming Review..........................................................................................61

3D Scanners (UK) Limited has worked to verify the accuracy of the information contained inthis manual as of its publication date: however: such information is subject to change withoutnotice and 3D Scanners (UK) Limited is not responsible for any errors that may occur in thisdocument.


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Introduction

The ModelMaker scanning system provides the first stage in many inspection,reverse engineering and multi media projects. Physical objects can be quickly

digitised in to thousands or millions of points in one coherent data set suitablefor many different processes.

This training manual has been designed to meet the following objectives: -

Enable user to set-up the ModelMaker scanning system.

Give the user an understanding of scanning techniques and approach toscan jobs.

Make the user familiar with datuming tools and methods

Give an insight in to data processing

In order to give all trainees an awareness of the system a brief demonstrationof the ModelMaker will be given by the course trainer. This will cover thefollowing points: -

x,y,z positions from localiser, image view from camera.

Navigation through menus with arm

Scanning of a part and capturing datum entities

Demonstration of sectioning



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Introduction

Technology

A laser line is projected onto the object. The line is viewed at an angle by acamera so that height variations in the object can be seen as changes in theshape of the line. The resulting captured image of the stripe is a profile that

contains the shape of the object. From calibration data for the sensor a depthmeasurement is then calculated from the profile. This process is known aslaser triangulation.

Laser triangulation is a relatively old technology; laboratories have been usingthis technique for measurement for over thirty years. Only in the last ten yearshave suitable computers for this work become cost effective to offer industrialportable scanning systems.

In order to synchronise the images taken from the camera with the correctarm positions there is a connection between the arm and the ModelMakerscanner (trigger cable) that provides the signal for this.

ModelMaker achieves more flexibility over other scanning systems by beingable to optimise the laser power for different coloured objects.

On the ModelMaker W range of sensors each time the camera captures aprofile 300 depth measurements are taken along the laser line. This processis repeated 25 times per second, enabling the system to capture up to 7500points per second.


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Introduction

Process Overview

In the flow diagram below a typical scanning job is described. Most jobs wouldfollow a similar route to the point of capturing the point cloud.After this point there are different options which are typically

driven by the downstream application for the data.


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Obtain brief for datause

Consider area

to be scanned

Ensure part is suitablysecured for scanning

Scan

Process data in to suitable format forend user. I.e. mesh, sample, cross-

section. (This could also includealigning separate scans.)

Export data in suitableformat

Inspection Reverseengineering

Theseprocessescould be

completed in athird partypackage


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Introduction

User Interface

ModelMaker has a typical windows based interface.

The diagram below shows the terminology for different parts of the viewport

used in ModelMaker.


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MenuOption

s

ToolbarButtons

ScanningControl Menu

Scroll Bars

Contextmenu RMB

Panes (Scanpane selected)


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Introduction

User Interaction

To offer the user a flexible efficient interface to the ModelMaker software thereare several different interface methods. The table below gives

an oversight to the different methods.

Mouse typical Microsoft left mouse button functionality is

used to navigate through menus. Menu lists will roll down,

left-click on the desired option to select. Right mouse button

is used to access the context menu.

Keyboard To open a menu option using the Keyboard,

press the plus the letter that is underlined in the

menu's title. You choose a menu selection by pressing its

underlined letter, or by using the cursor keys to highlight it

and then pressing .

Keyboard Shortcuts -A full list of the available shortcut keys

can be found under the help menu. For example Ctrl + S

will save the current document

Greyed Out Menus and Selections -Menus may be greyed

out when menu options are not applicable to the currentdata object or when there is no data object in the current

window.

Context Menu - These menus are available only in the

workspace and the entity panes. (Accessed through the

Right Mouse Button)

Arm and hand-switches The scanning control menu can

be operated by using the arm in association with the hand

switches. Button A is typically used to open or close a

menu. Any menus with > next to them can be expanded to

give more options.

The Escape key can be used to close any menu.


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Introduction

Toolbars

In the diagram below there is a description of the different ModelMaker toolbaricons. Where there is an arrow in the bottom right hand corner of an iconthere is an expanded list of commands; these are also detailed below.


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AlignSensor

Open File

RefreshView

SeeBelow

Save File

NewDocument

InvertSelection

Toggle FrontSelection

RedisplayLast Colour

Plot

ZoomWindow

Rotate

Zoom

Pan

SeeBelow

SeeBelow

Lasso Selection

Box Selection

Ellipse Selection

Pick Triangle

Pick Single Point

Pick Pair Points

Capture DynamicPoints

Capture StaticPoints


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Introduction

ModelMaker Panes

Panes offer more functionality than normal toolbars. The three panes inModelMaker all have different functionality.

