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What's new in Version 2.4


SItoA version 2.4 is based on version of the Arnold core.

New features include:

• Ray traced BSSRDFs: A new alternative to point-cloud subsurface scattering has been added. This method is brute-force ray-tracing based, but produces visually identical results to the pointcloud technique. This approach removes a number of shortcomings of the pointcloud method, trading them for unbiased noise instead. The new method consumes zero extra memory, supports motion blur, supports interactive relighting, is fully multi-threaded, starts up immediately and does not degrade in performance as the scattering radius shrinks. For backwards compatibility this is provided as an option, with point clouds being the default setting. To use ray traced subsurface scattering, check the Raytraced option from the Sampling controls dialog.

• Mesh light: There is a new type of light available called mesh_light which takes a polymesh as a parameter and emits light using the polymesh's surface geometry. Read the mesh light topic for more details.

• A number of other improvements in the Arnold core are of interest:

• Improved sampling at secondary bounces: The 2D sampling patterns generated by Arnold will now be stratified even for secondary bounces instead of reverting to fully random sampling as before. This can greatly reduce the amount of noise, particularly when rendering things that are seen through near-specular effects like glossy reflections or refractions

• Improved sampling for SSS Point cloud: When baking diffuse lighting calculations into the SSS pointcloud, Arnold now uses MIS (multiple importance sampling) to reduce noise from large nearby area lights and the skydome. This may increase the number of rays slightly, but give higher quality sampling in those cases

• Improved smoothed normals: The quality of the smooth shading normals stored per-vertex in triangular tessellations has been improved by adjusting the weights used to average the triangle normals around a vertex. In addition to triangle area, the weights now factor the angle between the two triangle edges containing the shared vertex. This will be most evident for coarse meshes where the face normal and the smoothed vertex normals substantially differ.



We have finally removed support for Softimage 2010 in this release.


Version 2.3

SItoA version 2.3 is based on version of the Arnold core.

Highlighted new features:

• A new property, Arnold User Options, has been added. This is a general purpose property, consisting of a string, and flag to 'mute' (ignore) the property. If enabled, the string can be set to override any attribute of a core Arnold node. This can be useful for accessing new features in newer Arnold core releases even before they are fully supported natively in the SItoA UI. The property can be applied poly-meshes, hair, lights, cameras and point clouds.

• New spherical camera which helps to create lat-long environment maps more easily.

• Support for oriented curves for ICE strands. If no instance shape is in place, you can tell the curves primitive to orient the ribbons along the strand orientation directions. To do so, apply an Arnold Property to the pointcloud, and set the Curves Mode to Oriented Ribbon (ICE Strands).

• Export standins with all their materials and displacement for Exocortex Alembic. The Exocortex website has more details about Alembic for Arnold.

• The Stanford Polygonal format (.ply) has been added to the supported file extensions of standins (.ply support was added to Arnold core in 4.0.6).

• Added an ID mode to the utility shader to visualize a different color for each object which, unlike the obj mode which is based on the object name string, is guaranteed to not change through an animation.


New commands:

The following new commands have been added:

• SITOA_ExportObjects

• SITOA_AddUserOptionsProperties


See the SItoA Commands section for details.


Migration Issues:

Note that the SITOA_ExportScene command now no longer has a parameter toRender, this has been removed.


Version 2.2

Based on version of the Arnold core.

Highlighted new features:

• Softimage 2013 support.
• Preview standin in the viewport. See the SItoA Viewer section for details.

• Per-face displacement support (previously we only supported one displacement shader tree per object).
• Custom procedurals can be driven by data from ICE. See details here.

• Support for ICE materials system in Softimage 2012 and later.
• Custom user parameters on standins/procedural. See details here.

• Several new shaders ported (txt3d-marbletxt3d_checkerboard).
• Gamma Workflow in the sib_image_clip shader. Check the notes at ticket#506 comment:28.


Incompatible changes:

Because displacement is now handled per-face, some of the parameters that previously were assigned in the material level (in sta_displacement) have been moved to the Arnold Parameters PPG, per object. This has the effect that displacement parameters from older scenes will break and have to be reapplied individually.


Version 2.1

Based on version of the Arnold core.

Highlighted new features:

• SSS Skin Shader added. 

• *_Passthrough shaders added. 

• Color Lookup map shader with texture map support added. 

• ICE attributes on instanced lights. See Implementation details. 

• Ability to embed a DataWindow when saving EXR files. It stores a tight bounding box around non-empty pixels in the image, which can greatly accelerate compositing operations in Nuke as it will bebe interpreted in as a ROI (Region Of Interest). 

• Subframe deformation blur on ICE point clouds.


Incompatible changes:

Displacement Height no longer affects the displaced mesh's bounding box (i.e. the displacement "padding"). Now it only sets the scale for displacement. Displacement Padding must be set separately. If Displacement Padding is not set, you may get clipping artifacts in meshes with big displacements.


Version 2.0

Version 2.0 of SItoA is based on version 4.0.1 of the Arnold core, and as such includes a number of important changes.



As the first version digit of the Arnold core changed, your license will need to be upgraded to remove the watermark. Contact us to obtain a new license file using the "licensing@..." email address.


Significant new features include:

• Transparency support for AOV. It is now possible to automatically compose through semi-opaque surfaces rendered using auto-transparency. You can enable this option (turned off by default because there is an associated performance hit in the Arnold core which will be improved for future releases) in the output tab of the renderer settings.

• The Hair shader now exposes direct_diffusedirect_specular and indirect_diffuse AOVs.

• ICE attributes on polymesh objects. Constant, per polygon and varying data are supported. It works only with Softimage 2012 and newer. The supported attribute types are: booleanintegerfloatvector3 and rgba. Instance, 2d vectors etc. are not exported.

• Implemented the new handle based texture lookups in the image shader node. This can give around 1.2 times speedups in texture/autobump heavy scenes and in simple scenes with very long filenames the speedup was closer to 2 times.

• Smooth tangents for subdivision surfaces option. This feature only works with subdivided objects and allows to have Ward anisotropy with a non-faceted look (the object needs UV).


Incompatible changes:

There are some incompatible changes introduced with Arnold This will make older scenes to render different than in previous versions.

• Now lights have a decay control, which has been removed from the Light Decay filter. By default lights use a physically correct quadratic decay and linear and cubic light decay types have been removed.

• Decay clamp and Decay radius have therefore been removed from the Light Decay filter.

• The default value of the specular_roughness parameter in the Standard shader has changed from 0.467138 to 0.466905


• Remember that now the shaders and the procedurals search path obey rules specified on the wiki here.

• In this version, only AOVs of type RGB support transparency.

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