Normal offset smoothing

A ray tracing system for rendering an image of a 3-D scene, the ray tracing system comprising:

• a ray definition module configured to, based on an identified intersection between a ray and a planar primitive located in the 3-D scene, define a secondary ray to be emitted, the secondary ray having an origin which lies on an implicit surface associated with the planar primitive, wherein said intersection between the first ray and the planar primitive is at an intersection point, the origin of the secondary ray is determined as an offset from the intersection point and the offset of the origin of the secondary ray from the intersection point is along the incoming direction of the first ray;
• and
• at least one processing unit configured to process the secondary ray for use in rendering the image of the 3-D scene, wherein the implicit surface is a smooth curved surface;
• wherein the planar primitive is defined by a plurality of vertices located at the corners of the planar primitive;
• a respective vector is associated with each of the plurality of vertices defining the planar primitive;
• and the smooth curved implicit surface on which the origin of the secondary ray lies is defined by the vectors associated with the vertices of the planar primitive.

A non-transitory computer readable medium having stored thereon computer executable instructions, which when executed cause at least one processor to render an image of a 3-D scene by:

• in response to an identification of an intersection between a ray and a planar primitive located in the 3-D scene, emitting a secondary ray having an origin which lies on an implicit surface associated with the planar primitive, wherein said intersection between the first ray and the planar primitive is at an intersection point, the origin of the secondary ray is determined as an offset from the intersection point and the offset of the origin of the secondary ray from the intersection point is along the incoming direction of the first ray;
• and
• processing the secondary ray for use in rendering the image of the 3-D scene, wherein the implicit surface is a smooth curved surface;
• wherein the planar primitive is defined by a plurality of vertices located at the corners of the planar primitive;
• a respective vector is associated with each of the plurality of vertices defining the planar primitive;
• and the smooth curved implicit surface on which the origin of the secondary ray lies is defined by the vectors associated with the vertices of the planar primitive.