Scan Pane Entities Pane Output Pane

Scan Pane is typically controlled through interactive use of the arm and handswitches. This works like a typical toolbar.

Entities pane the mouse is used to interact with this menu.

Allows you to work quickly on all data entities in a document, withouthaving to select them in the window.

Allows you to manage your data and the way it is displayed.

Entity operations are mainly performed using context menus (right clickmouse button).

Output pane

Records and results of different functions applied to the data sets arerecorded here. This information can be copied and pasted as inany text editors.


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Introduction

New / Opening / Closing Files

Toolbar buttons can be used to open any ModelMaker files the standardformat being .sab files. In order to create a new file from a scanned object the'new' document button can be used or alternatively by selecting Prescan fromthe Scan pane a new document is automatically opened.

All files should be saved in a suitable directory. When work is finished the fileshould then be saved and closed if continuing work in ModelMaker.

It is possible to have many files open in ModelMaker at the same time.

Display of multiple files can easily be controlled through the Window menu.

Zoom / Pan / Rotate.

There are three methods for zooming/panning in ModelMaker, Toolbar icons,Scroll bars or mouse functionality.

Toolbar icons can be used by selecting and then clicking and dragging withthe Left mouse button.

Mouse. ModelMaker recognises a three-button mouse. Use the following keycombinations to change the view.

Shift + Left Mouse Button RotateShift + Middle Mouse Button Zoom

Shift + Right Mouse Button Pan


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Introduction

Scroll Bars

Clicking on the bottom right button will change from Zoom and Pan view toRotate view:

Display modes

In the table below the various different display modes for different types ofentity are shown. In ModelMaker these are referred to as rendering modes.

Rendering mode Example Entity types applicable to

PointsScans/meshes, Polylines,

Points

Polygons Scans/meshes, Polylines

Flat Shaded Scans/meshes

Smooth shaded Scans/meshes


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1. Rotate around screen Z-axis2. Rotate around screen Y-axis3. Rotate around X screen axis

1. Pan left and right

2. Zoom in and out3. Pan up and down


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Introduction

Showing/Hiding

Changing the display mode of any entity can be done in two ways. This canbe done globally from the context menu in the workspace or alternativelythrough the context menu in the entity pane, shown here.

Introduction Review

Discuss these points with the course tutor

Technology parts of the sensor.

Interface methods. Context menus different functionality in different locations.

Possible display modes for different entities.

Changing display modes globally, for specific entities.


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ModelMaker & Arm Configuration

This section covers the set-up of the ModelMaker system. There are manyother considerations to be made when starting a scanning job; these will be

covered in more details later on.

How to connect the different parts of the system together is not detailed in thismanual. The course trainer will cover this thoroughly. There is also an onlineModelMaker help file that covers this in detail. Many users have colour codedstickers to assist set-up. This avoids unnecessary problems associated withincorrect connection of cables.

TipColour code all connections with stickers whilst the course tutor is present to

make future set-ups easier.

In order to obtain good scan results the most important part of the set-up isthe calibration of the Faro probe and alignment of the ModelMaker sensor.This section focuses solely on this. Pictures are used extensively to describethe various angles and settings required. Trainees may benefit from makingtheir own additional notes in addition to this.



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Faro Probe Calibration

The first stage once the equipment is assembled together is to complete aprobe calibration. This is easier to complete without having the sensorattached to the arm.

To do this we use the Single Hole Probe Calibration in the Faro software.(The screen shots shown here show the use of Caliper 3D, this can also becompleted in CAM2 or Anthro-Cam.)

Probe Identification


Check that this sizematches the probeattached to thearm.

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Initial Point Capture

The next step involves capturing a series of points using the buttons on thefront of the Faro arm.

Follow this series of images for the first 10 points.


Position 1 Hold(0.5sec)

Press front button

Press back button

The probe is now rotated through approximately 300for the next point to be taken.

Position 2 Hold(0.5sec)

Press front button

Press back button

This process of rotating the probeapprox. 300 and taking points iscontinued until point 11.

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Final Point Capture

Before continuing in the same manner for the next 10 points it is necessary toflip the arm through 1350.

Once all the points have been taken the results of this process will bedisplayed. The results show an average error. Even if this value is within theaccuracy of the arm it CAN NOT be assumed that the probe calibration isgood.

Calibration Verification

The next stage involves checking the probe calibration prior to continuing withalignment of the sensor. To do this we now use the ModelMaker software tocomplete this check.

IMPORTANTENSURE THAT FARO SOFTWARE IS CLOSED PRIOR OT OPENING THEMODELMAKER SOFTWARE.


Again repeat for points 12 20 rotating probe300 between capturing points.

1350

Position 11 AfterFlipping ArmThrough 1350 Hold(0.5sec)

Press front button

Press back button

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After opening a new document select the Capture Dynamic Points tool inModelMaker.

