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vtkHyperTree Class Referenceabstract

An object structured as a tree where each node has exactly either 2^n or 3^n children. More...

#include <vtkHyperTree.h>

Inherits vtkObject.

Public Types

typedef vtkObject Superclass
 

Public Member Functions

virtual int IsA (const char *type)
 
vtkHyperTreeNewInstance () const
 
virtual void Initialize ()=0
 
virtual vtkHyperTreeCursorNewCursor ()=0
 
virtual vtkIdType GetNumberOfLeaves ()=0
 
virtual vtkIdType GetNumberOfNodes ()=0
 
virtual vtkIdType GetNumberOfIndex ()=0
 
virtual int GetBranchFactor ()=0
 
virtual int GetDimension ()=0
 
virtual void SetScale (double[3])=0
 
virtual void GetScale (double[3])=0
 
virtual double GetScale (unsigned int)=0
 
virtual vtkIdType GetNumberOfLevels ()=0
 
virtual void SubdivideLeaf (vtkHyperTreeCursor *leaf)=0
 
virtual unsigned int GetActualMemorySize ()=0
 
virtual void FindChildParameters (int, vtkIdType &, bool &)
 
virtual void SetGlobalIndexStart (vtkIdType)=0
 
virtual void SetGlobalIndexFromLocal (vtkIdType local, vtkIdType global)=0
 
virtual vtkIdType GetGlobalIndexFromLocal (vtkIdType local)=0
 

Static Public Member Functions

static int IsTypeOf (const char *type)
 
static vtkHyperTreeSafeDownCast (vtkObjectBase *o)
 
static vtkHyperTreeCreateInstance (unsigned int branchFactor, unsigned int dimension)
 

Protected Member Functions

virtual vtkObjectBase * NewInstanceInternal () const
 
 vtkHyperTree ()
 

Detailed Description

An object structured as a tree where each node has exactly either 2^n or 3^n children.

An hypertree is a dataset where each node has either exactly 2^n or 3^n children or no child at all if the node is a leaf. `n' is the dimension of the dataset (1 (binary tree), 2 (quadtree) or 3 (octree) ). The class name comes from the following paper:

@ARTICLE{yau-srihari-1983,
 author={Mann-May Yau and Sargur N. Srihari},
 title={A Hierarchical Data Structure for Multidimensional Digital Images},
 journal={Communications of the ACM},
 month={July},
 year={1983},
 volume={26},
 number={7},
 pages={504--515}
 }

Each node is a cell. Attributes are associated with cells, not with points. The geometry is implicitly given by the size of the root node on each axis and position of the center and the orientation. (TODO: review center position and orientation). The geometry is then not limited to an hybercube but can have a rectangular shape. Attributes are associated with leaves. For LOD (Level-Of-Detail) purpose, attributes can be computed on none-leaf nodes by computing the average values from its children (which can be leaves or not).

By construction, an hypertree is efficient in memory usage when the geometry is sparse. The LOD feature allows to cull quickly part of the dataset.

This is an abstract class used as a superclass by a templated compact class. All methods are pure virtual. This is done to hide templates.

Case with 2^n children:
3D case (octree) for each node, each child index (from 0 to 7) is encoded in the following orientation. It is easy to access each child as a cell of a grid. Note also that the binary representation is relevant, each bit code a side: bit 0 encodes -x side (0) or +x side (1) bit 1 encodes -y side (0) or +y side (1) bit 2 encodes -z side (0) or +z side (2)
  • the -z side first
  • 0: -y -x sides
  • 1: -y +x sides
  • 2: +y -x sides
  • 3: +y +x sides
                 +y
    +-+-+        ^
    |2|3|        |
    +-+-+  O +z  +-> +x
    |0|1|
    +-+-+
    
Case with 2^n children:
  • then the +z side, in counter-clockwise
  • 4: -y -x sides
  • 5: -y +x sides
  • 6: +y -x sides
  • 7: +y +x sides
                 +y
    +-+-+        ^
    |6|7|        |
    +-+-+  O +z  +-> +x
    |4|5|
    +-+-+
    
