> The big difference is ray casting is just along a line, not on every pixel. I think you have it backwards. Ray tracing is O(#of pixels*number of light bounce

> The big difference is ray casting is just along a line, not on every pixel. I think you have it backwards. Ray tracing is O(#of pixels*number of light bounces). More common 3D rendering is based on O(# of objects in the scene). It's conceivable that ray tracing can be more efficient for scenes with many objects.