A similar process to the probe calibration is now performed.

Start and stop the capture of points by either using the remote hand switchesor foot pedals.


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1350

3600

3600

Start with the armin this position.

Start capture thenrotate the probethrough 3600 asshown

Stop capture at3600

Flip arm in tonew positionshown

Start capture thenrotate the probethrough 3600 asshown Stop capture at

3600

There will now be a cluster of points on the screen. Press Escape to

cancel capture dynamic point capture

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Calibration Acceptance

The next step is to analyze the results of this test.Select all of the captured points then fit a single point.

A result box will be displayed.

These results should be checked as follows: -


For Faro Goldarms the threedistances in thebox on the leftshould be belowthe 2-sigma valueshown on the right

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There is a second visual check that can be made on the data. The idealresults are shown below (these results are for a Faro Gold 8 arm)

In the event that the results are poor results similar to those below will be

seen. Here two separate clusters from the different arm orientations can beclearly seen.

IF EITHER OF THESE TESTS FAIL REPEAT STEPS 1-5.


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Sensor Alignment

Once the probe calibration is complete it is now necessary to complete thesensor alignment.

Always make sure that the certified settings check box is ticked.Enter the sizes of the alignment block as shown and ensure that the correctprobe diameter for the arm is entered.


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The alignment works by capturing the same planes with the probe and thenthe sensor. Once the data is captured the computer calculates atransformation matrix to map the sensor data on to the x, y, z data from thearm.

For each face of the alignment block the same procedure is followed. The firststep is to capture points on the face using the probe on the Faro arm. Pointsshould be taken as shown in the diagram below.

As the points are taken an estimated RMS reflecting the accuracy of theresults is displayed. If this is higher then the expected results then investigate

this prior to continuing.


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The next step involves capturing the same plane with the laser stripe. In orderto achieve the best possible alignment the same method should be followedeach time you set-up. Follow the images below to capture the 9laser stripes.

DO NOT START THIS UNTIL THE SENSOR HAS WARMED UP FOR AT

LEAST 20 MINUTES. A WARNING WILL APPEAR IF THE LASER HASBEEN ACTIVATED FOR AT LEAST 20 MINUTES


1.

2.

3.

4.

5.

6.

Rear View Plan View

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When all of the stripes have been captured an estimated RMS reflecting the

accuracy of the results is displayed. If this is higher then the expected resultsagain investigate this prior to continuing.

The process of capturing the points then the stripes now needs to becompleted for the remaining four planes.

Once all the data has been captured the computer will calculate thealignment.

Before starting to scan the alignment should be checked. There are severaldifferent ways that this can be done.


7.

8.

9.

Rear View Plan View

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Parallel Plane Check

Slowly scan Plane 1 (in the direction of the blue arrow) horizontally in onecontinuous motion, keeping the sensor approximately normal to the surface.

Pause the scan, rotate the sensor 180 degrees and scan plane 1 again.

Now scan Plane 3, in the same manner.

This can either be completed on panes 1 and 3 or 2 and 4.

Delete any points scanned that are not on the surface of either of the planes.Then select one of the planes (use lasso tool).

Select the Points/Fit/Parallel Planes menu item.

Enter the certified distance between the parallel planes and press Apply. Theparallel plane fit results dialog box appears. Check this result against thatexpected for your system.

Plane deviation from the centre - is the error between the certified distancebetween the planes and the measured distance between the planes, but it isshown as the error for one plane only.


Plane 1 Plane 1

Plane 3 Plane 3

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Alignment Verification

Make three passes with the scanner along the edge of the alignment block asshown (red, green, and blue). Then rotate the view and look along the edge. Itshould not be possible to see the separate passes.

One additional test at this stage is to fit a plane to each face of the alignmentblock.


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Set-up Exercise

Each trainee should go through calibrating the probe and aligning the sensor(larger groups may have to split this between pairs).

Set-up Review

Discuss the following points with your course tutor: -

When would you use a different type of probe calibration?

Considerations prior to starting set-up.

What values should you expect to achieve at the different stages of set-up?


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Scanning

Before You Start - Plan Your Scan

What is your objective?Copying, Modification, Visualisation, etc. Consider all stages of theprocess before beginning to scan. What format will the data need to beexported in?

Can the part be scanned?There are two main considerations with respect to determining whether aparticular part can be scanned. They are surface finish and topology...

Can the part be painted?If the surface is too shiny it will produce noise in the data, Matt finish

preferred.

How will the part be scanned?The area to be scanned and the density of data required should also bedetermined at this stage.

