Measure Volume and Area reports total surface areas and surface-enclosed volumes. Surfaces handled are:
The related tool Area/Volume from Web uses the StrucTools server to calculate surface areas and Voronoi volumes from molecular coordinates and assigns the per-atom values as atom attributes (see the summary of differences).
There are several ways to start Measure Volume and Area, a tool in the Surface/Binding Analysis and Volume Data categories.
The surface of interest should be chosen from the Surface menu. Clicking Compute Volume and Area performs the measurements. Values are reported in the dialog and written to the the Reply Log. The results are reported in the physical units of the data, usually Å3 for volume and Å2 for area.
The surface area and surface-enclosed volume depend on the positions and spacing of vertices in the surface, and will change if (for example) the probe radius or vertex density attribute of a molecular surface is changed, or if an isosurface shown with Volume Viewer or Multiscale Models is smoothed.
Clipping and hiding are ignored. The volume calculation uses the full surface, even if part of it is hidden by clipping planes or zoning (with Surface Zone or zoning in Volume Viewer).
Surface holes. If the surface has holes, the volume will not be computed because it is not known what is inside and what is outside the surface. Molecular surfaces and surfaces from Multiscale Models should never have holes. A contour surface from Volume Viewer will only have holes if it reaches the boundary of the volume data set. Several methods can eliminate such holes:
Multiple enclosed volumes. If a surface encloses disjoint regions of space, the total volume of all regions will be reported. There is no way to select a particular enclosure to calculate its volume. For contour surfaces from Volume Viewer, subregion selection or Volume Eraser can be used to limit the calculation to the region of interest.