Z-values

A z-value stored for a given location represents an attribute other than that location’s horizontal position. For example, the longitude and latitude of a point can be stored respectively as an x and y coordinate. The elevation of that same point would be stored as its z-value.

The graphic below illustrates the basis of 3D modeling—defining the x, y, and z dimensions of an object or phenomena.

Each dot in the graphic is labeled with its z-value, which, in this case, represents elevation. The x and y values of the dots, which are not labeled, define their horizontal position.

In an elevation or terrain model, the z-value represents elevation; in other kinds of surface models it represents the density or quantity of a particular attribute. For example, the cells of a raster surface could hold z-values that represent precipitation levels.