[GRASS-user] r.basin ? for plane geometry of polygon shapefiles

[Marco Jorge]

Hi,

I have 10k small polygons stored in a shapefile and in raster format (nr classes = nr of basins).   
I am interested in getting some planar geometry information for each polygon.
I have 3 problems, not considering the lack of knowledge: 

- no DTM; 
- no channels; 
- try to foul r.basin with the shapefile

Can you think of a way to pick the module and its code to calculate the indices in the end of the post? 
Can anyone point me a way to pick up the major axis instead of the lenght of the main channel ? 
Any hint on major (or minor) axis extraction?

Should I try other approach? 

Thanks in advance
Marco


"
	* The circularity ratio: is the ratio between the area of the basin and the area of the circle having the same perimeter of the basin.
	* The elongation ratio: is the ratio between the diameter of the circle having the same area of the basin and the length of the main channel.
	* The compactness coefficient: is the ratio between the perimeter of the basin and the diameter of the circle having the same area of the basin.
	* The shape factor: is the ratio between the area of the basin and the square of the length of the main channel
"
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