Welcome to RenderMan Pro Server 16!

This release represents another significant milestone for global illumination and re-rendering with PRMan. We've greatly increased the efficiency of global illumination, both in terms of raw performance and thread scalability as well as in memory consumption. We've also introduced new RSL support to make writing physically plausible shaders easier and more efficient than ever, described in detail in a new application note.

A new raytrace hider has been added that allows you to bypass the REYES front-end and directly trace primary rays. It has application in both interactive and final-quality rendering. The raytrace hider is well suited for a subset of rendering applications where scene complexity doesn't exceed system memory. As a re-renderer, it is attractive for lookdev and previs applications due to its low startup cost and support for a broader range of scene edits. As a final-frame renderer, it supports esoteric sampling effects due to its arbitrary camera projection and full temporal shading. For final-quality relighting applications, the REYES re-renderer (a.k.a. "Lumiere") remains attractive due to its scalability and support for partial recomputation. Both re-renderers now support shader-instance edits, while the raytrace re-renderer alone supports camera edits.

Ray-traced shadows have been greatly improved through a combination of low-level improvements and the addition of new RSL function, areashadow. The new function better expresses the underlying shadowing requirements to the renderer, which often results in larger ray bundles and therefore significant speed gains. The areashadow() function supports tracing directly into the scene and the tracing of deep shadow files. Traceable deep shadows offer an advantage over direct scene tracing by reducing the memory overhead associated with a scene by leveraging rasterization and texture-caching. Rasterization carries with it some disadvantages, though, so you'll need to carefully evaluate the tradeoff between direct and deep-shadow modes. Because of the potential speedups and expressivity associated with areashadow(), we recommend that current uses of the transmission() function be evaluated for conversion.

New controls to reduce costs associated with ray-traced displacements and to automatically simplify ray-traced geometry introduce new acceleration and memory-reduction opportunities. A new shading mode also allows shaders to selectively replace ray-hit shading with texture3d lookups.

To round out the set of ray tracing improvements, we are introducing a new Application Note, The Importance of Importance. The single most significant control over the cost of ray tracing in PRMan is the number of rays your shaders choose to cast. In this appnote we describe some of the well-known tricks to prune the potentially large ray trees that recursive ray tracing algorithms can produce too easily. We hope that presenting this information in an easily digested, RSL-centric form will encourage you to employ these tricks in your production shaders.

While these new features and optimizations make ray tracing ever more attractive, the REYES (a.k.a. stochastic) hider can still be significantly more efficient in memory consumption, displacement shading, and motion blur speed. Certain non-physical lens and shading effects are only possible with the REYES hider, while other physical effects may only be possible with the raytrace hider. Our hybrid REYES/rays architecture lets you select the sweet spot for your shot or show.

Of course, no RPS release would be complete without a large collection of general improvements and we're pleased to offer a bumper crop in version 16.

In the realm of point-based techniques, we've added support for the baking of spherical harmonic visibility. This can be coupled with a new txmake environment map encoding to produce fast low-frequency environment lighting. A new getpoints() RSL function provides direct access to data stored in point cloud files. We've also implemented the long-requested "worldspace" dicing mode in this release to simplify baking pipelines.

A number of extensions to our deep texture file format and subsystems have been made in this release. We've extended the file format and output driver to support deep compositing, allowing you to deliver rgba data directly into deep texture files. We've generalized the dtex file format to support multiple subimages in a single deep texture file; each subimage can be comprised of any number of channels and have its own image resolution and coordinate systems. We've written example deep-compositing applications built atop our new RixDeepTexture API. This new C++ API will be available in the form of a freely redistributable shared library, librix.so/dll. We hope that this combination of enhancements and APIs will help to promote a standard multi-view deep compositing workflow like that pioneered by the folks at Weta Digital. We've also added a new deep method, areashadow, that produces the deep texture data suitable for use by the new areashadow RSL function. Also, traditional deepopacity files will be significantly smaller due to an improved compression technique.

