At ArcGIS Desktop 9.2, a new tool in ArcMap lets you perform calculations on the feature geometry in the attribute tables of feature layers. The Calculate Geometry tool calculates lengths; areas; and x,y coordinates. In previous releases, these operations were carried out by writing custom Visual Basic for Applications (VBA) code. Now these fields can be generated through a simple menu choice.
The geometry that can be calculated depends on the feature used. Polygon features have the most options: area, perimeter, x-coordinate of centroid, and y-coordinate of centroid. Point features have the fewest choices: x-coordinate of point and y-coordinate of point. The x-coordinate of centroid and y-coordinate of centroid can be calculated for line and annotation features. The length of line features can also be calculated.
These calculations take place in projected, rather than spherical or geodesic, space. For data sources in a geographic coordinate system, such as World Geodetic System (WGS) 1984 (i.e., unprojected), the projected coordinate system of the data frame can be used for calculations.
If the geometry for only a subset of the attribute table is required, create a selection of that subset before using Calculate Geometry and the tool will calculate values only for selected records.