Hi; I finished doing my terrain occlusion system, and wanna know if any of u had done it like this... 0 - For each patch (chunk, node, or any name u use) of my terrain, I create an occlusion querie (HW). 1 - For each frame, after sorting front-back and fast frustum culling, i get the occlusion value(from the last frame, avoinding the stall of pipeline) of each visible patch,testing if was visible in previous frame. If yes, i start the occlusion querie, draw that patch as usual and stop that querie. If the patch wasnt visible last frame, i add it to a list of possible not visible patches. 2 - After rendering all visible patches, i loop throuhg the list of possible not visible patches, start the querie and draw only its bounding box (no color writes...), and stop the querie. 3 - go 1 I dont know if its a good way, but for non-flat terrains it works well, but for flat ones the overhead of occlusion functions its killing the performance....in FarCry they use a similar way, but i didnt find out how they do...even in wireframe they method works....maybe using a PVS could help (but no real-time deformation of course...)? Please comment your methods of culling... thanks!!!