Module: Surface Area Volume ()

Description:

This module calculates the area of the individual patches of a surface (patch mode). The results are stored in a Spreadsheet data object.

In an alternative mode the area and the enclosed volume of the different regions defined in the surface are computed (material mode). In this mode the total surface area is twice as large since every triangle contributes to two regions. Note that for this mode it is required that the surface be closed, i.e., that all regions are completely enclosed by triangles. Otherwise, the computed volumes will be incorrect.

Actually, the volume computation simply sums the signed volumes of all of the tetrahedra joining surface triangles to the origin (point with coordinates x=0, y=0, z=0). The sign of the volumes depends on triangle orientation relative to the origin, so volumes are computed correctly even for non convex surfaces. In the case of a closed surface, the result is the volume of the enclosed surface. If the surface is not closed, then the result can be considered as the volume comprised between the surface (triangles) and the origin, which can be still useful depending on your purpose.

Press the Apply button to start the computation.

Connections:

Data [required]
The surface to be investigated.

Ports:

Mode

Toggles between material mode and patch mode.

In material mode the resulting spreadsheet object contains one row for every non-empty region of the surface. Each row contains the name of the region, the number of triangles of the region's boundary, the surface area of the boundary, as well as the enclosed volume. Usually, for the exterior region the volume is negative.

In patch mode the resulting spreadsheet object contains one row for every patch of the surface. Each row contains the patch id, the patch's inner region name, the patch's outer region name, the number of triangles of the patch, and the surface area of the patch. In the following columns the total number of triangles and the total surface area are printed. If the surface data structure also contains the surface contour, the surface perimeter is displayed. Note that you might have to use the recompute command of the Surface module, to obtain the contour information.