A new texture-synthesis plugin type has been added that allows plugins to deliver texture data directly to PRMan's texture cache, where it is automatically antialiased for delivery to shaders via the texture() RSL function. A texture plugin is provided with this release that allows you to treat SVG files (a standard vector image format) like standard pixel-based textures. The SVG plugin allows you to deliver arbitrarily high texture resolution without paying the usual penalties of disk-space and I/O. We've also completely overhauled our texture-conversion subsystem, txmake, and can now convert ultra-high resolution textures on multi-core CPUs very efficiently.

We've generalized support for multi-segment motion blur by removing the venerable 6-sample limit and by adding support for multi-segment camera blurs. We've introduced a new shading strategy in which a single shading result can be reused across all motion segments.

Volume support continues to improve in RPS 16. We've extended the RiVolume primitive to support ImplicitField plugins and significantly sped up the ray tracing speed.

In the shading subsystem, we've implemented a just-in-time (JIT) optimizer for .slo files. At load-time, we specialize shader function invocation according to context and retarget code to special SSE-optimized variants in some conditions. On typical scenes we've seen 20% speedups due to this optimization. We've also added a new pattern generation RSL function, knoise, a variation of the Gabor Noise presented Siggraph 2009. Finally, RPS 16 introduces the beginnings of a new stdrsl library of shader functions that we intend to grow over time. Distinct from our previous hodgepodge of RSL source examples and toy shaders, the stdrsl shader library is intended to be a true resource for your production shaders. Our first release includes support for SphericalHarmonics.h and AreaSamplers.h.

Details of the release are enumerated below.

Ray Tracing and Re-rendering

• Raytrace Hider

  A new raytrace hider has been implemented, allowing users to bypass the REYES front-end and trace primary rays directly, for both re-rendering and final frame renders.

  The PRMan distribution includes a new RiFilter, RifRayTraceHider.so/dll, which can be used to render scenes via the raytrace hider, e.g., like so:

  prman -rif RifRayTraceHider.so in.rib
  prman -rif RifRayTraceHider.so -rifargs -mode adaptive -minsamples 5 -variance 0.01 -rifend in.rib
  

• Multiresolution Radiosity Cache

  There is a new radiosity cache that provides substantial speedups for indirect illumination computed by indirectdiffuse() and gather(), as well as shader-evaluated transmission in occlusion() and transmission(). Storing diffuse color values and/or opacities in this new cache can provide speedups as much as 40x. The cache is on by default, but can be turned off by setting Option "limits" "int radiositycachememory" (or in the rendermn.ini by setting /prman/raytrace/radiositycachememory) to 0. The default cache size is 100MB.

  Additionally, this new feature provides significant speedups for multi-bounce global illumination. Please consult the Global Illumination application note for additional information.

  A new performance warning has been added to signal radiosity cache thrashing. The threshold value that triggers the warning can be controlled via a rendermn.ini setting:

  /prman/statistics/radioevictwarnratio
  

• New Integrators for Physically Plausible Lighting

  There are two new integrator functions in RSL - directlighting() and indirectspecular() - and a new application note, Physically Plausible Shading in RSL to motivate them.

• New RSL Pipeline Methods

  The lighting method has now been further atomized into diffuselighting and specularlighting methods. Using these optional methods will maximize the benefits of the new Multiresolution Radiosity Cache.

• New Sample-Generating Functions

  There are four new sample-generating functions in RSL - generateSampleAS(), evaluateSamplesAS(), generateSamplesEnv(), evaluateSamplesEnv() - that make writing physically plausible shaders that interoperate with the new integrators easy as PI.

• New Physically Plausible Shaders

  There are several new reference shaders built atop the new integrators, pipeline methods, and sample generation functions.These can be found in $RMANTREE/lib/rsl/shaders/stdrsl.

• New areashadow() RSL function

  • PRMan now supports both ray-traced shadows as well as traceable deep shadow maps, via the areashadow() function.
  • Traceable deep shadowmaps can be produced with a new deep method, areashadow. The opacity threshold attribute can be used to control the number of layers present in the file. Traceable deep shadows provide fast, high quality soft shadowing with numerous benefits over traditional deep shadows and ray-traced shadows.
  • There is a new Area Shadowing application note, for more information.

