MATLAB Central - File detail - Surface Curvature
Here is an example of using matlab to plot 4D data. The Fourth dimension (in colour) is the curvature of the surface at that partcular (x,y,z) point. Hope this helps.
This is done using MATLAB's "surf" function.
EDU>> help surf
SURF 3-D colored surface.
SURF(X,Y,Z,C) plots the colored parametric surface defined by
four matrix arguments. The view point is specified by VIEW.
The axis labels are determined by the range of X, Y and Z,
or by the current setting of AXIS. The color scaling is determined
by the range of C, or by the current setting of CAXIS. The scaled
color values are used as indices into the current COLORMAP.
The shading model is set by SHADING.