2.7 SCIRun Objects

SCIRun's Field, Mesh, Matrix, and ColorMap objects are used frequently in networks. These objects are described in the following sections.

2.7.1 Field

A SCIRun Field consists of a geometric Mesh and a set of data values. Data values can be located at the nodes, edges, faces, or cells of a mesh. A Field can consist of a Mesh component only (no associated data).

2.7.2 Field Data

The following C++/SCI data types can be associated with a Field:

• double, float
• int, short, unsigned, unsigned short
• char, unsigned char
• 2nd order Tensor
• Vector of doubles

C++ data types are double, float, int, short, unsigned, unsigned short, char, and unsigned char. SCIRun data types are Tensor and Vector.

2.7.3 Meshes

SCIRun meshes are classified as unstructured, structured, or regular. A mesh consists of nodes and implicit or explicit node connectivity information.

Node locations and connectivities for unstructured meshes are specified explicitly. The unstructured mesh types are: PointCloudMesh, CurveMesh, TriSurfMesh, QuadSurfMesh, TetVolMesh, and HexVolMesh.

Node locations are specified explicitly, and connectivities are known implicitly for structured meshes. The structured meshes are StructCurveMesh, StructQuadSurfMesh, and StructHexVolMesh.

Node locations and connectivities are known implicitly for regular meshes. The regular mesh types are ScanlineMesh, ImageMesh, LatVolMesh.

A regular mesh is more constrained than structured and unstructured meshes. Likewise, a structured mesh is more constrained that a unstructured mesh. A more constrained mesh can be trivially converted to a less constrained mesh by explicitly enumerating implicit properties. For instance, a LatVol mesh is converted to a StructHexVol by enumerating a LatVol mesh's node coordinates (connectivities are still implied). Also, a LatVol mesh is converted to a HexVol mesh by enumerating a LatVol's node locations and connectivities. Module ToStructured performs this type of conversion.

It is not meaningful to convert a less constrained mesh to a more constrained mesh. It is possible, however, to sample an unstructured field at regular intervals to create a regular field. For example, a HexVolField is interpolated onto a LatVol mesh using modules SampleLattice and DirectInterpolate.

Below are figures of mesh types:

A Point Cloud mesh is a set of unconnected points.

A Scanline Mesh is a regularly segmented straight line (a regular 1D grid).

A Curve mesh is a segmented curve.

An Image mesh is a regular 2D grid. Note that an Image mesh is not used for image processing.

Surface made of connected quadrilaterals on a structured grid

Subdivision of space into structured hexagonal elements

A Tri Surface mesh is a surface made of connected triangles.

A Quad Surface mesh is a surface made of connected quadrilaterals.

A Lattice Volume mesh is a regular 3D grid.

A Tet Volume mesh is a subdivision of space into tetrahedral elements.

A Hex Volume mesh is a subdivision of space into hexagonal elements.

A Prism Volume mesh is a subdivision of space into prism elements. Prism elements have five faces, two trangular faces connected by three quadrilateral faces.

2.7.4 Matrices

SCIRun supports three matrix types:

ColumnMatrix

An Mx1 mathend000# matrix using M mathend000# storage units.

DenseMatrix

An MxN mathend000# matrix using MxN mathend000# storage units.

SparseRowMatrix

A MxN mathend000# matrix where most elements are zero and no storage is allocated for zero valued elements.

2.7.5 Color Map

SCIRun ColorMap type is a mapping of color values to data values.