• New Re-rendering Features

  There are a number of improvements to PRMan's re-rendering technology:

  • Ray Tracing Renderer: we've introduced a ray-traced re-rendering mode. The choice between the re-renderers is governed by new parameters of RiEditWorldBegin(): "string rerenderer" "raytrace|reyes". Each re-renderer has its strengths, and careful consideration is due when choosing.
  • Shader instance edits: both re-renderers now support shader edits.
  • Camera edits: the ray tracing re-renderer now supports camera edits.
  • Edit API modifications: we've simplified the interface for editing shader instances, RenderMan Attributes and shader bindings and RenderMan Options.
  • Limitations lifted: support for RiBlobby implicit surfaces has been added, Imager and Visible Point shaders are executed during re-rendering, and support for editing co-shaders has been expanded.
  • New examples: Python-based examples are provided in our distribution in the directory: $RMANTREE/lib/examples/rerender.

• New Ray Accelerator

  Once again, ray tracing has been sped up, and memory consumption when ray tracing has been reduced. transmission() rays, in particular, should be faster, especially when shaders are executed to determine the opacity at shadow ray hit points.

• New Ray Type Control

  There is a new parameter for gather(), indirectdiffuse(), occlusion(), and trace(): "string type". Valid values are "specular", "diffuse", and "transmission". This new parameter allows explicitly setting the ray type. If the type isn't specified, there is a default type for each function. The default types are:

• New Shading Modes

  A new shading hitmode has been added that allows the specification of a 3D texture file (point cloud or brick map) as a source for color and opacity at ray-hit points. This can greatly accelerate multibounce diffuse and transmission shading by eliminating the per-hit shading overhead.

  Attribute "shade" "string diffusehitmode" "cache"
  Attribute "shade" "string diffusehitcache" "file:/path/to/texture3d"
  Attribute "shade" "string transmissionhitmode" "cache"
  Attribute "shade" "string transmissionhitcache" "file:/path/to/texture3d"
  

  The occlusion, indirectdiffuse, transmission, and areashadow RSL functions accept the "hitmode" and "filename" parameters, and these always take precedence over the Ri attribute.

  Additionally, users can specify the diffusehit channels via:

  Attribute "shade" "string diffusehitcolorchannel" [""]
  Attribute "shade" "string diffusehitopacitychannel" [""]
  

• More Efficient Traced Displacements

  There is a new attribute value:

  Attribute "trace" "int displacements" [2]
  

  As before, 0 means don't displace anything for ray tracing and 1 means displace everything (that's displaced) when ray tracing. The new value, 2, tells the renderer to only displace the finest resolution.

• Geometry Decimation Controls

  There is a new option that offers control over the tessellation of ray-traced surfaces that can be used to provide significant speedups:

  Option "trace" "float decimationrate"
  

  Useful values are 1, 2, 4, 16. 1 signifies no decimation; the other values increase the simplification over the highest-fidelity (Reyes) tessellation.

  This gives speed-ups in these places:

  1. The intersection tests themselves are faster since fewer quads/tris need to be hit tested.
  2. The number of lookups in the fine tessellation cache is reduced.
  3. Overall tessellation cache traffic is reduced.
  4. For "decimationrate" 2 and 4, the max size of each entry in the fine tessellation cache is smaller, so the same cache memory can hold more cache entries. Under certain circumstances, the fine tessellation cache can be avoided entirely.
  5. For "decimationrate" 16 and higher, there is no need for the fine and medium tessellation caches, so that memory is used instead to increase the capacity of the coarse tessellation cache.

  The speedup can be up to 25% in scenes where raw ray tracing speed dominates (e.g. ambient occlusion).

• New Importance Sampling Application Note

  A new application note, The Importance of Importance, has been added, outlining shader techniques for optimizing ray tracing.

• Tessellation optimizations have resulted in faster ray tracing of displaced surfaces.

