Function interp_surface_normal_from_ray_tracing_results

plib/render.py:182–222

Interpolate the surface normal of the intersection points using surface normal on the vertices. Args: mesh: raycast_results: the output of ray casting of o3d Returns: (*, 3) surface normal. Note that it fills in a random value if a ray does not hit

(
        mesh: o3d.geometry.TriangleMesh,
        raycast_results: T.Dict[str, T.Any],
)

def interp_surface_normal_from_ray_tracing_results(
        mesh: o3d.geometry.TriangleMesh,
        raycast_results: T.Dict[str, T.Any],
) -> np.ndarray:
    """
    Interpolate the surface normal of the intersection points using surface normal on the vertices.

    Args:
        mesh:
        raycast_results:
            the output of ray casting of o3d

    Returns:
        (*, 3) surface normal.  Note that it fills in a random value if a ray does not hit a surface

    """
    if not mesh.has_vertex_normals():
        return raycast_results['primitive_normals'].numpy()  # (*,3)

    # barycentric coordinates of the intersection in the intersected triangle
    barycentric_coords = raycast_results['primitive_uvs'].numpy()  # (h,w,2), the third weight is 1-sum()
    barycentric_coords = np.concatenate(
        (1 - np.sum(barycentric_coords, axis=-1, keepdims=True), barycentric_coords),
        # note that in open 3d, the primitive_uvs indicates last two coordinates rather than first two
        # (barycentric_coords, 1 - np.sum(barycentric_coords, axis=-1, keepdims=True)),
        axis=-1,
    )  # (h,w,3)

    # the intersected triangle index
    primitive_ids = raycast_results['primitive_ids'].numpy()  # (h, w)
    # fillin a dummy primitive_id for the rays that go to inf
    primitive_ids[primitive_ids == o3d.t.geometry.RaycastingScene.INVALID_ID] = 0  # (h, w)

    # get triangle vertex
    triangle_vidxs = np.asarray(mesh.triangles)  # (n_triangle, 3)  index of vertices
    vertex_normals = np.asarray(mesh.vertex_normals)  # (n_vertex, 3)  surface normal of each vertex

    vidxs = triangle_vidxs[primitive_ids]  # (h, w, 3)  the vertex id of each camera ray
    v_normals = vertex_normals[vidxs]  # (h, w, 3, 3)  last dimension is normal (dx, dy, dz)
    interped_normals = np.sum(np.expand_dims(barycentric_coords, axis=-1) * v_normals, axis=-2)  # (h, w, 3)
    return interped_normals


def rasterize(