Case with 2^n children:
The cases with fewer dimensions are consistent with the octree case:
Case with 2^n children:
Quadtree: in counter-clockwise
  • 0: -y -x edges
  • 1: -y +x edges
  • 2: +y -x edges
  • 3: +y +x edges
            +y
    +-+-+   ^
    |2|3|   |
    +-+-+  O+-> +x
    |0|1|
    +-+-+
    
Case with 2^n children:
Binary tree:
+0+1+  O+-> +x
Warning
It is not a spatial search object. If you are looking for this kind of octree see vtkCellLocator instead.
Thanks:
This class was written by Philippe Pebay, Joachim Pouderoux and Charles Law, Kitware 2013 This work was supported in part by Commissariat a l'Energie Atomique (CEA/DIF)

Definition at line 133 of file vtkHyperTree.h.

Member Typedef Documentation

typedef vtkObject vtkHyperTree::Superclass

Definition at line 136 of file vtkHyperTree.h.

Constructor & Destructor Documentation

vtkHyperTree::vtkHyperTree ( )
inlineprotected

Definition at line 184 of file vtkHyperTree.h.

Member Function Documentation

static int vtkHyperTree::IsTypeOf ( const char *  type)
static
virtual int vtkHyperTree::IsA ( const char *  type)
virtual
static vtkHyperTree* vtkHyperTree::SafeDownCast ( vtkObjectBase *  o)
static
virtual vtkObjectBase* vtkHyperTree::NewInstanceInternal ( ) const
protectedvirtual
vtkHyperTree* vtkHyperTree::NewInstance ( ) const
virtual void vtkHyperTree::Initialize ( )
pure virtual
virtual vtkHyperTreeCursor* vtkHyperTree::NewCursor ( )
pure virtual
virtual vtkIdType vtkHyperTree::GetNumberOfLeaves ( )
pure virtual
virtual vtkIdType vtkHyperTree::GetNumberOfNodes ( )
pure virtual
virtual vtkIdType vtkHyperTree::GetNumberOfIndex ( )
pure virtual
virtual int vtkHyperTree::GetBranchFactor ( )
pure virtual
virtual int vtkHyperTree::GetDimension ( )
pure virtual
virtual void vtkHyperTree::SetScale ( double  [3])
pure virtual
virtual void vtkHyperTree::GetScale ( double  [3])
pure virtual
virtual double vtkHyperTree::GetScale ( unsigned  int)
pure virtual
virtual vtkIdType vtkHyperTree::GetNumberOfLevels ( )
pure virtual

Return the number of levels.

Postcondition
result_greater_or_equal_to_one: result>=1
virtual void vtkHyperTree::SubdivideLeaf ( vtkHyperTreeCursor leaf)
pure virtual

Subdivide node pointed by cursor, only if its a leaf. At the end, cursor points on the node that used to be leaf.

Precondition
leaf_exists: leaf!=0
is_a_leaf: leaf->CurrentIsLeaf()
virtual unsigned int vtkHyperTree::GetActualMemorySize ( )
pure virtual

Return the actual memory size in kilobytes. NB: Ignores the attribute array.

static vtkHyperTree* vtkHyperTree::CreateInstance ( unsigned int  branchFactor,
unsigned int  dimension 
)
static

Return an instance of a templated hypertree for given branch factor and dimension This is done to hide templates.

virtual void vtkHyperTree::FindChildParameters ( int  ,
vtkIdType &  ,
bool &   
)
virtual

Find the Index, Parent Index and IsLeaf() parameters of a child for hypertree. This is done to hide templates.

virtual void vtkHyperTree::SetGlobalIndexStart ( vtkIdType  )
pure virtual

Set the start global index for the current tree. The global index of a node will be this index + the node index.

virtual void vtkHyperTree::SetGlobalIndexFromLocal ( vtkIdType  local,
vtkIdType  global 
)
pure virtual

Set the mapping between local & global ids used by HyperTreeGrids.

virtual vtkIdType vtkHyperTree::GetGlobalIndexFromLocal ( vtkIdType  local)
pure virtual

Get the global id of a local node. Use the mapping function if available or the start global index.


The documentation for this class was generated from the following file: