photonMapper Element Reference

Implementation of Henrik Wann Jensen's photon mapping algorithm. More...

Inheritance diagram for photonMapper:

List of all members.

Attributes
unsigned int	noRenderThreads
	Number of core rendering threads to use during rendering.
unsigned int	noDirectSamples
	Number of direct "shadow rays" to sample from area light sources during evaluation of direct illumination.
generator	directSampleGenerator
generator	generator
	generator to use to generate samples over the film plane
unsigned int	diffuseNoGatherPhotons
	Maximum number of diffuse photons to be gathered during KNN for irradiance estimates from the diffuse photon map.
unsigned int	causticNoGatherPhotons
	Maximum number of caustic photons to be gathered during KNN for irradiance estimates from the caustic photon map.
ureal_t	diffuseGatherRadius
	Maximum KNN search radius during irradiance estimates from the diffuse photon map.
ureal_t	causticGatherRadius
	Maximum KNN search radius during irradiance estimates from the caustic photon map.
unsigned int	diffuseNoPhotons
	Maximum number of (diffuse photons to shoot from emitters) and (photons to store in the diffuse photon map).
unsigned int	causticNoPhotons
	Maximum number of (caustic photons to shoot from emitters) and (photons to store in the caustic photon map).

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Detailed Description

Implementation of Henrik Wann Jensen's photon mapping algorithm.

Photon Mapping is a two-pass global illumination algorithm in which photons are first traced from light sources and stored in a global kd-tree called the photon map. Final gathering is then performed by tracing paths from the eye and using photons from the photon map to approximate irradiance at points.

Note:

Photon mapping parameters are generally especially scene-dependent.,Photon mapping treats diffuse and caustic paths separately, so many photonMapper-specific parameters have separate diffuse and caustic versions.,Photon mapping is a consistent estimator of Kajiya's rendering equation, in that its expected value converges to the true value only in the limit as the number of samples -> infinity.,See Jensen's book, "Realistic Image Synthesis Using Photon Mapping" (2001) for further details.

photonMapper corresponds to the underlying Milton class 'PhotonMapper.'

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Attribute Documentation

unsigned int photonMapper::noRenderThreads

Number of core rendering threads to use during rendering.

Rendering in Milton is highly concurrent and is designed from the ground up to scale well with an increasing number of processors on the underlying machine. Choosing too few threads will drastically affect the performance of Milton by not taking advantage of all available resources. On the other hand, choosing too many threads may bottleneck the system and cause cache / memory thrashing from frequent time sharing between the threads across an insufficient number of available processors. A good rule of thumb is to choose noRenderThreads to be about 2 times the number of available processors. i.e., if you're on a quad-core machine, setting noRenderThreads to 8 or 10 will yield optional usage of the 4 available processors.

type	unsigned integer
optional	true
default	8

unsigned int photonMapper::noDirectSamples

Number of direct "shadow rays" to sample from area light sources during evaluation of direct illumination.

type	unsigned integer
optional	true
default	1

generator photonMapper::directSampleGenerator

type	generator
optional	true
default	jittered

generator photonMapper::generator

generator to use to generate samples over the film plane

type	generator
optional	true
default	super

unsigned int photonMapper::diffuseNoGatherPhotons

Maximum number of diffuse photons to be gathered during KNN for irradiance estimates from the diffuse photon map.

type	unsigned integer
optional	true
default	500

unsigned int photonMapper::causticNoGatherPhotons

Maximum number of caustic photons to be gathered during KNN for irradiance estimates from the caustic photon map.

Note:

Because caustics are by their very nature a focusing event, you can generally set causticNoGatherPhotons to be much lower than diffuseNoGatherPhotons without compromising the quality of your render.

type	unsigned integer
optional	true
default	300

ureal_t photonMapper::diffuseGatherRadius

Maximum KNN search radius during irradiance estimates from the diffuse photon map.

Note:

This parameter depends greatly on the scale of your scene.

type	positive real scalar
optional	true
default	1

ureal_t photonMapper::causticGatherRadius

Maximum KNN search radius during irradiance estimates from the caustic photon map.

Note:

This parameter depends greatly on the scale of your scene.

type	positive real scalar
optional	true
default	1

unsigned int photonMapper::diffuseNoPhotons

Maximum number of (diffuse photons to shoot from emitters) and (photons to store in the diffuse photon map).

type	unsigned integer
optional	true
default	60000

unsigned int photonMapper::causticNoPhotons

Maximum number of (caustic photons to shoot from emitters) and (photons to store in the caustic photon map).

type	unsigned integer
optional	true
default	60000