Hello to you all!, I'm trying to render an island in real-time. For now I'm just searching the net for things to tell me how I should render this HUGE landscape. This terrain should be quiet detailed, but it I want it to able to be rendered at a low cost of CPU/GPU. I also hate loading points I rather avoid them. Far clipping is not an option, if the user should stand on the highest place on the island I want the user to be able to view the entire landscape. For example take Farcry, as far as I know the landscapes are quiet enormes! I'm looking for some fast alghoritms to implement this. I also want to create some indoor stuff, but that's somewhat out of my reach for now.. Can I use ROAM for this? Should I use paging? Please, can you give me a hand with this killer..? GBS [Edited by - GraphicsBas on March 12, 2005 10:52:55 AM]

Your main problem might be that you will require to have all the vertex data in memory if you want to get even close to RT. If you approximate an 4x4 km terrain with a rectangular grid of two triangles each meter you'll get ( even if textures are generated by the vertex shader ) at least ( considering 3D Verices with normals ) 384 Megabytes of Memory occupied only by the terrain ( Notice that you cann't allocate a Vertex Buffer Object of such a size ). ROAM would help you to decimate the amount of Vertices that need to be rendered but you still need that 384 MB Chunk on the CPU Memory ( A possibilty to reduce this would be to have ROAM (or others) approximate the highest LOD Mesh ).

However these days the vertex processor units are very fast while ROAM tends to be very Cpu-intensive. I suggest you should rather use less cpu-intensive approaches like GEO-MipMapping and __disable__ bump- and detailmaps as well as anisotropic filtering or other performace intensive rasterization-time operations for the meshes which are more far away.

ps: If you stand on the top of an Island and look down the framerate will be killed by the water calculations, and not by the terrain geometry - at least if you have realtime-calculated water.

I figured that about the memory cost.

I just looked at the Farcry terrain, it's quiet huge. I tried to see how big the detail was but I couldn't see it very well. I think the detail of the ground is very low. Like 10m a tile.

I didn't even think of bump mapping! Bumpmapping the terrain would be a total wast of time.

The water: for now I'm not concerned about the water. I will do the water when my terrain is finished. I also don't want to create very realistic water since it's not neccesary.

Should I create one heightmap for the entire terrain or should I cut the terrain into peases and for each pease have a sepperated heightmap?

Could you recommend me some papers or other stuff that might help?

GBS