Geography 121Geography 121Project 3 PresentationProject 3 Presentation

National Map DataNational Map Data

by Ron, Lauren, and Hannahby Ron, Lauren, and Hannah

Objective for Project 3Objective for Project 3

Ability to find, download, and view

National Map Data of your

hometown or area of interest.

IntroductionIntroduction

• This project will be evaluating the use of aerial photography and elevation data in the creation of maps.

• Many developed countries’ government programs have developed large sets of topographic maps to help build roads and cities.

• The U.S. Geological Survey (USGS) is responsible for topographic mapping in the U.S..

• We have already learned in class, that a vertical aerial photograph is an image taken from above the Earth's surface.

• Elevation data on the other hand is used to calculate slope. (Previous lectures) Raster elevation data tends to be best.

Three types of National Map DataThree types of National Map Data

• (DEM) Digital Elevation Model

• (DLG) Digital Line Graphs

• (DOQQ) Digital Orthophoto Quarter Quadrangle

How to get started!!How to get started!!

First few steps:

• Go to my computer

• Find your WWW drive

• Make a folder, “Map Data” for the project

• Make 3 separate folders for each type of map; called DEM, DLG and DOQQ

• You need these to hold the downloaded data for each map

What are DEM’s?What are DEM’s?

• Digital maps showing land elevation of Earth areas

• Most maps made through use of aerial photographs

• Used the most due to simplicity• Good for showing land features• A DEM is a raster illustration of a terrain surface.

Raster: FROM OCT. 18 LECTURE - Data broken down into grid cells

- One cell has one attribute, groups of cells form objects

What a DEM looks likeWhat a DEM looks like

Uses of a DEMUses of a DEM

• Depicts the Earth’s elevation of a place of interest or in this case, your hometown

• Shows physical features of a chosen place or position:

Rivers, lakes, mountains, etc.

Creating your own DEM Creating your own DEM

• Enter the website: http://seamless.usgs.gov• On the right you will see,“View and Download United

States data.” Click on it!• Take your mouse and draw a square around the chosen

area• NED Relief (1 arc second) must be checked under the

elevation tab• Use the “define downloads area” on the left hand side.

YOU MUST CLICK ON IT!• Target the area, and then click download

Creating continued….Creating continued….

• Hold your horses! The download takes some time• Open the file. Click “use evaluation version”• Highlight all the files and click “extract”• Extract the files to the DEM folder you made previously,

then OK• Find and open the ArcMap program• Go to Add Data and find the map you are using• The computer might ask something about pyramids, just

click Yes to all pop-ups, the map should appear• Save this file to your WWW!

Uploading DEM imageUploading DEM image

• When your map is uploaded, hold down alt and print screen so you will take a screen shot of the program to put on your website

• Now go to Start, Accessories, and then Paint• Go to Edit and click on Paste, your image should

appear• Save this image in your WWW folder.• You can now use this image for your project. • REPEAT THESE STEPS FOR ALL 3 MAPS!!

Further DEM help Further DEM help Sources Sources

• http://rmmcweb.cr.usgs.gov/elevation/dpi_dem.html

• http://www.personal.psu.edu/mhp124/121%20Home.html - UNDER PROJECT 3

• http://edc.usgs.gov/products/elevation/dem.html

DLG ScalesDLG Scales

• Digital vector representations of cartographic information

• Made of nodes or points, line segments connect to these nodes, and these areas are formed by 3 or more line segments

DLG Scales continuedDLG Scales continued

• Large Scale (7.5 minutes): 1:20,000, 1:24,000, and 1:25,000.

• Intermediate Scale (60 minutes): 1:100,000

• Small Scale: 1:2,000,000 and are split by State or split into sections

What DLG Scales ShowWhat DLG Scales Show

Boundaries- (ex: Political)

Hydrography- (ex: Lakes, Rivers, Streams)

Hypsography- (ex: Contour lines, 50 Meter Contour Interval)

Public Lands- (ex: Section Lines)

Transportation- (ex: Miscellaneous Features, Roads, Railroads)

How to create a DLGHow to create a DLG

• 1st: http://arcdata.esri.com/data/tiger2000/tiger_download.cfm

• 2nd: Chose your state• 3rd Chose your County & 3 or more Variables

(Physical, Rails, Roads, Landmarks etc..)• After Choosing Select “Download File”

– (Use Evaluation Version)

(Continued Next Page)

DLG Cont.DLG Cont.

