Abstract: This paper presents a ray tracing method based on the nearest points. Based on
rude point clouds, we employ a balanced binary tree to locate the nearest N points in setting range,
and employ grid structure to avoid unnecessarily iterative computation in point clouds space. The
intersecting computation is done between ray and local plane. To the actual nearest N’ points, the
normal of local plane is computed by triangle-area-weighted average computation of normals of
corresponding triangles, and we ensure coherence of computation of normal. Our method can
progressively render rude point clouds in multi-resolution mode by changing ray tracing
parameter (number of nearest points), and we set bigger number of nearest points to effectively
remove noise of rendering for point clouds with many noises, and we set smaller number of
nearest points to show more local geometry character for point clouds with less noise.

Key words: point clouds, ray tracing, the nearest N points, balanced binary tree