Contributor - VTK rendering

Octaviz can be a good starting point. Octaviz is a VTK toolbox for octave.

You can also find a good starting point on matlabcentral. It's an example of mex interface for one VTK function with one simple example.

A wiki on the vtk website as an entry on how to implement an interface under Matlab.

A maybe more complete article on mex interfacing can be found on the kitware website.