• The number of hemisphere rays shot by the ray-traced occlusion() and indirectdiffuse() functions from a given single point is no longer clamped to 10,000. That said, 10,000 is a very big number, so PRMan will now warn you if you exceed that very big number.

• Ray tracing of LOD geometry has been improved. Prior to this change, PRMan used the screen-size-based Reyes LOD for ray tracing. Now PRMan uses ray differentials to choose a coarser LOD for ray tracing when appropriate.

New Point-Based Rendering Features

• Spherical Harmonic Visiblity: ptfilter can now compute a spherical harmonic (SH) representation of the directional visibility or incident radiance at each point.

  ptfilter -filter occlusion -shbands N ...
  

  or:

  ptfilter -filter [volume]colorbleeding -shbands N ...
  

  The default for -shbands is 0 which means that no computation is done. The resulting point cloud contains an array of floats called "_dirvisshcoeffs". There are N^2 elements in the array. There is a new Application Note, Image-Based Relighting, that delves deeper into the usage of this new feature.

• New ptfilter filter: simplify

  The new ptfilter filter, simplify, takes four parameters: maxdist, mindot, maxdiff, and rasterspace. It reads one or more point cloud files, and iteratively merges points that are closer than maxdist and have normals that point more than mindot in the same direction. The default value for maxdist is 1e15. With this huge default value for maxdist, all points with similar normals will be merged, so it is imperative that a value that is more appropriate for the scene is specified. The default value for mindot is 0.5. The parameter maxdiff tells ptfilter not to merge points if their data differ by more than the specified amount; the default is 1e15. Note that maxdiff does not apply to data channels with names containing "area" or "Area". The last parameter is rasterorient 0|1, which tells ptfilter to measure maxdist in pixel units rather than world space coordinates (the default, 0, is off).

• getpoints()

  PRMan 16 introduces a new function, getpoints(), that reads point data from a point cloud, frame cache, or grid cache, and returns the number of points found.

• ptfilter -photonmap is now multithreaded.

• ptfilter's -maxsolidangle and the subsurface() function's maxsolidangle default value has been changed from 1.0 to 0.1, matching the default value in occlusion() and indirectdiffuse(). This means that the computations will be slower (but also more accurate) by default.

• Multithreaded load balancing has been improved for ptfilter when used for subsurface scattering, occlusion, colorbleeding, and volume colorbleeding.

• Point-based color bleeding and occlusion calculations have been sped up by 10-20%.

Motion Blur Enhancements

• There are no longer restrictions on the number of segments for world multi-segment motion blur.

• Camera multi-segment motion blur (i.e: multi-segment motion blur specified before WorldBegin) is now supported.

• For multi-segment motion blur, users can now choose to shade once per motion segment or once per frame, via a new attribute:

  Attribute "shade" "string frequency" ["frame"|"motionsegment"]
  

• Ray tracing of multi-segment motion blur is much more accurate.

• Motion-blurred objects that are moving extremely quickly through the camera are now faster and more memory efficient to render.

• Motion blocks specifying transform blur that do not include shutter boundaries now work correctly.

• The specification of dPdtime-based motion blur for RiVolume has changed.

New Deep Compositing Features

• Deep AOVs: we've extended our deep texture file format to support the deep compositing applications. The more general format now supports multiple subimages, each of which can contain AOV data. A stereo, deep compositing application RIB files would output deep color and alpha data with RIB like this:

  DisplayChannel "rightCi" ...
  DisplayChannel "righta" ...
  Display "scene.dtex" "deepshad" "rgba"
  Display "+scene.dtex" "deepshad" "rightCi,righta"
  

  Deep texture files created in this fashion can also be used as holdout mattes for 2D compositing via a new RiOption, Hider "hidden" "string mattefile", and can now be used to perform depth masking via the depthmask hider. Note that the depthmask hider only treats deep texture files at pixel resolution and will therefore not have subpixel accuracy, meaning a higher depthbias value may be required to avoid artifacts.

• C++ Deep Texture API: we've deprecated the C-binding of the dtex API in favor of a new C++ binding to the same functionality. The new library delivers a cleaner set of controls and queries and provides access to new subimage and multichannel support.