Localiser Handling

When setting up the ModelMaker system to perform a scanning job, first

check that the localiser and sensor geometry allows you access all areas ofthe part. To do this, perform a quick dry run with no scanning to ensure:

That you can scan with the sensor at the nearest point of theobject to the arm base without the arm being in a bad orientation.

That you can scan at the furthest point of the object from thearm base. If you are capturing datum points from the part, check thatthe probe has access to these points.

If you are using datum cones, for example scanning a whole car,it is recommended to perform a dry run to ensure the layout is correct

for the size of object.

When positioning an arm, try to avoid:

Collisions between arm and object, this can move the object orthe arm Not being able to reach to scan all parts of the object Arm reaching the end of travel on any of its joints, can adderrors Excess twisting of the sensor and arm cables



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Scanning

Scanning Strategy

Strip scanning is the most efficient Creating a number of strips by scanning in passes

Try to make one pass over each area of the model with only a smalloverlap

Always move the sensor in one direction (probe first), smoothly andconsistently

Always capture sufficient data in areas of high detail/curvature

Sensor Orientation

In general keep the laser directed approximately 90 degrees to the surface.


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Scanning

The ideal approach for most scan jobs is to collect very dense data onfeatures and sparse data in between.

Orient the stripe across a feature line or an edge and follow along the line.

Scanning Tips

RigidityDuring scanning the object and localizer base must not move relative to eachother.

Use a strong bench, tripod or magnetic base

Attach the object to the bench

Laser reflection or absorptionShiny, glass, unpainted plastic or matt black objects do not scan well due tolaser reflection or absorption.

Try and check higher laser power setting 2,3,4

Try lower ambient thresholds.


Stripe is at 900 across astyle line and across anedge

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Scanning

Scanning Preparation

To optimise for different colours the laser power and ambient threshold areadjusted. As a rough guide for light colours a low laser power is used i.e. 1and for dark colours a high laser power is required. When changing the laserpower the ambient threshold should also be adjusted. Use the calibrated viewto help optimise the settings of the sensor.

Laser Power - Click and drag the indicator to the desired setting. (1 is theminimum, 4 the maximum).

Ambient Threshold - Sets the sensitivity of the sensor to surrounding light. Ahigh value is used in a bright environment, a lower value in a darkerenvironment. Please note: Lower values can be better at picking up darkercolours.

Material Drop Down List Box this box enables default settings to be storedand quickly retrieved. Set the laser power and ambient threshold to therequired settings, then by clicking on new material these values are thenstored.


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Scanning

Scanning Parameters


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Scanning

Sampling

It is possible to process the data during scanning. Until the user is confidentwith the scanning system we would recommend that the online 1D and 2Dsampling not be used. These functions can always be applied after the scan

has been performed.

Area (2D) Sampling this produces a regular grid of points over each scanpatch.Linear (1D) Sampling - Defines how many points are obtained along the laserline while scanning.

Rendering mode during scanning - enables the user to select the waycaptured data is displayed while scanning.

Maximum Point Spacing During ScanningThese settings are used to avoid large holes in the resulting scan data. Whenthe distance between captured points is larger than the values set here thescanner will stop capturing data. The operator will then see a void on thescreen and can alter their scanning approach to avoid this.

Scan Menu

PreScan is used to set the size of the object toenable a suitable viewing size. The data acquired in

PreScan is not used in the actual scan of the object

Scan is used to capture data from the sensor.

View enables the workspace view to be alteredthrough use of the arm and hand switched.

Datum opens a new menu specifically for capturinggeometric objects.

Multi Site this is a tool for capturing large objects.

This is not covered in this course. See datumsection for scanning with multiple arm positions.

Rest, This is a safety feature to protect anyrecent scan data from accidental modification. Thearm will automatically select this item when in aresting position.

Data Quality


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Scanning

After scanning an assessment of the data quality should always be made.

Problems with scan date can usually be divided in to one of the followingcategories.

Overlaps / Scarring This is typically caused by a poor alignment.

Perform an alignment check.

If this is poor then perform a probe calibrationcheck.

The next stage would be to do a completesetup of the system.

Ensure that the part and localiser are not moving.

Has the probe worked loose?

Synchronisation due to memory being completelyfull.

Noisy Data My physical object is perfectly smooth, why isntthe data?

The surface finish may not be suitable forscanning and should be prepared prior toscanning.

Even coloured parts can be transparent to thelaser and may require preparation.

All scanning systems are affected by the speckle interference ofmonochromatic light on sub-micron surface imperfections. The result is noisein the resulting scan data. On many surface finishes the size of this noise isvery small and does not affect the data. All scanning software typically hastools to remove this when it is a concern, in ModelMaker this is done using themerge command.


