DEM Data and you: How to use the USGS Seamless Server to make terrains for you

The United States Geographical Survey has fairly detailed terrain imagery for most of the United States. Almost all the contiguous US is mapped in 1/3 arc-second (10m) resolution, and parts are in 1/9 arc-second (3m) resolution.

So how does this help us? Well, using the USGS Seamless Sever you can download elevation data that you can use to recreate real-life locations in Rigs of Rods.

What with the new terrain system coming soon (you can use it already if you compile the program from source), I figured this would be good information for the community to have.

NOTE: There is limited data available for locations outside of the United States. Most of that will be only Shuttle Radar Topography Mission (STRM) data which has very low resolution. (something like 90 meters)

Step 1: Getting Necessary Programs

The programs you will need:

1. MICRODEM: A program for extracting usable heightmaps from DEM data, and other goodies as well. It's kinda oldschool, but it works.

1. An image editing program of your choice. (NOT MSPAINT)

1. A terrain editing program of your choice. Any of the programs listed in the wiki ought to work already, but I prefer L3DT.

Got all that installed? Good, we can continue then.

Step 2: Getting to know the USGS Seamless Sever

Log on to the USGS Seamless Server.

Woah, what's all this then?

(picture 1 here)

All your important tools are on the left there. They have tooltips that will show up when you hover over them.

On the right-hand side are the interesting bits.

• Places: Overlays for place names. Useful if you get lost.
• Layer Extent: Exactly what it says on the tin: these overlays show the extent of other overlays.
• Transportation: Lets you display the location of roads, railways, and scenic rivers. (oooh aaah)
• Boundaries: Shows state boundaries, county boundaries, congressional districts, historic Indian lands, built-up areas... generally these overlays are not terribly useful for our purposes.
• Hydrography: Water imagery. Shows where there's water. (also the surf temperature and where dams are and the levels of arsenic in the groundwater.) This is good for when you're modeling somewhere where the water level isn't sea level.
• Orthoimagry: Essentially satellite imagery. You can use it to get a bearing for what you're looking at, but I generally just keep Google Earth open while I look for data because it's faster.
• Land Cover: Now this is a part we can really use. These overlays show what is on the land that you are looking at. The appropriate keys for them are located in the help section of the websites. These files can almost directly translate into alpha-splat maps. (oooh aaah)
• Elevation: Elevation maps. (duh) Some rough approximations:
  • 1 arc-second: ~30 meter resolution.
  • 1/3 arc-second: ~10 meter resolution.
  • 1/9 arc-second: ~3 meter resolution.

These are all wonderful overlays. But how do you check them out?

Step 3: Data Check-out

So, find the geographic location you wish to check out. In my case it's the old Lackawanna Cut-Off in northern New Jersey.

Use the box tool to make a selection of the area you want to check out. Give it a wide margin on each side; you'll end up trimming the checked out area significantly, most likely.

(image 2)

Now you'll get this popup.

(image 3)

Click "Modify Data Request".

Now you're presented with a myriad of options. Check any data overlays that you want. (MICRODEM can read most of them.)

When you go to select your DEM type, try selecting both 1/3 arc second and 1/9 arc second. You'll probably only get 1/3, but you can try. Change the data type from ArcGRID to GeoTIFF. MICRODEM can't open ArcGRID files as far as I have seen. (image 4) I recommend a few downloads... Orthoimagry, for instance, is great for making terrain overlays. However, it is also very very big in filesize. Railroads and roads overlays can be helpful for placing such objects correctly. Land cover data files are great as starting points for alpha splat maps.

Once you're finished with your selections, hit "save changes and return to summary."

(image 5)

Woah, that's a bunch of data! If your data checkout exceeds 1.5 GB, then you can't download everything at once. Go deselect some things, or reduce the size of your checkout area. Generally orthoimagry is the bulk of the problem, and you can usually just generate those textures later anyway, so it can be safely left out.

Download all the things you need and give the zips proper names. Put them somewhere and unzip them. Now you have a bunch of files which MICRODEM can import.

(under construction, stay tuned for updates...)