shapeSet Element Reference

Groups a set of related shapes together within a common spatial acceleration data structure. More...

Inheritance diagram for shapeSet:

List of all members.

Attributes
string	spatialAccel
	Acceleration data structure for accelerating ray-object intersection queries and visibility tests that are prominent in many rendering algorithms.
string	kdSplitPlaneType
	Split plane generation method.
string	kdSplitAxisType
	Split axis selection method.
unsigned int	kdMinPrimitives
	Minimum number of primitives s.t. a leaf cell will automatically be created (below this number, further subdivision either won't help or requires too much memory.
unsigned int	kdMaxDepth
	Maximum depth of tree.
unsigned int	kdNoThreads
	number of threads to spawn during tree construction
real_t	kdCostTraversal
	SAH relative cost of traversal.
real_t	kdEmptyBias
	SAH empty cell bias factor.

---

Detailed Description

Groups a set of related shapes together within a common spatial acceleration data structure.

Any shape defined as a child of this shapeSet will be implicitly added to its acceleration data structure.

Note:

ShapeSets should not contain any emitters since as of writing this, they will not be handled properly by Milton; that is, all emitters must lie within the top-level scene element and not within sub shapeSet elements.

shapeSet corresponds to the underlying Milton class 'ShapeSet.'

---

Attribute Documentation

string shapeSet::spatialAccel

Acceleration data structure for accelerating ray-object intersection queries and visibility tests that are prominent in many rendering algorithms.

Available spatialAccel variants include: naive (no acceleration) and kdTree (default)

Note:

spatialAccel corresponds to the underlying Milton class 'SpatialAccel.'

'naive' spatialAccel corresponds to linear traversal through all primitives when calculating the closest positive intersection between a ray and a set of primitives

type	string
optional	true
default	kdTree

string shapeSet::kdSplitPlaneType

Split plane generation method.

Available variants include: splitPlaneMiddle, splitPlaneMedian, and splitPlaneSAH.

Note:

A kd-Tree constructed with splitPlaneMiddle and splitAxisRoundRobin is equivalent to a standard octree, but for ray tracing purposes, the surface area heuristic (splitPlaneSAH, the default) is generally preferred for its ability to concentrate efforts in dense regions of the scene.

type	string
optional	true
default	splitPlaneSAH

string shapeSet::kdSplitAxisType

Split axis selection method.

Available variants include: splitAxisRoundRobin and splitAxisLongestExtent

Note:

If splitPlaneSAH is selected, kdSplitAxisType will be ignored, and the split axis at each node will be selected according to the minimum expected SAH cost (with a few optimization-oriented exceptions..)

type	string
optional	true
default	none

unsigned int shapeSet::kdMinPrimitives

Minimum number of primitives s.t. a leaf cell will automatically be created (below this number, further subdivision either won't help or requires too much memory.

type	unsigned integer
optional	true
default	3

unsigned int shapeSet::kdMaxDepth

Maximum depth of tree.

type	unsigned integer
optional	true
default	24

unsigned int shapeSet::kdNoThreads

number of threads to spawn during tree construction

Note:

TODO; currently single-threaded construction

type	unsigned integer
optional	true
default	1

real_t shapeSet::kdCostTraversal

SAH relative cost of traversal.

type	real scalar
optional	true
default	1

real_t shapeSet::kdEmptyBias

SAH empty cell bias factor.

type	real scalar
optional	true
default	0.9