  • The RixDeepTextureMerge.cpp example demonstrates how to combine two or more deep texture files into a new file.
  • The new DeepPixel::Composite method flattens a deep pixel into the final rgba form.
  • The new DeepPixel::Merge method combines pixels to perform a correct depth composite.

• There is a new Deep Compositing Application Note that provides a closer look at these features.

New Procedural Texture Plugin

We now support texture synthesis plugins to deliver arbitrary texel data to our texture cache subsystem. Plugins respond to renderer requests to fill texel buffers that are delivered in an automatically antialiased form to consumers of plugin via the texture RSL function. Arguments to the plugin are encoded in the filename argument using standard web URI syntax to support a combination of standard and plugin-specific parameters.

• New RtxPlugin API: describes the new Rtx API and provides example plugins.
• SVG Texture Support: RPS 16 ships with a full-features SVG renderer plugin based on the web-standard rsvg open-source libraries. This plugin accepts the name of an .svg file and can deliver ultra-high resolution renderings with minimal I/O and diskspace requirements.

New stdrsl Library

We now provide RSL code intended for inclusion by your production shaders. The stdrsl shader library is a collection of supported RSL code that leverages the expressiveness of RSL structs and centralizes the computation of various standard computations. The RSL source can be found below $RMANTREE/lib/rsl/include/stdrsl. The shader compiler is aware of this special location and so clients should refer to stdrsl components as follows:

#include <stdrsl/SphericalHarmonics.h>

New librix

A new library has been developed that exposes a subset of our standard APIs to a broader range of users. The intention is to facilitate the use of our standard file formats by pipeline tools other than our own. A version of librix will be loosely coupled with an RPS release in the usual sense: features present in a new release of RPS will only be available via the associated librix. Tools linked against older versions of librix should be forward-compatible with future RenderMan versions but with limited access to new features. We've also packaged librix as a separately downloadable library and plan to license certain of these libraries under very liberal terms.

C++ Binding for RIB Generator

A dependency-free library to write RenderMan-standard RIB files based on a simple C++ extension to the venerable C-binding.

DeepTexture API

A new C++ binding to read, write, and modify deep texture files. Deep compositing applications should be able to build solutions atop this library.

Subdiv API

An implementation of Pixar's subdivision surface technology. This API allows you to subdivide geometric meshes in a way that is 100 percent compatible with PRMan's implemention. It can be used to integrate Ptex workflows into paint packages, and for other special effects.

