I’m currently working on a map which is surrounded by rocks (textures emperate_sd\rock_grayvar.tga). My idea was to create a skyportal with higher rocks using the same texture/shader to keep the look & feel of the map itself. So I tried to set up a skyportal with props_skyportal and _skybox but both attempts failed - HOM 
This was the reason for me to play around with terragen a bit to generate a skybox. Terragen gave me nice results very soon but after using the skybox with my map it looked boring. The rock texture in my map and the brownish terrain always looked too different. I wondered how I could give the skybox the look & feel of my map and found out that bmp- textures can be used by Terragen to render the terrain. I thought this could be useful for someone else so I’ll try to explain what you need.
First the software:
Terragen
SOPack plugins
TGPGUILib
If you don’t know how to generate a skybox with Terragen you might want to read this tuorial:
http://fps.brainerd.net/terragen.htm
Next you need a bmp picture (24 bit) for the Terragen terrain. For this example I converted textures emperate_sd\rock_grayvar.tga and textures emperate_sd\grass_dense1.tga to the Bitmap format.
Let’s go!
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Startup Terragen, generate or load an existing terrain.
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Open the landscape window (View --> Landscape)
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Click on the “Tex” and then on the “+” button and select “SO Image Overlay”


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After clicking “Edit”, the window “Set Image Overlay Options” appears.
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Click on “Select” and choose the bmp- image you converted from the original ET texture before. There are several options in this window worth to play with (terrain size and brightness for example).

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Click the “ok” button twice to accept the changes you made
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Render your terrain.
Finally, here are two examples:
texture: rock_grayvar / terrain size: 257x257 / tiles: 32x, 32y

texture: grass_dense1 / terrain size: 257x257 / tiles: 32x, 32y

Hope you like it 
Shaderman
