[SciPy-user] Questions about Line Integral Convolution tutorial

Bridgman, William T. William.T.Bridgman@nasa....
Mon Nov 24 10:46:00 CST 2008


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/






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