i have experimented with a different approach. instead of casting random rays in a hemisphere i render a 32x32 view (arc 160) at the normal and count the pixels with the color of the sky. the quality is much better and there is no noise but it's way too slow with 3dgs. i can't use render to texture because such textures don't allow to read pixels and bmap_for_screen is very limited for this purpose. maybe i will continue my experiments with opengl.