Depiction 101: Elevation Data Outline

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This session will cover:

  • What is elevation data?
  • What elevation data is available in Depiction 1.3.2 (we've added some new stuff)
  • What you can do with that elevation data
  • Why and how to get higher resolution elevation data

"Elevation data" is a friendly term for a digital elevation model (DEM). One source to read for more information on this type of data is the GIS 101 section of the Depiction User Manual (1.3.1 or 1.3.2). Further technical reading is available on this GIS Wiki page. This model is created by surveying the height of the earth above sea level on a grid. The data is often referred to by the distance between measurement points on the grid (in meters: 90m, 30m, 10m; or arc seconds: 3, 1, 1/3). The smaller the grid, the more data there is and the more realistic picture of the earth's surface it provides.

NOTE: One important thing to keep in mind is that the data only takes the earth's surface into account (in most cases), not any buildings or other man-made structures. Digital structure models (with buildings and such included) are available, but I have yet to find any for free.

Depiction provides 30m data via our quickstart data menu for the mainland US. With version 1.3.2.11589, we added a new set of 90 meter data in the quickstart list internationally. For a list of what countries are covered, see this blog post: http://dpct.it/pMbLbm

When the data is processed into your depiction, you see an image (based on the data) of the topography for the area you've selected. Depiction puts it in a Revealer so it isn't in your way. You will also see "Elevation:" with the height where your mouse is shown in the lower left corner of your depiction screen.

Now you can use some simulation elements (also covered in the simulation elements session): Antenna, Line of sight, Flood, Runoff, Water barrier and Change elevation height.

    To get higher resolution data for your current depiction area (in the USA):
  • If it's available, download Elevation data from Quickstart for your area
  • Start a text file or document you can paste into and copy from easily: type 4 lines
    • Top Lat,
    • Left long,
    • Right Long and
    • Bottom Lat
  • In Depiction, set your view so that you can see and click on all 4 sides of the depiction area
  • Check that your Lat, Long reading in the bottom right is in decimal format (if not, click Tools, then Settings and click on Coordinate format and select the top option [40.44620, -79.94886], click OK)
  • Put the mouse on the top left corner of the golden dashed area boundary, right click, then click "Copy location to clipboard"
  • Go to the document and paste (Ctrl+V) next to Top lat. Select the Longitude portion (the second number) and cut it. Paste it next to Left long
  • Back in Depiction, put the cursor on the bottom right corner, right click and select Copy location to clipboard
  • Go to the document and paste next to Right long. Select and cut the first value and paste it next to Bottom lat.
  • Go to http://dpct.it/qYOAYG (NED 1 arc second and 1/3 arc second Download tool on the USGS site)
    Be sure the input format is set to Area and values in degrees
  • Copy and paste the values from your document into the fields on the page
  • Click submit
  • If 1/3 are second data is available, select the "Pre-packaged ArcGrid format" download
  • When the file is downloaded, open it.
  • Double-click into the first folder, then the "grdn..." inside that. Select all the files in there, and right click to unzip them (this is a function available in Windows since XP) to a folder you can find later
  • Go to your folder and drag the .adf file into your depiction (you may need to put your mouse cursor over the menu bar for this to work)
  • The Add content menu will open with the file selected for import. Click Elevation data as the element type and click Add
  • It may take quite some time for the data to process. When it finishes, you will notice a change in your elevation data revealer (though the name will not change)
    • Note that the new data is merged with the old, so there is only one Elevation data element

If you'd like information about using Canada's GeoBase site, let me know.

Updated by George on 9/30/11
View/download this page as a PDF
Go to the elevation session page or the Depiction 101 page.

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