Additional Enhancements and Changes

Bug Fixes

• The RxOption, RxAttribute, RxTextureInfo, and RxRendererInfo now consistently return a resultcount of 1 for scalar queries. NOTE: This might result in changes in plugin behavior.
• The value of s/t on RiBlobbies is now computed, correctly, as P.x/P.y in object space, which matches the default parameterization of polygons and volumes.
• Fixed a bug in the computation of gather() ray differentials at shading points where the gather main direction is close to (0,0,-1) and the coneangle is > 0. This bug could cause artifacts when using an environment call in a gather loop.
• ptexture() now accepts "catmull-rom" and "b-spline" as texture settings, as well as "catmullrom" and "bspline".
• EditBegin now behaves properly within IfBegin/End blocks.
• MakeBrickmap throws a warning, rather than an error, if the input file is not found
• Fixed a bug with OpenEXR environment maps where longitude was off by 180 degrees when determining importances.
• Fixed a bug that caused incorrect results for point-based occlusion, color bleeding, or volume color bleeding, when passing a uniform P or N.
• "pointfalloff" is now applied to color or transparency AOV channels.
• Fixed a bug in volume renders that could inadvertently set the color to black.
• Fixed a bug that could cause incorrect shading interpolation on long curves with many knots.
• Fixed a bug caused by dPdtime not being transformed to object space before being applied to an object space bounding box.
• Fixed a bug that could lead to incorrect point clouds being generated when using refinement() on doubleshaded surfaces.
• Struct constructors can now use inherited member initializers.
• Fixed a bug that prevented struct definitions from being properly reset when using the Slo API.
• Fixed a long-standing bug that could lead to artifacts when using asymmetric PixelSamples in conjunction with Depth of Field.
• Fixed a bug that could lead to variable (resizeable) length arrays being initialized improperly.
• The lens aperture parameter in the stochastic hider now produces properly-oriented results.
• A ray tracing issue that could prevent geometry from being unloaded properly has been fixed.
• An issue with displacement bounds that could lead to slower volume rendering has been addressed.
• Fixed an RiVolume transmission() bug that could cause artifacts.
• Addressed a (Windows-only) bug that prevented > 4GB output for point clouds.
• A bug in gather() that could cause artifacts when ray tracing against partially transparent objects has been fixed.
• Fixed a bug that could lead to artifacts when using large blurs with filter regions.
• Fixed a bug with computing filter regions on uniform values that could occasionally cause corrupted values.
• Addressed a bug in filter regions that could lead to NaNs when calculated for degenerate geometry with orientation invariant dicing.
• Addressed a ray tracing precision issue that could lead to incorrectly missed hits and subsequently to missing mesh faces.
• Addressed a longstanding issue that prevented RiParaboloid from motion blurring properly.
• Addressed timer errors on 64-bit Windows.
• Fixed a Windows-only bug that prevented the use of absolute file pathnames in the style C:\file\pathname.
• Several bugs in object instancing have been addressed.
• Various memory leaks have been plugged.
• The ray tracing versions of the indirectdiffuse() and occlusion() shadeops now work correctly with volumes.
• The use of Option "shutter" "int clampmotion" [0] and Shutter 0 0 no longer results in dropped geometry.
• Alpha channels derived from arbitrary opacity AOVs now correctly respect RiMatte.
• The handling of string arguments passed via -dspyargs to ptrender has been fixed.
• The VolumeField variable of the volume primitive is now automatically cached when baking for re-rendering.
• Fixed a bug that prevented RxTextureInfo from returning the correct code when using the "exists" query.
• The shader compiler now properly accounts for result detail and pre-promotion argument list detail when resolving overloaded function instances.
• RxOption and RxAttribute now properly check user options/attributes for arrays and set resultcount accordingly.
• The T43050 warning message can now be found and displayed.
• A Windows-only bug that could cause slpp to crash when compiling a shader has been addressed.
• Fixed a bug that could result in incorrect alpha for Matte 1 objects when using the subpixel hider.
• A bug in bake3d() that could cause NaNs and/or crash when using point-based indirectdiffuse() (et cetera) on geometry with detailed displacement and motion blur has been fixed.
• Fixed a bug that caused incorrect deep shadow map output when opacity is modified by visible point shading.
• Fixed a memory leak that could result from passing a nonexistent file to indirectdiffuse().

Changes in 16.1

Changes in 16.2

Changes in 16.3

Changes in 16.4

Changes in 16.5

Changes in 16.6

• Fixed a grid combining bug wherein the comparison of shader tags in structs had the inverted logic and would reject grids for combining erroneously.

Known Issues

• Using the raytrace hider with netrender currently only works with "bucket" screenorder and non-progressive rendering.
• Calling getshader(), getshaders(), getlight(), or getlights() during construct may result in unexpected behavior or sub-optimal performance.
• The evaluateSamplesEnv and generateSamplesEnv can only read latlong environment maps.

Deprecated

• The "vpvolumes" shading strategy has been deprecated, as visible point shaders now have first-class entrypoints, RiVPSurface, RiVPInterior, and RiVPAtmosphere, that do not require setting any other attribute state.
• The "specularthreshold" option has been deprecated. When appearing in legacy RIB files, the option is ignored.

Addenda

• There is a new version of the Pixar License Server, License Server 8.0. This new license server is not required, but does provide Network Address Translation support for sites that may need it.
• The Alfserver executable is no longer included with the RPS distribution, pursuant to the implementation of Tractor. Users are encouraged to migrate to the new distribution service, but may also avail themselves of Alfserver via the separate Alfred bundle, or may continue to use the version of Alfserver distributed with RPS 15.1.