[GRASS-dev] anyone interested in helping to port an algorithm from matlab?

[Dylan Beaudette]

Hi,

I was taking another look on a paper published in Computers and GeoSciences on 
something called a 'Variance Quadtree' algorithm[1]. The main idea is to 
recursively partition an image into smaller and smaller rectangles, based on 
the amount of variance within each rectangle. Thus, regions of more variation 
get split into smaller nested rectangles. 

The source code for the algorithm is given in Matlab source[2]. I have tried 
unsuccessfully to port the code to R, mostly because I do not completely 
understand several of the matlab matrix idioms used in the code.

I think that a C version of the algorithm, along with some minor modifications 
to convert the quadtree structure into GRASS vectors (similar to what 
v.surf.rst can output) would be a nice addition to imagery analysis in GRASS.

Anyone want to give some pointers / help on porting this to C? The algorithm 
is relatively simple, however some of the matlab-specific matrix operations 
may be a challenge.

1. http://dx.doi.org/10.1016/j.cageo.2006.08.009
2. http://www.usyd.edu.au/su/agric/acpa/software/matlab/vqt_matlab.zip


Cheers,

Dylan

-- 
Dylan Beaudette
Soil Resource Laboratory
http://casoilresource.lawr.ucdavis.edu/
University of California at Davis
530.754.7341