| 摘要 |
A Rendering system combines point sampling and volume sampling operations to produce rendering outputs. For example, to determine colour information for a surface location in a 3-D scene, one or more point sampling operations are conducted in a volume around the surface location, and one or more sampling operations of volumetric light transport data are performed farther from the surface location. A transition zone between point sampling and volume sampling can be provided, in which both point and volume sampling operations are conducted. Data obtained from point and volume sampling operations can be blended in determining colour information for the surface location. For example, point samples are obtained by tracing a ray for each point sample, to identify an intersection between another surface and the ray, to be shaded, and volume samples are obtained from nested 3-D grids of volume elements expressing light transport data at different levels of granularity. The volume sampling process uses ray tracing and sampling of light transport data volumetrically dispersed in 3-D space. It comprises tracing a ray in a direction from a point in s 3D scene up to a maximum distance of the transition zone and if no intersection was detected for the ray closer than a minimum distance of the transition zone then a conic section is marched through a 3-D grid of volume elements in the 3-D scene along the direction of the ray. Each volume element is associated with data representative of light energy propagating through surfaces of that volume element and the area of the conic section being marched is determined based on a spreading factor and a distance from the point in the 3-D scene to a current sampling point. Light energy is collected from the volume elements intersected by the conic section during the marching and lighting information is produced for the point in the 3-D scene from the collected light energy from the volume elements. |
