You will need the following:
- Google Earth (http://earth.google.com)
- MicroDem (http://www.usna.edu/Users/oceano/pguth/website/microdem.htm)
- SRTM Overlay for GoogleEarth (Run from URL once you’ve installed Google Earth - http://www.ambiotek.com/topoview).
- An image editing package capable of saving as (preferably) .TIFF and capable of resizing an image with minimum damage.
- DispGen (http://www.chaosincarnate.net/cannonfodder/cftools.php?program=dispgen)
** Google Earth Section **
Load up google earth and find the area you want to sample heightmap data from.
Double click your icon for the SRTM Overlay, where-ever you saved it. (Should be called srtm41.kmz)
Make sure you have “elevation” checked in the google earth “Places” drop down.
The world should have been split into boxes with little green mountains in the middle. Find the box that goes around around the area you want and click it’s green mountain icon.
In the popup that appears scroll down and download the ARCASCII file from the mirror closest to you.
Close Google earth.
** MicroDEM Section **
Unzip the files you just downloaded to somewhere you can remember.
Load up MicroDem
File > Open > Open DEM > ASCII Arc Grid (.asc), then in the window that opens navigate to the place you unzipped the data and load the .asc file.
The image has a load of junk on it we don’t need.
Right click the image, select “Legends / Marginalia”, and untick the boxes next to Elevations, Scale bar, Terrain Categories and Database legends. Click OK.
Now we need to select the area we want. On the toolbar at the top of the data window (not the main toolbar, the one at top of the currently open heightmap window.) select the Crop tool (small dotted rectangle with an arrow in the bottom right corner) and drag it over the area you want. If you make a mistake with this step use the button to the right of the crop tool to undo it.
Now to turn it into a usable heightmap. Right click your open map and choose “Display Parameter” and from the popup choose “Elevation”.
Select “Gray scale” from the list of options.
7.The other option you might want to mess around with is “Z Range”, which controls the minimum and maximum height of the heightmap, **although it’s probably best to leave it at default and not touch it unless you know what you’re doing. **
Click OK and let the map redraw.
Final step in MicroDem. We have to resize the map to 1:1 pixel mapping. This is a simple step, just click the icon between the zoom in and zoom out buttons. (It’s a magnifying glass with a 1 in it.)
If your map gets a grid over it, right-click it and choose “Grids/Graticule” and set the “Grid” option to "Neither"
- We need to export to .TIFF. Click File > Save Map as Image > “GeoTiff Screen scale (color)”. Save it wherever you want.
** Photoshop Section (try to follow along in your own software if you don’t have photoshop) **
Load up the .tiff file. File > open.
We need to resize the image to a power of two (Not sure if this is required, but it will be neater and will likely cause less problems.)
Go to Image>Image Size>, select pixels from the drop down and type in a power of two combination (1024, 1024. 512, 1024 etc.)
Once you’ve done that (and hopefully not lost too much image quality) save it back out as a .Tiff. It isn’t that important if it isn’t a .tiff, Dispgen just prefers it.
** DispGen Section **
** This section requires a lot of trial and error! **
Load up DispGen.
Set the size and height of your land, preferably in powers of two again, in the X Size, Y Size and Height boxes. Does NOT have to be the same size as the heightmap image.
Set the X Triangles and Y Triangles boxes to about 128, that’s always done me fine. If you can squeeze a bit more detail in, set them to 256.
Leave “Adjust Terrain to minimize vertical stretching” turned off for now. If you have stretching problems (and aren’t using $seamless_scale textures) then try turning it on.
Load the heightmap file, leave smoothing off for now, see what it’s like without and adjust it 'till it looks okay.
If you know the texture you’ll be using on the land then enter it here, if not just leave it for now.
A neat feature that saves a lot of time is the “Blend By Slope” option.
I usually set “img_thumbn Angle” to 35 and “Transition Degrees” to 45. If this doesn’t work well for you try raising/lowering it by 10 each time.
Choose where to output the VMF file and tick Create VIS Nodraws!
** Hammer Editor Section **
- Load it up the generated vmf in hammer and see what it’s like. If it’s wrong adjust smoothing, sizes and such in DispGen and try again and again 'till you’re happy with it.