This document discusses using ray tracing to perform visibility testing of voxel objects. It describes how ray tracing can be used to efficiently determine which voxel objects are visible without needing to render everything like with traditional occlusion culling. The key steps are: 1. Create a ray tracing buffer in GPU memory 2. Trace rays from pixels into a KD-tree of voxel objects to find the closest visible object 3. Record the object IDs in the buffer This approach is shown to perform faster than CPU occlusion culling by implementing it using CUDA on the GPU. Testing finds it can render frames at over 60 FPS even with large voxel worlds containing 50,000+ objects.