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Scanning

When scanning the file should be saved on a regular basis. It is possible thattoo much data is captured for the computer to handle, in this event a warningmessage will be shown. In the table below an indication is given for the timethat it may take to fill the memory. Online sampling can be used to avoidrunning out of memory; it is not recommended that this be used until the

operator is competent with the scanner.


Scanning time vs PC memory

0

20

40

60

80

100

120

128 256 384 512 640 768 896 1024

RAM Memory (Mb)

ContinuousTim

eScannin

(mins

)

Scanning Time (raw)

Scanning Time (using on-

line 2D sample

1mmx1mm)

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Scanning

Scanning Exercise

Each student must complete this exercise individually.

The object of this exercise is to create a scan of the object mounted on the

board. When scanning considerations should be given to the set-up of thepart and system and also the data acquired.

With the assistance of the course tutor follow this advised approach to scanthe object: -

Position the part relative to the scanner can the complete geometry becaptured?

Optimise the scanner for the surface finish of the part.

Does the part require any preparation?

Consider scanning approach to be used on the part angle of laser line tofeatures, position of sensor relative to the surface.

When scanning try to avoid over scanning the same area several times.

Scanning Review

ModelMaker is a delicate and valuable instrument and should be treatedlike one.

Before commencement of any scanning/alignment procedures the sensorshould switched on and allowed to stabilize for between 20-30 minutes

Do not block the optical path of the laser or CCD sensor to the object.

Make sure you do not touch the optical wind.

Removal of any of the covers/lenses on the ModelMaker system willinvalidate any warranty.

Laser light is emitted from the aperture in the centre of the sensor. Neverlook into the laser aperture.

It is recommended that the laser is left active when the arm is at rest, thisavoids warm up times and can actually help to prolong the life of the laser.

After scanning analyse the data with the course tutor.Consider the following points: -

Data density

Speed of scan

Angle of laser lines

Holes in data?

Reverse scans?


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Datuming

Unlike some optical measuring systems, ModelMaker has the ability tocapture hard datum points from physical objects using the localiser touch

probe. Taking points in this manner can achieve a more accurate result thanusing the scan data. Datum features can also be created from the scan data ifthis is more applicable.

By capturing datum features from an object the scan can be aligned to theCAD co-ordinate system. This can be done prior to data capture so that thescan data is captured straight in to the desired co-ordinate system.

Datum features can be created in three ways:

Interactively via the localiser and Datum pane

Through the Datuming_New entity menu (typically to create referencedatums)

By fitting datum entities through scan data, through the Points_Fit menu.

If you are a CAM2 Measure user, you may prefer to use the functionality ofCAM2 to create co-ordinate systems. These can then be imported in toModelMaker so that the scan data is captured in the same co-ordinate systemas geometric entities created in the Faro software.

Datuming Menu

When entering the datuming menu we can find two different tools:

New entity: this command will allow us to create entities such as points, lines,Using existing entities or entering co-ordinates.

Generate co-ordinate system from: this command will allow us to create anexact copy of the co-ordinate system used in the CAD model using featuresfrom the object.



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Datuming

Datuming New Entity Menu

There are several different ways that datum points can be created fromexisting features, these are typically known as new points.

Creating New Points

Co-ordinates: creates a point byentering the XYZ co-ordinates. Usethe name field if you wish to changethe name

Intersection: Creates a point in theintersection between an existing lineand plane. Use the name field if youwish to change the name.

Average: Creates an average point ofthe selected points. To select thepoints we want to use, we just have tohighlight the point on the left-handwindow and hit the add>> button.The point created will be the average

point of all the points in the right-handwindow.


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Datuming

Projection: creates a point byprojecting an existing entity onto aplane. The entity is projected usingthe planes vector direction and thecreated point will lie in the plane.

Three planes: Creates a point in theintersection point of the existingplane. Use the name field if you wishto change the name

Line: Creates a point using the edges(first point-last point) or middle pointof an existing line. Use the name field

if you wish to change the name.

Sphere: Creates a point using thecenter point of an existing sphere orcircle. Use the name field if you wish

to change the name


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Datuming

Creating New Lines

Co-ordinates: creates a line byentering the co-ordinates of thestarting and ending points. Use thename field if you wish to change the

name

Two points: creates a line betweentwo existing points. Use the namefield to rename the created line. The

results will be shown on the bottompart of the window.

Two planes: creates a line in theintersection of two existing planes.

The length of the line will depend onthe size of the planes. The createdline can also be named on thecorresponding field.

Cylinder: Creates a line using the axis

direction of an existing cylinder. Thelength of the line will be the same asthe cylinders height. The line can berenamed on the name field.


