Krakatoa SR Beta - Feature List

Deprecated Krakatoa SR Beta Documentation
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[size=200]Krakatoa SR Beta - Feature List[/size]

Document Started: 2011/10/10
Document Edited: 2012/12/05
WORK IN PROGRESS

[size=150]Particle Sources[/size]
Krakatoa SR currently accepts the following particle sources:

  • Krakatoa PRT files, saved from any application that supports writing to PRT (incl. 3ds Max, Maya, Softimage, Houdini, Naiad, RealFlow 2012).
  • RealFlow Particle BIN files, saved from RealFlow or any application supporting saving to BIN
  • ASCII Comma-separated values CSV files, saved from any application that supports writing text files
  • OBJ Geometry files as volume to be filled with particles at render time
  • Spline files (currently based on PRT specs) for converting curves to particles at render tine with Hair rendering options and density falloff.
  • Fractal-generated particles based on random seeds or user transformations.

[size=150]Particle Channel Sources[/size]
Krakatoa SR supports setting or scaling the incoming channels of a PRT files, such as “Color”, “Emission”, or “Density”. The 3D application exporting the PRT data can provide arbitrary channel data per particle using the source application’s shading system.

[size=150]Phase Functions[/size]
Krakatoa SR currently implements the same hard-coded phase functions (shading modes) available in Krakatoa MX:

  • Isotropic - light is scattered equally in all directions
  • Phong Surface - light is scattered by each particle according to its Normal channel which is taken from the X axis of the particle’s transformation, as well as the light and viewing directions.
  • Henyey-Greenstein - light is scattered according to the angle between the light and viewing directions with a Phase Eccentricity parameter controlling the effect. A Phase Eccentricity of 0.0 produces Isotropic scattering.
  • Schlick - light is scattered according to the angle between the light and viewing directions with a Phase Eccentricity parameter controlling the effect. A Phase Eccentricity of 0.0 produces Isotropic scattering.
  • Kajiya-Kay - a simple Hair shading model with just one specular highlight set of controls.
  • Marschner - an advanced Hair shading model with secondary highlights, glint controls and more.

In the current implementation of both Krakatoa MX and SR, these phase functions are built in. In future implementations, they might be separated to external plugins with an API for developing new light scattering models.

[size=150]Motion Blur[/size]
Krakatoa SR supports temporal blurring of particles and matte objects taking into account the velocity of particles, transformation changes of camera and objects and changing geometry using multiple geometry samples.

  • The Velocity channel of the particle is used to draw multiple samples along the motion vector. Note that the lighting is currently performed just once in the center of the shutter interval. An option to force relighting on each sub-sample is on the Wishlist.
  • A Jittered Motion Blur option allows the randomization of the sample’s position along the velocity vector to produce a more natural look without obvious strobbing.
  • The transformation matrix of the camera can be exported on multiple sub-frames to produce camera motion blur.
  • The transformation matrix of each particle source can be exported on multiple sub-frames to produce object motion blur.
  • The transformation matrix of each matte object can be exported on multiple sub-frames to produce matte object motion blur.
  • The geometry of each matte object can be exported on multiple sub-frames to produce deformation motion blur. The topology of the matte geometry must be consistent between samples!

The Motion Blur controls include

  • Shutter Angle in degrees, default is 180.0
  • Particle Segments defining the number of particle samples to draw, default is 2. Using 1 produces no Motion Blur. Using 1 with Jitter on can be used to randomize the positions of the particles in a single image sample.
  • Bias - defines the offset from the centered shutter interval. In both Krakatoa SR 2 and Krakatoa MX 2, this affects both particles and matte objects. In older Krakatoa MX versions, it used to affect only the matte objects bias.

[size=150]Depth Of Field[/size]
Krakatoa SR implements Depth Of Field by drawing multiple samples of each particle within the circle of confusion calculated using the focal distance, f-stop and focal length in system units provided for the camera.
A Depth Of Field Sample Rate controls the quantity of samples to be drawn per particle, default is 0.1.

[size=150]Matte Objects[/size]
Krakatoa SR currently implements Matte Objects using OBJ geometry files. The Geometry is rasterized internally into a Depth Map used to determine whether a particle is in front or behind geometry. The Depth Map can be rendered at higher resolutions to allow for super-sampling (multiple depth map pixels per particle).
Krakatoa MX also supports “Initial Depth Maps” which can be used to initialize the depth buffer using external depth map sources, for example depth maps for other renderers. This is useful to support render-time displacement. This option is not implemented in Krakatoa SR Beta yet.
The Krakatoa SR Wishlist currently includes the support for Deep Shadow Maps and Deep Compositing as the ultimate goal for future matte and shadow casting workflows.

[size=150]Deep Image Importing[/size]
As an alternative to matte objects, users can import deep images from 3rd party geometry renderers to be used as shadow maps and holdout masks. Currently only RenderMan DTEX and 3Delight DSM formats are supported. To load a deep image, a 3rd party loading library must be provided (for example, RenderMan’s libprman.dll).