# VTK/Tutorials/3DDataTypes

- Here is a demonstration of how to use the structured data types : Demonstration of structured data types

# Structured Data

Structured data takes advantage of the knowledge of the connectivity of the points. It tries to store a representation of the points with out explicitly storing the coordinates of each point.

## Image Data

Points are arranged on a regular, rectangular lattice parallel to the global coordinate system. You only have to specify the origin ("bottom left corner") of the grid, and the spacing in each dimension. The grid is implicit, so you don't have to specify the coordinates of each point anywhere. You can define scalars or vectors at each point.

## Rectilinear Grid

This is a slight extension of Image Data. The points are still aligned along the coordinate axis, but the spacing between points may vary. The point coordinates are again implicit.

## Structured Grid

Regular topology and irregular geometry. That is, every point has a left, right, up, down, front, back neighbor. The points, however, do not lie on a grid! You must explicitly indicate the coordinates of each point.

This data structure is common in finite difference analysis.

# Unstructured Data

Unstructured data explicitly stores the coordinates of each point.

## Polygonal Data (PolyData)

Unstructured topology and geometry. Supports 0D (vertices), 1D (lines), and 2D (triangles, quads, general polygons) cells. You must explicitly indicate the coordinates of each point.

## Unstructured Grid

This is the most general form of data storage. Both topology and geometry are completely unstructured. Supports 0D (vertices) , 1D (lines) , 2D (triangles, quads, general polygons), and 3D (tetrahedra, other volumetric objects) cells. You must explicitly indicate the coordinates of each point.