• 4th: Create New Folder

• 5th: Highlight all files and Extract them into New Folder

• 6th: Open Arc Map

• 7th: Select “Add Data”

• 8th: Go to New Folder and Highlight all Data

DLG ImageDLG Image

Another example of DLG imageAnother example of DLG image

DLG Helpful SourcesDLG Helpful Sources

• http://eros.usgs.gov/guides/dlg.html

• http://www.epa.gov/nsdi/projects/dlgstate_pol.htm

• http://www.fws.gov/stand/standards/dl_hypso_rev1.html

What is a DOQQ?What is a DOQQ?

• Computer Generated Image• Aerial Photograph• Image Displacement Caused By Terrain

Relief And Camera Tilts Is Removed • Possible to Measure Directly On It• Created by scanning aerial photograph

transparency and digitally rectifying the image to an orthographic projection (orthorectification)

Uses of DOQQUses of DOQQ

• They are mostly used in editing vector planimetric data. – Road data can be taken by the state and

plotted over DOQQs so that they can then be changed to show the new road layout.

This was found in the Online Text, Module 3, Part 2

DOQQ ImageDOQQ Image

Creating A DOQQCreating A DOQQ

1.1. Use http://seamless.usgs.gov Use http://seamless.usgs.gov

2.2. Like the DEM, zoom into your area Like the DEM, zoom into your area

3.3. In the Orthoimagery tab, select In the Orthoimagery tab, select “DOQQ Color Mosaicked Image.”

4. Using the Define Download Area button highlight the area you want to download

1. Make the area small

Continued Creating a DOQQContinued Creating a DOQQ

5. Proceed with the same download, extract and loading into ArcMap as the previous two maps

1.1. Warning: DOQQ Files are huge! Warning: DOQQ Files are huge!

2.2. Delete them after you use them!Delete them after you use them!

Finally….lets wrap things up!Finally….lets wrap things up!

• DEM: Relating back to previously learned material

-In Module 4, Part 3; “DEM's are cast on theTransverse Mercator projection used in thelocal UTM zone.” The USGS 7.5-minutetopographic quadrangle set is the mostdetailed data. DON’T FORGET: No map is completely accurate,including DEM's!

DLG ConclusionDLG Conclusion

• DLG Provides Useful Data– Many Perspectives– Good for evaluating an area– Planning– Finding Problems and Solutions

DOQQ ConclusionDOQQ Conclusion

• Due to the scale of the map, 90% of well-defined points are 20 feet of their actual positions.

• However, error arises during the rectification process, when the image is warped in order to have 16 points match their actual location

• The main part of the DOQQ is the pixels. Each pixel represents a number, 0 for black, 255 for white, and levels of gray in between.

• This information was taken from the Online Text, Module 3, Section 2

Project Page DirectionsProject Page Directions

• Refer to http://www.geog.psu.edu/courses/geog121/projects/proj3_example.html

SOURCESSOURCES

• For DEM and DOQQ Maps- http://seamless.usgs.gov• For DLG-

http://arcdata.esri.com/data/tiger2000/tiger_download.cfm

• Definitions and uses of maps: http://esri.com/• Understanding Geographic Data Online Text:

http://training.esri.com/Courses/geodata_ArcGIS/index.cfm?c=31&CFID=133657&CFTOKEN=26539680&jsessionid=a23063e377ce3f4512d7

• Helpful website: http://www.personal.psu.edu/cjg5024/

Need our help? Just ask..Need our help? Just ask..

• Lauren Rosenman: e-mail – ljr5000@psu.edu

• Hannah Ryan: e-mail – hnr104@psu.edu

• Ron Feingold: e-mail – rsf148@psu.edu