vtkClipVolume

Section: Visualization Toolkit Graphics Classes

Usage

vtkClipVolume is a filter that clips volume data (i.e., vtkImageData) using either: any subclass of vtkImplicitFunction or the input scalar data. The clipping operation cuts through the cells of the dataset--converting 3D image data into a 3D unstructured grid--returning everything inside of the specified implicit function (or greater than the scalar value). During the clipping the filter will produce pieces of a cell. (Compare this with vtkExtractGeometry or vtkGeometryFilter, which produces entire, uncut cells.) The output of this filter is a 3D unstructured grid (e.g., tetrahedra or other 3D cell types).

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.

The filter will produce an unstructured grid of entirely tetrahedra or a mixed grid of tetrahedra and other 3D cell types (e.g., wedges). Control this behavior by setting the Mixed3DCellGeneration. By default the Mixed3DCellGeneration is on and a combination of cell types will be produced. Note that producing mixed cell types is a faster than producing only tetrahedra.

To create an instance of class vtkClipVolume, simply invoke its constructor as follows

  obj = vtkClipVolume

Methods

The class vtkClipVolume has several methods that can be used. They are listed below. Note that the documentation is translated automatically from the VTK sources, and may not be completely intelligible. When in doubt, consult the VTK website. In the methods listed below, obj is an instance of the vtkClipVolume class.