Using Digital Elevation Model (DEM) Data
in ArcView 3, ArcView 8, & ArcView 9

A. Downloading the data
B. Preparing the data with AV3
C. Preparing the data with AV8.x
D. Preparing the data with AV9.0


A. Downloading the data

You can download DEM ("digital elevation model") data for any place in the US from the GIS Data Depot. It looks complicated but it's very easy, and the data are very cool to play with!

  1. Go to www.gisdatadepot.com. (You will need to log in before you can download data, so you may need to create a free profile.)
  2. In the center, choose the "Download GIS Data" button.
  3. In the US map, click on your state, e.g. California.
  4. Choose your county, e.g. Fresno
  5. Click the choice for "Digital Elevation Models (DEM) - 24 k".
    (Jump to here.)
  6. Find your desired quadrangle/s. (You can locate quadrangle names on the TopoZone website.)
  7. Click the green "download" arrow (green is free).
  8. On the page that appears, right-click and save both the linked files that are visible. Files that end in ".DEM.SDTS.TAR.GZ" are the actual DEM files, and the "DEM.SDTS.TXT" files tell you important info about the DEM files. Download all these files, being careful to note where you save them, such as
    "c:\gisdata\download".
  9. For this example, I will use the file "1662537.DEM.SDTS.TAR.GZ" from the "Fresno North" quadrangle. Make sure you have WinZIP or some such uncompression utility installed and available.
  10. In Windows Explorer, navigate to the downloaded files. The number is simply a filename used by USGS in their data prep. "SDTS" stands for "Spatial Data Transfer Standard", which is a way of storing the data. "TAR" tells you this is a "tape archive" file which is for Unix users, and "GZ" tells you it has been zipped using something like GnuZip for Unix. Basically, all you need to know is that it is a "doubly-compressed" file. When you double-click it, WinZip has to create a temporary folder for it, so let it do this, and then it will ask to unzip a series of files, all beginning with a 4-digit number, such as "8907". These are the SDTS files that the USGS uses to distribute the data in a "non-proprietary format".
  11. Extract ALL these files into a folder, such as
    "c:\gisdata\download\sdts".
    This is a fast process, as the files are small. Then exit WinZip.

B. Preparing the data with AV3 ... see Steps 12-16
C. Preparing the data with AV8.x ... see Steps 17-25
D. Preparing the data with AV9.0 ... see Steps 26-35


B. Preparing the data with AV3

  1. In Windows' "Start" menu, go to the ArcView 3 program group and engage "SDTS Raster to Grid". (You'll only find this if your computer has Spatial Analyst or 3D Analyst installed.)
  2. In the top line of the utility, put the path and 4-digit number of the SDTS files, such as
    "c:\gisdata\download\sdts\8907".
    In the bottom line of the utility, put the path for where you want it saved. This should be a folder, such as
    "c:\gisdata\download\grid1"
    Click OK.
  3. A black DOS window will appear and a process will run, then the window will quickly exit.
  4. Look in the folder "c:\gisdata\download" and you will see a new folder "grid1" as well as an "info" folder. If you create "grid2" and "grid3" in the same "download" folder, all three of these grids will rely on the single "info" folder.
  5. You can now work with your data inside ArcView Spatial Analyst or 3D Analyst. If you want to integrate decimal degree shapefiles with this, you need to know what coordinate system the grid was stored in, so go back to your original "1662537.DEM.SDTS.TXT", which is just a text file, and double-click it. It should tell you the coordinate system (or projection, such as "Transverse Mercator"), the zone (such as "11"), and the datum (such as "1927"), so this is a "UTM 1927 Zone 11" data set. In ArcView, set the View/Properties/Projection to the coordinate system which matches the information found in the text file.


C. Preparing the data with AV8.x

  1. In Windows' "Start" menu, go to the ArcGIS program group and engage "ArcToolbox".
  2. Look in the "Conversion Tools", and choose "Import to Raster", then double-click the "SDTS Raster to Grid" tool.
  3. In the top line of the utility, use the browse tool to navigate to the folder and select the 4-digit number of the SDTS files. This puts the information in the top line, such as
    "c:\gisdata\download\sdts\8907".
  4. In the middle line of the utility, choose "1-ELEVATION"
  5. In the bottom line of the utility, put the path for where you want it saved. This should be a folder, such as
    "c:\gisdata\download\grid1"
  6. Click OK. The process will run, then the window will quickly exit.
  7. Look in the folder "c:\gisdata\download" and you will see a new folder "grid1" as well as an "info" folder. If you create "grid2" and "grid3" in the same "download" folder, all three of these grids will rely on the single "info" folder.
  8. You can now work with your data inside ArcView 8 with Spatial Analyst or inside ArcScene. If you want to integrate other data with this, the other data simply needs to have proper projection information stored with it.
  9. If you need to know what coordinate system the grid was stored in, you can go back to your original "1662537.DEM.SDTS.TXT", which is just a text file, and double-click it. It should tell you the coordinate system (or projection, such as "Transverse Mercator"), the zone (such as "11"), and the datum (such as "1927"), so this is a "UTM 1927 Zone 11" data set. Alternatively, you can use ArcCatalog to explore the spatial information of the data.


D. Preparing the data with AV9.0

  1. In Windows' "Start" menu, go to the ArcGIS program group and engage "ArcCatalog".
  2. Right-click in the grey space of the menu bar and turn on the "ArcView 8x Tools" toolbar. Position the toolbar where convenient.
  3. Click the "Conversions" drop item and choose "SDTS Raster to Grid"
  4. In the top line of the utility, use the browse tool to navigate to the folder and select the 4-digit number of the SDTS files. This puts the information in the top line, such as
    "c:\gisdata\download\sdts\8907".
  5. In the middle line of the utility, choose "1-ELEVATION"
  6. In the bottom line of the utility, put the path for where you want it saved. This should be a folder, such as
    "c:\gisdata\download\grid1"
  7. Click OK. The process will run, then the window will quickly exit.
  8. Look in the folder "c:\gisdata\download" and you will see a new folder "grid1" as well as an "info" folder. If you create "grid2" and "grid3" in the same "download" folder, all three of these grids will rely on the single "info" folder.
  9. You can now work with your data inside ArcView 9 with Spatial Analyst or inside ArcScene or ArcGlobe. If you want to integrate other data with this, the other data simply needs to have proper projection information stored with it.
  10. If you need to know what coordinate system the grid was stored in, you can go back to your original "1662537.DEM.SDTS.TXT", which is just a text file, and double-click it. It should tell you the coordinate system (or projection, such as "Transverse Mercator"), the zone (such as "11"), and the datum (such as "1927"), so this is a "UTM 1927 Zone 11" data set. Alternatively, you can use ArcCatalog to explore the spatial information of the data.



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