Core API

The Visualization Toolkit (VTK), developed by Kitware, has many mesh data types that PyVista wraps. This chapter is intended to describe these different mesh types and how we wrap and implement each of those mesh types in VTK. This chapter also highlights how all PyVista types have direct access to common VTK filters (see Filters).

All PyVista meshes inherit from the Common dataset type (see Datasets). PyVista has the following mesh types:

  • pyvista.PolyData consists of any 1D or 2D geometries to construct vertices, lines, polygons, and triangles. We generally use PolyData to construct scattered points and closed/open surfaces (non-volumetric datasets). The pyvista.PolyData class is an extension of vtk.vtkPolyData.

  • An pyvista.UnstructuredGrid is the most general dataset type that can hold any 1D, 2D, or 3D cell geometries. You can think of this as a 3D extension of PolyData that allows volumetric cells to be present. It’s fairly uncommon to explicitly make unstructured grids but they are often the result of different processing routines that might extract subsets of larger datasets. The pyvista.UnstructuredGrid class is an extension of vtk.UnstructuredGrid.

  • A pyvista.StructuredGrid is a regular lattice of points aligned with an internal coordinate axes such that the connectivity can be defined by a grid ordering. These are commonly made from np.meshgrid(). The cell types of structured grids must be 2D Quads or 3D Hexahedrons. The pyvista.StructuredGrid class is an extension of vtk.vtkStructuredGrid.

  • A pyvista.RectilinearGrid defines meshes with implicit geometries along the axes directions that are rectangular and regular. The pyvista.RectilinearGrid class is an extension of vtk.vtkRectilinearGrid.

  • Image data, commonly referenced to as uniform grids, and defined by the pyvista.UniformGrid class are meshes with implicit geometries where cell sizes are uniformly assigned along each axis and the spatial reference is built out from an origin point. The pyvista.UniformGrid class is an extension of vtk.vtkImageData.

  • pyvista.MultiBlock datasets are containers to hold several VTK datasets in one accessible and spatially referenced object. The pyvista.MultiBlock class is an extension of vtk.vtkMultiBlockDataSet.