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Datuming

Creating New Planes

Point and normal: creates a plane byusing an existing point and a vector

information. The selected point will beat the center of the plane and will lieon the plane. The results will beshown at the bottom of the window.Use the name field if you wish tochange the name

Three points: creates a best-fit planethrough three existing points. The

positive direction will be calculatedusing the right-hand rule. Use thename field if you wish to change thename

Line and point: Creates a best-fitplane using an existing line and a

point. Use the name field if you wishto change the name

Two lines: Creates a best-fit plane

using two existing lines. This tool onlyworks with coplanar lines (planes withsame direction). The name of thecreated plane can be changed in thename field.


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Datuming

Circle: Creates a plane using theprojection plane of an existing circle.The results will be shown on thebottom of the window.

Creating New Spheres

Co-ordinates: Creates a sphere byentering the co-ordinates of the centerand the desired radius. The name canbe entered in the corresponding field.

Creating New Cylinders

Co-ordinates: Creates a cylinder byentering the base centre point co-ordinate and the top centre point co-ordinate. The diameter of the cylinderwill depend on the value entered in

the radius field.


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Datuming

Creating New Circles

Creates a circle by entering the XYZ

co-ordinates, the radius and thevector information. The name of thecreated circle can be changed in thename field


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Datuming

Interactive Creation of Entities Through the Datum Menu

This command will allow us to measure different entities by using the touchprobe.

To access these menus expand the Datum option in the scan menu.

Measuring Entities:

Point: when selecting this command we will be able to measure an averagepoint. Hit B button to start collecting point and B button again to stop. Hit Abutton to finish measuring.

Please note that the points taken correspond to the center of the probe (non-compensated points).


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PointCaptured


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Datuming

Line: In order to measure a line you will need to take a minimum of threepoints. Take the first point, followed by the middle point and finally the thirdpoint (using B button). Press A button to finish the session. This line will becreated offset from the surface at a distance equal to the radius of the probe.

I.e. probe diameter 6mm, the line will be 3mm away from the surface.

Plane: This entity requires a minimum of three points. Take points anywhereon the plane with B button. Once we have enough points, hit A button. Thesystem will prompt us for another point in order to establish a normal directionand the compensation of the probe radius. To take that point, we need tomove away from the plane and hit B button. A RMS will appear on the screen.Hit B button again to confirm entity.

Sphere: A sphere can be defined with a minimum of four points. Take thepoints as evenly spread as possible by pressing B Button. Hit A button tofinish measuring. Since the sphere is created with non-compensated points,The resulting sphere will be X mm bigger than the original sphere, X being theprobe diameter.

I.e.: probe diameter = 6mm; resulting sphere diameter = 50mm real

sphere diameter = 44mm


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3mm3mm

Original sphere Diameter: 44mm

Probe Diameter: 6mm

Created sphere Diameter: 50mm


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ModelMaker can apply probe compensation after the element has beenmeasured (only spheres and circles can be compensated). To do so, we needto go into the entities pane and highlight the entity we wish to modify. Whenpressing the RMB on top of the highlighted entity, the following window will

appear:

Cylinder: This element requires a minimum of 12 points spread around thecylinder. Press B button to collect the points and A button to finish themeasurement. Press B button again to confirm entity.

Please notice that the radius of probe will not be compensated.

Circle: This entity will require a minimum of three points and a projectionplane. As soon as we select the circle entity, the following window will appear:

You can select an existing plane as the projection plane by selecting it fromthe drop-down menu and press OK. If we havent got the desired projectionplane, we can define it prior to measuring the circle by pressing Capture.

Take the points by pressing B button (notice that we will need to follow themeasure plane instructions if we selected Capture before measuring thecircle). Press A to finish measuring and B button to confirm entity.

When measuring circles, the probe diameter is not compensated (dependingon software version). Please refer to measure sphere in order to compensatethe probe radius if required.


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Selecting Increase Radius willallow us to compensate theradius of the entity. We can entera positive value (for insidemeasurement) or a negativevalue (for outsidemeasurements). We can alsokeep the measured entity byticking the Create Copybox.


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Required Points for New Entity Construction

Entity MinimumNumber Of Points ProbeCompensation Can Entity BeCompensated?

