Documentation for vtkScalarTree

vtkScalarTree - organize data according to scalar values (used to accelerate contouring operations)

Description:

vtkScalarTree creates a pointerless binary tree that helps search for cells that lie within a particular scalar range. This object is used to accelerate some contouring (and other scalar-baed techniques). The tree consists of an array of (min,max) scalar range pairs per node in the tree. The (min,max) range is determined from looking at the range of the children of the tree node. If the node is a leaf, then the range is determined by scanning the range of scalar data in n cells in the dataset. The n cells are determined by arbitrary selecting cell ids from id(i) to id(i+n), and where n is specified using the BranchingFactor ivar. Note that leaf node i=0 contains the scalar range computed from cell ids (0,n-1); leaf node i=1 contains the range from cell ids (n,2n-1); and so on. The implication is that there are no direct lists of cell ids per leaf node, instead the cell ids are implicitly known.

Methods:

	void vtkScalarTree ()
	void vtkScalarTree ()
	const char *GetClassName ()
	void PrintSelf (unknown & ,vtkIndent )
	static vtkScalarTree *New ()
	void SetDataSet (vtkDataSet *)
	vtkDataSet *GetDataSet ()
	void SetBranchingFactor (int )
	int GetBranchingFactor ()
	int GetLevel ()
	void SetMaxLevel (int )
	int GetMaxLevel ()
	void BuildTree ()
	void Initialize ()
	void InitTraversal (float )
	vtkCell GetNextCell (int & ,vtkIdList ,vtkScalars )
	vtkCell *GetNextCell (int & ,vtkIdList ,vtkScalars &)
	int FindStartLeaf (int ,int )
	int FindNextLeaf (int ,int )

Detailed Method Descriptions:

Instantiate scalar tree with maximum level of 20 and branching factor of 5.

static vtkScalarTree *New ()

Build the tree from the points/cells defining this dataset.

	void SetDataSet (vtkDataSet *)
	vtkDataSet *GetDataSet ()

Set the branching factor for the tree. This is the number of children per tree node. Smaller values (minimum is 2) mean deeper trees and more memory overhead. Larger values mean shallower trees, less memory usage, but worse performance.

	void SetBranchingFactor (int )
	int GetBranchingFactor ()

Get the level of the locator (determined automatically if Automatic is true). The value of this ivar may change each time the locator is built.

int GetLevel ()

Set the maximum allowable level for the tree.

	void SetMaxLevel (int )
	int GetMaxLevel ()

Construct the scalar tree from the dataset provided. Checks build times and modified time from input and reconstructs the tree if necessaery.

void BuildTree ()

Initialize locator. Frees memory and resets object as appropriate.

void Initialize ()

Begin to traverse the cells based on a scalar value. Returned cells will have scalar values that span the scalar value specified.

void InitTraversal (float )

Return the next cell that may contain scalar value specified to initialize traversal. The value NULL is returned if the list is exhausted. Make sure that InitTraversal() has been invoked first or you'll get erratic behavior.

vtkCell *GetNextCell (int & ,vtkIdList ,vtkScalars *)