This process is repeated until the luminaire is finished. When the light is stopped, the light source generates another beam.
Keep an eye on how much light hits each surface.
The light is tracked with a two-dimensional arrangement that corresponds to the UV parameterization of the surface. Any surface can be used as long as there is a UV parameterization and the area per texel is known.
If an intersection point is reached, the value of the corresponding texel must be increased by the pro-color product of the light color with that of the surface.
Generation of texture maps for use in a rendering system.
Once a specified number of rays have been tracked from the light sources, the texture creation process can begin. Since the maximum value of a texel can depend on the number of light rays tracked in a scene, the values of the texels must be normalized to the maximum of each color. When overflowing the text set in the scene, the maximum values for each color component are determined. A second pass is performed to normalize each color value with the corresponding maximum. The value of the texel is also divided by its area.
The texture maps can then be saved and used to match the rendering system. We chose the real-time Ray Tracer developed by Steve Parker and Pete Shirley because we can use large amounts of texture memory. The files were stored in polygons and read in when the visualization was put into operation.
Only rectangular primitives were used to create our scenes. As already mentioned, other primitives with adequate UV parameterizations and known texel ranges such as Triangular Meshes or NURBS could be used.
Since this is a scene that depends on an even distribution of the random rays, the quality of the textures increases with the number of rays per texel. This helps to reduce the speckles below. For good results, 100 to 1,000 rays per texel are recommended.
Although it is an “offline” preprocessing, it can be quite time consuming to generate these texture maps. With a naive implementation on an Origin 3000, it took 240 working hours to track 100 million rays with a scene of 2.2 million textiles.
This is an uncomplicated implementation for global lighting. In contrast to calculating the form factor, which scales O (n^2) based on the number of discrete surfaces, this approach scales around the cost of calculating crossings with the primitive. By using optimizations of raytracing, such as a limited hierarchy, scaling to O (n log n) can be done.