Point Average No No

Line 3 No No

Plane 3 Yes Yes

Sphere 4 No Yes

Cylinder 12 No No

Circle 3 No Yes


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Original Circle Diameter:20mm

Created Circle Diameter:14mm

Probe Diameter:6mm

P1

P2

P3


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New Point Creation Techniques Comparison

CreateEntity

Method 1 Method 2 Method 3 Method 4 Method 5 Method 6 Method 7

PointCo-

Ordinate(X,Y,Z)

Intersection

Plane-Line

Average

Projection

Point-Plane

Sphere/Circle

(Centre)

LINE(First,

Middle,

Last)

3 Plane

LineCo-

Ordinate(X,Y,Z)

2 Points2 PlanesIntersecti

on

CylinderAxis

- - -

PlanePoint And

Normal3 Points(Best-Fit)

Line AndPoint

(Best-Fit)

2 Lines(Coplana

r)

Circle(Projectio

n

Plane)

- -

Sphere

Co-Ordinate

AndRadius(X,Y,Z)

- - - - - -

Cylinder

Co-Ordinate(2 Points)

AndRadius

- - - - - -

Circle

Co-

Ordinate,Radius

AndNormal

- - - - - -


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Co-Ordinate System Generation Methods

3-2-1 Alignment:

PLANE: Select the plane that defines the direction of the axis selected in theCo-ordinate frame.

COORDINATE FRAME: Is the direction that the selected plane is going todefine.

0XY: defines Z-axis direction (vector direction = positivedirection).

0YZ: defines X-axis direction (vector direction = positivedirection).

0XZ: defines Z-axis direction (vector direction = positivedirection).

LINE: the selected line will be projected onto the previous plane and willdefine one of the two remaining axis directions. That line can be selected intwo ways:

From list: select an existing line (measured or created)

Plane intersection: it will create an intersection between the plane selectedpreviously and the plane selected in this field.

AXIS: In this field we have to select what axis and sense (positive or negative)is the line defining.

Please notice that the options in this field will depend on what axis the firstplane is defining.

ORIGIN: the point selected in this field will become the origin (x=0, y=0,z=0)of the co-ordinate system. We can also define that point in two ways:


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From list: select an existing point (or point reducible entity such as Sphere,circle,)

Plane intersection: it will intersect the plane selected in this field with the lineselected in the previous step, or with the two previously selected planes

(planes in the previous fields).

Three planes:

0XY: the plane (its vector information) selected in this field will define the Zaxis direction.

0YZ: the plane (its vector information) selected in this field will define the Xaxis direction.

0XZ: The plane (its vector information) selected in this field will define the Yaxis direction.

Notice that all three planes should be orthogonal. If the planes are notorthogonal, the co-ordinate system will be created as follows:

The plane entered in the first field will defined the Z axis direction (as itnormally would). The intersection of that plane with the plane entered in thesecond field will define the X axis direction. Finally, The intersection of thethree entered planes will set the origin.

N Points:


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This alignment requires a set of points in theCAD co-ordinate system, and a set ofcorresponding points in the global co-ordinatesystem (not- aligned points). We need tomatch the GLOBAL point (first field) with thecorresponding CAD point (second field). HitAdd to accept the pair of points. If we make amistake, highlight the wrong pair and hitremove. Repeat this operation for all thepoints. Once we have all the points matched,hit OK and a transformation RMS will beshown on the bottom of the window. It willrequire a minimum of three pairs to carry thisalignment on. If we make a mistake, highlight

the wrong pair and hit remove.See the exercise at the end of this chapter fora worked example.


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Single plane:

Using this alignment we will only be able to set one of the axis direction. Wewill not be able to define the direction of the two remaining axes or the originof the co-ordinate system. In the name field we enter the name we want theco-ordinate system to have. In the Plane field we enter the plane which isgoing to define our axis. Finally, we use the Co-ordinate field to establish whataxis is the plane defining.

Required Entities for Different Alignment Techniques

Alignment Required Entities Method

3-2-1 Alignment

-3 Planes-2 Planes And A Point-2 Planes And A Line-1 Plane, 1line And A

Point

-The Vector Of Plane 1Defines X, Y Or Z

-A Line Defines One OfThe 2 Remaining Axes.

-A Point Defines TheOrigin.

Three Plane - 3 Planes

-Plane 1 Defines X,Y OrZ

-Plane1/Pane2Intersection. Line

Defines A Second Axis.-Intersection Of ThreePlanes Defines The

Origin.

N-Points - Point Reducible Entity

- Match Measured/Created Points With

Corresponding CadPoints.

Single Plane - 1 Plane

-The Plane DefinesEither X, Y Or Z-Axis.

The Remaining 2 AxesAnd Origin Cannot Be

Defined.

Viewport - None

-Aligns The Viewport ToThe 0XY Plane (Z-Axis).

The Two RemainingAxes And The Origin

Cannot Be Defined.


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Alignment Viewports

This alignment is particular case of single plane alignment. This option alignsthe current view plane to the 0XY plane. Before using this alignment, we needto get the view plane we want to use as 0XY (notice that any of the standard

viewports can be used). The transformation will occur as soon as we hit theviewport alignment option.

Transformation and Rotation of ANY Alignment

Sometimes we cannot get the desired alignment just by using any of theprevious alignment methods. This can often be achieved by using analignment then transforming the alignment.

