unrealistic mountains

[wackymidget]

Hi,

I'm generating a mountain range using a DEM file. I converted it to a ter file and from the ter file into a 16 bit sgi file. I use an image shader for the displacements projecting from a camera from the center of the earth. This way I can place it anywhere on the planet and rotate it as necessary. However, I get unrealistic round mountains. Using the ter file I do get rocklike mountains, but am unable to place it and rotate it where/how I want...

Using the ter file, I do get rocklike mountains.

Anyway to solve that?

[Roberts]

I think that  probably there is no more detail in your DEM and that is what makes your mountains look so round (more round than in reality). However, if your DEM is very detailed from the beginning, then that should of course also be reflected in your rendering. I myself have never used the kind of converting (DEM to sgi.file) that you describe so maybe something is happening in the conversion.

Also, looking at your second picture, the detail that is seen actually looks like fractal detail added by Terragen, not actual detail from the DEM.

Regards / Robert

[wackymidget]

Thanks for the quick reply Roberts.

Can anybody tell me (or refer me to) how I can add fractal detail?

Thanks.

[Matt]

The Heightfield Shader applies extra fractal detail, but the Image Map Shader doesn't. I don't think we have any ways of rotating the Heightfield Shader at the moment. It can't be warped using the Warp Shader, either, because it doesn't use texture coordinates.

Additional displacements can be applied using other shaders, such as the Power Fractal Shader, but they won't give the same results as the Heightfield Shader's built-in fractal detail.

Matt

[bigben]

The fractal detail settings that will give you the best results will depend largely on the resolution of your terrain, but it is worth playing around with them. As Matt said there is no real equivalent to the fractal detail applied to a heightfield. 

I've also found that if you want to use additional displacements it may be better to lower the amount of fractal detail applied to the heightfield (but not remove it completely).  For low resolution DEMs like the 90m resolution SRTM files, it can be quite tricky getting something that looks realistic.