Hello, I found the Line Integral Convolution (LIC) example very timely for a project I'm working on. http://www.scipy.org/Cookbook/LineIntegralConvolution Once Cython & Pyrex were installed, the demo ran out of the box. Excellent. However, now I'm trying to apply this to a different dataset and the C component is crashing with index errors. I suspect these are being caused by the fact that my dataset is not a square array. An examination in the .pyx file has a couple of locations where the array indices appear to be transposed between x,y vs i,j. I'm not sure if this is a bug or not. The high symmetry of the demo vector field would probably not reveal this if it were a bug. So my questions for the author of the code or the list are: 1) Is there a paper or other reference for the algorithm implemented here? My searches have revealed several types of LIC implementations. It would be nice if this were in code comments or at least on the tutorial page. 2) Is the algorithm, the demo code, or LIC in general, restricted to square arrays? 3) Is there a pure-python or numpy-only (no Cython or Pyrex requirement) implementation? Thanks, Tom -- Dr. William T."Tom" Bridgman Scientific Visualization Studio Global Science & Technology, Inc. NASA/Goddard Space Flight Center Email: William.T.Bridgman@nasa.gov Code 610.3 Phone: 301-286-1346 Greenbelt, MD 20771 FAX: 301-286-1634 http://svs.gsfc.nasa.gov/