If we tick the translate and/or rotate box, we will activate the

translation/rotation parameters.

Using the translation parameters will allow us to move the origin to a specifieddistance from the current origin. We can move all three axes or move onlyone.

Using the rotation parameters will allow us to rotate each axis to a newposition using angular values. We can rotate all the axes at the same time orindependently.

We can use translate and rotate independently or combine both of them inorder to get the desired alignment.

Finally, we can create a copy of the actual alignment by ticking the Createcopybox. This can be helpful if we dont get the desired alignment and needto go back to the original alignment.

*NOTE: You will find the transform/rotate window in the entities pane (left-bottom side of the screen). All you need to do is to put the mouse cursor ontop of the desired system (alignment) and click the RMB. The window willappear when you select transform from the following drop-down menu:


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Import/Export Alignment files (CAM2 Measure users only)

If you are a CAM2 Measure user, you might want to Import/Export analignment created in CAM2 Measure. All you need to do is export the .pos filefrom CAM2 Measure, and then import it into ModelMaker by usingFile/import and selecting the .pos type of file. The alignment should beautomatically activated, however, 3DScanners highly recommends to checkthe origin and directions of the axes to make sure we imported the desired co-

ordinate system.

We can check at any time what alignments we have got (if any) and whetherthey are activated or not. To do so, all you need to do is go into the Entitiespane and click on top ofDatumingwith LMB. We will see a list of all the datumand co-ordinate systems we have. Use the RMB drop down menu to apply(activate alignment) orapply reverse (de-activate alignment).


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Datuming Exercise N Point Alignment.

Exercise objectives Understand how two separate scans can be combined together.

Be familiar with the N-point alignment tool.

This is a typical example of aligning two separate scans into the same co-ordinate system using N-points alignment method; this method is alsocommonly referred to as leap frog.

Due to the shape of the object it is not possible to obtain complete coveragefrom one arm position without moving the part. The object has been scannedin two separate processes using three spheres as the common items betweenboth scans.

The complete scan.


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The approach to this exercise is shown in the flow diagram.

There are several key points with the approach to this exercise.

Notice how the spheres are spaced as far apart from each other aspossible. This ensures that the best possible result is obtained.

In a real exercise it is recommended that at least five points be used. Thishelps to average the error and in the event that any spheres are notusable this should still hopefully leave three or four usable spheres.

The minimum number of scans has been taken to achieve the objective ofa complete scan for the part never take more scans than necessary.


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Scan side A including reference

spheres, save and close file

Open both files in separatewindows in ModelMaker

Create reference spheres in both files

Copy and paste reference files fromfixed scan to mobile scan

Use N point alignment to create newco-ordinate system, copy and paste

scans together and combine

Scan side B including referencespheres, save and close file


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Work through the following instructions to complete this exercise.

Load datasets (BoneA.sab and BoneB.sab) into ModelMaker. These shouldbe in separate windows.

Datum Entity Extraction

Working in file BoneA.sab.Use the lasso tool to select each sphere individually and fit a sphere to allthree.For each created entity rename it to " New Sphere X", where the X is number1, 2, 3. This is done in the entity pane.

Tip

Make use of the tile command under the windows menu to make it easier toview both files at the same time.

Repeat the above for file BoneB.sabWhen renaming the spheres the names should reflect the naming conventionin the first file.

Both files should be similar to the example below.

Tip.Spheres are difficult to scan, especially smaller ones! Make use of the errormap tools to check for rogue data. When rogue data is found delete this andfit a new sphere.


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Copying of Data into a Common Viewport

Select all of the created spheres in the file BoneB.sab by right clicking on thedatuming folder of entities pane

Once selected these can then be copied and then pasted in to the fileBoneA.sab

File BoneA.sab should now resemble the images below.


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Matching of Alignment Entities

From Datuming/Generate Co-ordinate System menu option select Alignmentfrom N Points

Using drop down menus and "Add button, select the corresponding points.

The n points alignment has created a new co-ordinate system that exists in

the entities pane. When this is first created it is not applied; the user mustmanually apply the co-ordinate system.


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Application of the Transformation Matrix

Apply new co-ordinate frame to the scene. Right click on the co-ordinateframe in entities pane and select - apply.

All of the data in BoneA.sab has now been moved so that it is aligned to thesecond scan BoneB.sab.


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Copy all the points from the first dataset BoneA.sab

Paste the points from BoneA.sab to the BoneB.sab

This should now look like the following image.

The two scans can now be combined in to one entity.

Datuming Review

Discuss these points with the course tutor

Alternative types of reference points that can be used.

Number of reference points that have been used.

Mounting methods of spheres.

Which data set has been moved?

How could this technique be expanded for larger objects with morepositions?


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3d laser scanning with modelmaker

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