CHANGELOG.md

Version History

Open PGL 0.6.0

• Api changes:

  • Device added numThread parameter (default = 0) to the constructor to set the number of threads used by Open PGL during training. The default value of 0 uses all threads provided by TBB. If the renderer uses TBB as well and regulates the thread count this count is also used by Open PGL.
  • SurfaceSamplingDistribution and VolumeSamplingDistribution:
    • Added GetId function to return the unique id of the spatial structure used to query the sampling distriubtion.
  • Field and SampleStorage, added Compare function to check if the data stored in different instances (e.g., generated by two separate runs) are similar (i.e., same spatial subdivisions and directional distributions).
  • Field:
    • The constructor of the Field class now takes a FieldConfig instead of a PGLFieldArguments object. (BREAKING API CHANGE)
    • GetSurfaceStatistics and GetVolumeStatistics functions are added to query statistics about the surface and volume guiding field. The functions return a FieldStatistics object. Note, querying the statistics of a Field introduces a small overhead.
  • FieldStatistics:
    • This class store different statistics about a Field, such as, number and size of spatial nodes, statistics about the directional distributions, and the times spend for full and separate steps of the last Update step. The statistics can be queried as a full string (useful for logging) or as CSV strings (useful for analysis and plotting).
    • ToString: Returns a string printing all statistics.
    • HeaderCSVString: Returns the CSV header sting with the names of each statistic.
    • ToCSVString: Returns the CSV value sting of each statistic.
  • FieldConfig:
    • This class is added to replace the PGLFieldArguments struct when using the C++ API. -Init: the function initializes the parameters of the FieldConfig (i.e., similar to pglFieldArgumentsSetDefaults). Additional parameters (deterministic and maxSamplesPerLeaf) are introduced to enable deterministic behavior and to control the spatial subdivision granularity. -SetSpatialStructureArgMaxDepth: this function can be called after Init to the the maximum tree depth of the spatial structure.
  • pglFieldArgumentsSetDefaults: Adding two additional parameters deterministic and maxSamplesPerLeaf. (BREAKING API CHANGE)

• Tools:

  • Added a set of command line tools which are build when enabling the OPENPGL_BUILD_TOOLS Cmake flag.
    • openpgl_bench: Tool to time different components of Open PGL such as the full training of a Field or the querying (initialization) of SamplingDistributions.
    • openpgl_debug: Tool to validate and compare stored SampleStorage and Field objects or retrain a Field from scratch using multiple stored sets (iterations) of stored samples.

• Optimizations:

  • Spatial structure (Kd-tree) build is now fully multithreaded. This improves training performance on machines with higher core counts, especially when using deterministic training.
  • Kd-tree switched to use cache-friendlier TreeLets instead of single TreeNode structures.

• Bugfixes:

  • Field fixed some non-deterministic behavior when spatial cache does not receive any training data during a training iteration due to a large number of training iterations.
  • Removed legacy/broken support for OpenMP threading since there is a dependency to TBB anyway.
  • Fixed build problems on (non-Mac) ARM systems.

Open PGL 0.5.0

• Api changes:

  • PathSegmentStorage:

    • Removed support for splatting training samples due to the fact that knn-lookups have proven to be better. Therefore, the function attributes splatSamples and sampler have been removed from the PrepareSamples function.

    • Added PropagateSamples method prepare and push samples to the SampleStorage The goal is to replace PrepareSamples, GetSamples and AddSamples.

  • Sampler:

    • Removed since it is not used/needed anymore.

  • SurfaceSamplingDistribution and VolumeSamplingDistribution:

    • The usage of parallax-compensation is now connected to the guiding distribution type. Therefore the explicit useParallaxCompensation parameter is removed from the Init functions of the SamplingDistributions.
    • Added IncomingRadiancePDF function that returns an approximation of the incoming radiance distribution. This PDF does not need to be related to the actual sampling PDF but can be used for Resampled Importance Sampling (RIS).

  • Field:

    • Adding UpdateSurface and UpdateVolume function to update/train the surface and volume field separately.

  • SampleStorage:

    • Adding ClearSurface and ClearVolume function to clear the surface and volume samples separately. This allows to wait until a specific number of samples is collected for the surface or volume cache before updating/fitting the Field.

• Deactivating/removing OMP threading support since it would still have a dependency on TBB

• Bugfixes:

  • Fixing bug causing crash during Field::Update when in previous iterations no volume or surface samples were present.

Open PGL 0.4.1

• Bugfixes:
  • Fixing bug introduced in 0.4.0 when using ApplySingleLobeHenyeyGreensteinProduct() for VMM-based representations

Open PGL 0.4.0

• Performance:

  • Optimized KNN lookup of guiding caches (x3 speed-up).
  • Optimized Cosine product for VMM based representations.

• Dependencies:

  • Removed the Embree library dependency for KNN lookups in favour of the header-only library nanoflann.

• Adding ARM Neon support (e.g., Apple M1).

• Fixing memory alignment bug for higher SIMD widths.

• PathSegmentStorage:

  • Fixing bug when multiple refracted/reflected events hit a distant source (i.e., environment map) by clamping to a max distance.
  • Adding GetMaxDistance and SetMaxDistance methods.
  • Adding GetNumSegments and GetNumSamples methods.

• Field:

  • Stopped tracing a total number of spp statistic since it is not really useful.
    • Removed the GetTotalSPP function.
    • Removed the numPerPixelSamples parameter from the Update function.

Open PGL 0.3.1

• Field:

  • Added Reset() function to reset a guiding field (e.g., when the lighting or the scene geometry changed)

• PathSegmentStorage:

  • Fixed bug when using AddSample()

Open PGL 0.3.0

• Added CMake Superbuild script to build Open PGL, including all its dependencies.
  The dependencies (e.g., TBB and Embree) are downloaded, built, and installed automatically.

• Added support for different SIMD optimizations (SSE, AVX2, AVX-512). The optimization type can be chosen when initializing the Device.

• Added support for directional quadtrees for the directional representation.

• PathSegmentStorage:

  • Added debug function CalculatePixelEstimate to validate if the stored path segment information represents the sampling behavior of the render (i.e., the resulting RGB value should match the pixel value the renderer adds to the framebuffer)

• SurfaceSamplingDistribution:

  • Added support for guiding based on the product of a normal-oriented cosine lobe and the incident radiance distribution: (ApplyCosineProduct) This feature is only supported for VMM-based directional distributions. Support can be checked with SupportsApplyCosineProduct().

• VolumeSamplingDistribution:

  • Added support for guiding based on the product of a single lobe HG phase function and the incident radiance distribution: ApplySingleLobeHenyeyGreensteinProduct() This feature is only supported for VMM-based directional distributions. Support can be checked with SupportsApplySingleLobeHenyeyGreensteinProduct().

Open PGL 0.1.0

• Initial release of Open PGL Features:

  • Incremental learning/updating of a 5D spatio-directional radiance field from radiance samples (see Field).
  • Directional representation based on (parallax-aware) von Mises-Fisher mixtures.
  • PathSegmentStorage is a utility class to help keep track of all path segment information and generate radiance samples when a path/random walk is finished/terminated.
  • Support for guided importance sampling of directions on surfaces (see SurfaceSamplingDistribution) and inside volumes (see VolumeSamplingDistribution)

• Added C-API and C++-API headers

  • C-API: #include <openpgl/openpgl.h>
  • C++-API: #include <openpgl/cpp/OpenPGL.h> and the namespace openpgl::cpp::