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Downloading DEM / SRTM terrain data

The National Map viewer website has recently changed the way that you download the DEM/SRTM files which we use to generate real world terrain for Train Simulator routes. The tutorial below covers how to choose the DEM type, confirm availability for your area, and then download these files. After downloading, you can use the excellent tutorials by bnsfsubdivision to prepare, and import the files into Train Simulator.

The URL for the updated mapviewer is: https://viewer.nationalmap.gov/basic/

1) Click on the checkbox for 'Elevation Products'

Zoom in (real dimensions: 1561 x 973)USGS 1.jpg
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2) Ensure the button for 'Box/Point' is checked, then click a point on the map and drag your cursor to create a green rectangle that covers the entire route that you want to make. In this example I have positioned the rectangle to cover the BNSF rail line from Tacoma to Yakima. You want to make the rectangle slightly larger than the furthest points on the route you are making.

You can adjust the size and position of the rectangle after it is placed also by dragging the white squares on the corners of the rectangle.

Zoom in (real dimensions: 922 x 700)USGS 2.jpg
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3) Check the availability for the type/quality of DEM files you wish to use in your route.

- 1 arc-second gridfloat is the highest resolution/quality DEM that you can import to Train Simulator without using the program ReDem. This is what I recommend for beginner and novice route builders, or those just looking to quickly make realistic terrain for their route.

- 1/3 arc-second and 1/9 arc-second IMG or gridfloat types can be imported if you use ReDem. This is a more complicated process, but gives you terrain this is more accurate in areas with sharp elevation changes. (eg: roadbed cut onto a rocky shelf, or in deep cuttings, etc) Note that 1/9 arc-second data is scarce in many areas.

In the picture below, notice that the background colour of the map has changed, and completely covers the area we have selected for our route.

Zoom in (real dimensions: 1199 x 729)USGS 3.jpg
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In the picture below, I have selected the higher accuracy, but rarer 1/9 arc/second DEM. Notice that the coverage area is limited in the area we have selected for our route. This would not be enough to generate the terrain we will need in just this DEM type.

Zoom in (real dimensions: 1188 x 761)USGS 3.5.jpg
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4) After selecting your DEM type, drawing the rectangle around your route, and checking DEM availability, you can now click 'Find Products'.

Zoom in (real dimensions: 821 x 587)USGS 4.jpg
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5) This is the list of each DEM file you will need to generate the terrain for the area you selected.

Click 'download' on each file. If you have a larger route, you will likely have to scroll down to see all of the files.

Zoom in (real dimensions: 886 x 780)USGS 5.jpg
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Once you have your files downloaded, use 7zip, Winzip, or Winrar to extract each folder.

The above steps replace pages 2-6 of bnsfsubdivision's excellent DEM terrain tutorial. You can follow through the rest of the process with that tutorial, available here: https://www.dropbox.com/s/t55mnj18alimvlh/Searchlight%20Simulations_Terrain_Import_01_05_17.rar?dl=0
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