Documentation for vtkImplicitModeller

vtkImplicitModeller - compute distance from input geometry on structured point dataset

Super Class: vtkDataSetToStructuredPointsFilter

Description:

vtkImplicitModeller is a filter that computes the distance from the input geometry to the points of an output structured point set. This distance function can then be "contoured" to generate new, offset surfaces from the original geometry. An important feature of this object is "capping". If capping is turned on, after the implicit model is created, the values on the boundary of the structured points dataset are set to the cap value. This is used to force closure of the resulting contoured surface. Note, however, that large cap values can generate weird surface normals in those cells adjacent to the boundary of the dataset. Using smaller cap value will reduce this effect. Another important ivar is MaximumDistance. This controls how far into the volume the distance function is computed from the input geometry. Small values give significant increases in performance. However, there can strange sampling effects at the extreme range of the MaximumDistance. In order to properly execute and sample the input data, a rectangular region in space must be defined (this is the ivar ModelBounds). If not explicitly defined, the model bounds will be computed. Note that to avoid boundary effects, it is possible to adjust the model bounds (i.e., using the AdjustBounds and AdjustDistance ivars) to strictly contain the sampled data. This filter has one other unusual capability: it is possible to append data in a sequence of operations to generate a single output. This is useful when you have multiple datasets and want to create a conglomeration of all the data.

 

See Also:

vtkSampleFunction vtkContourFilter

 

Methods:

void vtkImplicitModeller ()
const char *GetClassName ()
void PrintSelf (unknown & ,vtkIndent )
static vtkImplicitModeller *New ()
float ComputeModelBounds ()
int *GetSampleDimensions ()
void SetSampleDimensions (int ,int ,int )
void SetSampleDimensions (int )
void SetMaximumDistance (float )
float GetMaximumDistance ()
void SetModelBounds (float ,float ,float ,float ,float ,float )
void SetModelBounds (float *)
float *GetModelBounds ()
void SetAdjustBounds (int )
int GetAdjustBounds ()
void AdjustBoundsOn ()
void AdjustBoundsOff ()
void SetAdjustDistance (float )
float GetAdjustDistance ()
void SetCapping (int )
int GetCapping ()
void CappingOn ()
void CappingOff ()
void SetCapValue (float )
float GetCapValue ()
void Update ()
void StartAppend ()
void Append (vtkDataSet *)
void EndAppend ()
void Execute ()
void Cap (vtkScalars *)

 

Detailed Method Descriptions:

Construct with sample dimensions=(50,50,50), and so that model bounds are automatically computed from the input. Capping is turned on with CapValue equal to a large positive number.

static vtkImplicitModeller *New ()

Compute ModelBounds from input geometry.

float ComputeModelBounds ()

Set/Get the i-j-k dimensions on which to sample distance function.

int *GetSampleDimensions ()
void SetSampleDimensions (int ,int ,int )
void SetSampleDimensions (int )

Set / get the distance away from surface of input geometry to sample. Smaller values make large increases in performance.

void SetMaximumDistance (float )
float GetMaximumDistance ()

Set / get the region in space in which to perform the sampling. If not specified, it will be computed automatically.

void SetModelBounds (float ,float ,float ,float ,float ,float )
void SetModelBounds (float *)
float *GetModelBounds ()

Control how the model bounds are computed. If the ivar AdjustBounds is set, then the bounds specified (or computed automatically) is modified by the fraction given by AdjustDistance. This means that the model bounds is expanded in each of the x-y-z directions.

void SetAdjustBounds (int )
int GetAdjustBounds ()
void AdjustBoundsOn ()
void AdjustBoundsOff ()

Specify the amount to grow the model bounds (if the ivar AdjustBounds is set). The value is a fraction of the maximum length of the sides of the box specified by the model bounds.

void SetAdjustDistance (float )
float GetAdjustDistance ()

The outer boundary of the structured point set can be assigned a particular value. This can be used to close or "cap" all surfaces.

void SetCapping (int )
int GetCapping ()
void CappingOn ()
void CappingOff ()

Specify the capping value to use. The CapValue is also used as an initial distance value at each point in the dataset.

void SetCapValue (float )
float GetCapValue ()

Special update methods handles possibility of appending data.

void Update ()

Initialize the filter for appending data. You must invoke the StartAppend() method before doing successive Appends(). It's also a good idea to manually specify the model bounds; otherwise the input bounds for the data will be used.

void StartAppend ()

Append a data set to the existing output. To use this function, you'll have to invoke the StartAppend() method before doing successive appends. It's also a good idea to specify the model bounds; otherwise the input model bounds is used. When you've finished appending, use the EndAppend() method.

void Append (vtkDataSet *)

Method completes the append process.

void EndAppend ()