Content | |
1. | Introduction |
2. | Users guide |
2.1. Parameters | |
2.2. Object and ray exclusions | |
2.3. Remarks on parameters and exclusions | |
2.4. Direct caching and parallel processing | |
3. | Some further implementation details |
The demo scene | The corresponding direct cache. |
-Dr (val) | The desired start value for the subcube sizes. The actual subcube
size depends on the size of the scene bounding cube because of the chosen octree refining procedure, so
the parameter is interpreted as an the upper limit. The algorithm tries to set a start value for the
subcube size being not greater than this. Remember that three steps of further
refining are possible, so the start resolution may well be rather coarse. If -Dr is not set,
by default the start value is determined automatically dependent on the scene bounding cube size,
resuting in -Dr = 0.10 m for scenes < 30 m -Dr = 0.15 m for scenes < 100 m and -Dr = 0.002 times the scene bounding cube sidelength for scenes > 100 m |
-Dt (val1, val1, val3) | The threshholds for relative illuminance variation which control further refining. Often, high settings suffice, allowing higher resolution only for the regions where really big illuminance differences occur. Default settings are 0.6, 1.7, 4.8. |
-Dv (val) | The (integer) number of test values used for the flexible resolution adjustment. The default setting is 4. It may happen that a big difference in illumination is not 'grasped' by the first 4 ray hits in a certain region, raising the number of testvals then helps in more accurately sample the local variation. (The feature is still somewhat experimental. The maximum value is dependent on the resolution and the internal storage handling, resulting in 16 for start refining depths of 7, 10 for depths of 8, 6 and 4 for depths 9 and 10. But the start refining depth depends on scene size and is not known a priori, so the value will be adjusted automatically if it is set too high.) A setting of 0 will disable flexible resolution adjustment. A setting of 1 makes no sense and therefore will be rejected. |
-Da (char) | General activation of the direct cache. 'o' switches off direct caching completely 'p' (preview) activates it for the direct calculation as well 'n' - the default - means normal mode, the cache is used for the ambient sample rays only. |
-Df (string) | Name of a file to write direct cache values to (or to read them in from a previous calculation). The start resolution parameter (-Dr) has to be the same in order to reuse the values from the file. If -Df is not set, no filewriting occurs (default). |
-Dn (val) | The allowed normal deviation (angle in degrees) for values from the cache to be used for the current rayhit. The default setting is 90 degrees. Of course, smaller values will lead to higher accuracy, but for the usual scenes the effect is negligible and not worth the more on time needed (less values can be reused, so more shadow rays are needed). The parameter is nevertheless kept for the sake of completeness. |
brdf_mat polygon tabletop 0 1 1 12 0.0 0.0 0.7 ... ... ... ... |
!genbox brdf_mat tabletop 0.5 1.0 0.02 -I 1 1 |
-Ds (val) | Supersample exclusion. This fraction (0 < Ds < 1) of all supersample rays will be treated with exact shadow testing. | |
-Dl (val) | the minimum raylength for the 'vicinity exclusion' mentioned above. If the first integer argument of an object is set to '1', ambient sample rays emerging from this object shorter than the -Dl setting won't use the direct cache. |