Documentation for vtkClipVolume

vtkClipVolume - clip volume data with user-specified implicit function or input scalar data

Super Class: vtkStructuredPointsToUnstructuredGridFilter

Description:

vtkClipVolume is a filter that clips volume data (i.e., structured points) using either: any subclass of vtkImplicitFunction; or the input scalar data. Clipping means that it actually "cuts" through the cells of the dataset, returning everthing inside of the specified implicit function (or greater than the scalar value) including "pieces" of a cell. (Compare this with vtkExtractGeometry or vtkGeometryFilter, which pulls out entire, uncut cells.) The output of this filter is a 3D unstructured grid (e.g., tetrahedra). To use this filter, you must decide if you will be clipping with an implicit function, or whether you will be using the input scalar data. If you want to clip with an implicit function, you must first define and then set the implicit function with the SetClipFunction() method. Otherwise, you must make sure input scalar data is available. You can also specify a scalar value, which is used to decide what is inside and outside of the implicit function. You can also reverse the sense of what inside/outside is by setting the InsideOut instance variable. (The cutting algorithm proceeds by computing an implicit function value or using the input scalar data for each point in the dataset. This is compared to the scalar value to determine inside/outside.) This filter can be configured to compute a second output. The second output is the portion of the volume that is clipped away. Set the GenerateClippedData boolean on if you wish to access this output data.

 

Caveats:

This filter is designed to function with 3D structured points. Clipping 2D images can be better done by converting the image to polygonal data and using vtkClipPolyData,

 

See Also:

vtkImplicitFunction vtkClipPolyData vtkGeometryFilter vtkExtractGeometry

 

Methods:

void vtkClipVolume (vtkImplicitFunction *)
void vtkClipVolume ()
const char *GetClassName ()
void PrintSelf (unknown & ,vtkIndent )
static vtkClipVolume *New ()
void SetValue (float )
float GetValue ()
void SetInsideOut (int )
int GetInsideOut ()
void InsideOutOn ()
void InsideOutOff ()
void SetClipFunction (vtkImplicitFunction *)
vtkImplicitFunction *GetClipFunction ()
void SetGenerateClipScalars (int )
int GetGenerateClipScalars ()
void GenerateClipScalarsOn ()
void GenerateClipScalarsOff ()
void SetGenerateClippedOutput (int )
int GetGenerateClippedOutput ()
void GenerateClippedOutputOn ()
void GenerateClippedOutputOff ()
vtkUnstructuredGrid *GetClippedOutput ()
void SetMergeTolerance (float )
float GetMergeTolerance ()
void SetLocator (vtkPointLocator *)
vtkPointLocator *GetLocator ()
void CreateDefaultLocator ()
unsigned long GetMTime ()
void SetLocator (vtkPointLocator &)
void Execute ()
void ClipVoxel (float ,vtkScalars * ,int ,float ,float ,vtkIdList * ,vtkPoints * ,vtkPointData * ,vtkPointData * ,vtkCellData * ,int ,vtkCellData * ,vtkCellData *)

 

Detailed Method Descriptions:

Construct with user-specified implicit function; InsideOut turned off; value set to 0.0; and generate clip scalars turned off. The merge tolerance is set to 0.01.

static vtkClipVolume *New ()

Set the clipping value of the implicit function (if clipping with implicit function) or scalar value (if clipping with scalars). The default value is 0.0.

void SetValue (float )
float GetValue ()

Set/Get the InsideOut flag. When off, a vertex is considered inside the implicit function if its value is greater than the Value ivar. When InsideOutside is turned on, a vertex is considered inside the implicit function if its implicit function value is less than or equal to the Value ivar. InsideOut is off by default.

void SetInsideOut (int )
int GetInsideOut ()
void InsideOutOn ()
void InsideOutOff ()

If this flag is enabled, then the output scalar values will be interpolated from the implicit function values, and not the input scalar data. If you enable this flag but do not provide an implicit function an error will be reported.

void SetGenerateClipScalars (int )
int GetGenerateClipScalars ()
void GenerateClipScalarsOn ()
void GenerateClipScalarsOff ()

Control whether a second output is generated. The second output contains the unstructured grid that's been clipped away.

void SetGenerateClippedOutput (int )
int GetGenerateClippedOutput ()
void GenerateClippedOutputOn ()
void GenerateClippedOutputOff ()

Return the clipped output.

vtkUnstructuredGrid *GetClippedOutput ()

Set the tolerance for merging clip intersection points that are near the corners of voxels. This tolerance is used to prevent the generation of degenerate tetrahedra.

void SetMergeTolerance (float )
float GetMergeTolerance ()

Set / Get a spatial locator for merging points. By default, an instance of vtkMergePoints is used.

void SetLocator (vtkPointLocator *)
vtkPointLocator *GetLocator ()

Create default locator. Used to create one when none is specified. The locator is used to merge coincident points.

void CreateDefaultLocator ()

Return the mtime also considering the locator and clip function.

unsigned long GetMTime ()

For legacy compatibility. Do not use.

void SetLocator (vtkPointLocator &)