ViewDog is a viewer for nurbs functions, polygonal geometry, and to some degree for iso surfaces of functions over a 3D domain (via marching cube). It also can be used as a graphical frontend for a number of interpolation and approximation algorithms. Import and export via the Alias Wavefront 3.0 OBJ file format is possible.

All of the interpolation and approximation algorithms are very fast, and appropriate for huge data sets, for example from laser scanners or photogrametry. Local bicubic interpolation and multi level bspline approximation have a time complexity which depends only linearily on the number of data points, and the global interpolation and approximation algorithms make use of the fact that the coefficient matrix of the least squares normal equation has a maximum semi bandwidth of p (with p beeing the degree of the function which shall be calculated), so that these equations can be solved efficiently with band matrix functions.