For those who are curious, a digital elevation map, or DEM is a 2.5D, color coded representation of land surface. In its original form, a DEM is a swath of return values gleaned from remote sensing (commonly using radar) flown on aircraft, satellites, or on the late space shuttles (the SRTM mission). Lowest height values are returned as dark, highest values as white after processing. Data exist for the entire globe and are completely free. Better resolution DEM are always becoming available. What better resource is there for creating your own virtual piece of the world? All the work of creating valleys and mountains has already been done for you by mother nature over the course of 4bya. All you need to do is a bit of preparation work for importing DEM data into the GECK.
For the purposes of this tutorial I am assuming that you have knowledge of how to import images into the heightmap editor; the GECK is completely unforgiving which is why it may seem unstable for some. Until you become familiar with the general process of importing images into the GECK it will be frustrating. I guarantee it.
With that said, everything you need to know about how to import images into the GECK is outlined here. Images must be named correctly.
The Gist of it:
What I describe in this tutorial is a workflow for converting a DEM to a suitable heightmap. Here are some results using this method in-game, with absolutely NO editing within the GECK.* The DEM that was used covers area around Reno, NV.
*Terrain meshes were generated in order for the heightmap to be visible from a distance. That is all.
Tools you will need:
- VTP (Virtual Terrain Project) available here: http://vterrain.org/Download/ (or similar software capable of reading elevation data. VTP is free.
- Photoshop. Now FREE to download! (Link) Huzzah
The Tutorial, proper:
- 1) Go to the USGS website and locate their NED 1 arc second download tool (LINK);
- Select the state and county in which you are interested.
- 1/3 arc sec offers greater resolution than 1 arc sec. 1/9 arc sec offers even greater resolution (if it is available). Bear in mind the size of the worldspace you would like to edit and figure out how much coverage and resolution you should really need. The size of the Mojave wasteland, while covering Vegas to the North and all the way South to Nipton in California obviously does not represent real-world, to-scale terrain. Liberties can and should be taken for practical purposes.
- Absolutely always download the 'arcgrid' format.
- 2) Import the DEM data from the package you should have downloaded from the USGS into VTP. Go to "Layer" on the menu bar, then "import data," then "Elevation."
- Inspect the DEM. On the menu bar, pull down the "Elevation" tab and select "Fill in unknown areas." This should correct no-return values. Even if the DEM looks fine, it's a good idea, and you shouldn't have to look at a histogram to see if some data are outliers in order to correct them.
- Export you DEM as a BMP. Go to "Elevation," "Export data," then select BMP.
- 3) In Photoshop, open up your BMP image (it could be very large depending on what resolution DEM you have, like >100mb!) You should also note that the image has flipped vertically.
- Select your region of interest, bearing in mind that quads within the GECK (named according to this map) are 1024x1024 pixels across at 72 pixel resolution.
- Go to "Image," "Mode" then select 16-bit. If your image is not grayscale, make it so (go to "Image" then "mode" and select grayscale. Select yes to discard color information.) This is an important step. The GECK reads RAW, 16-bit data. The DEM you have just downloaded is only 8-bit. 8-bit data is much coarser than 16-bit. Banding will most likely occur over flat areas of ground in 8-bit imagery. Here's how you can correct this:
- Go to "Image," "Adjustments," and select "Gradient Map." Make sure 'dithering' is enabled (either in the dialogue box or properties). This will apply the selected gradient over the entire range of values within your image resulting in a smoother, superior heightmap. *IMPORTANT* Choose appropriate colors for your lowest and highest values for your gradient map in the color boxes on the toolbar. I find that a total range of values between 10% and 35% gray (25 brightness values range) yields close to satisfactory results once you import into the GECK. Higher values = probably higher than Jacobstown, and lower = definitely underwater. This process might need to be repeated with different values to your liking and depending on the absolute values of your elevation in your DEM.
- *IMPORTANT* Export your correctly sized images in this format, exactly: 16-bit, grayscale, RAW, non-interleaved, IBM bit order. If everything is formatted correctly they will be 2 MB each. Anything else will likely crash the GECK. Name them according to the map above. The Mojave Wasteland does not cover a playable area in excess of four quads (I think...anything more just seems waaaaay too big, and who would want to spend time working on something that large anyway?)
- For importing large heightmaps (>2x2 quads) please check out TESAnnwyn. The GECK is a memory hog. We give what we can, but sometimes it just asks for too much.
...and you should be ready to import your images into the GECK!*
*The resulting heightmap is probably bumpy and looks noisy. However, the larger scale elevation changes are preserved. If one were to apply a blur effect to the image in photoshop you risk losing elevation data. HOWEVER applying a Gaussian blur with pixel radius of 1.0 and greater removes most noise. This was done to the heightmap data used in the example images.
Edited by TrickyVein, 07 December 2014 - 09:50 PM.