[GRASS-user] newbie question - vector/raster processing

GRASS GRASS user
1

Dear All,

I am having some problems working out how to analyse some data.

I have created a segmented vector file (through region growing - image segmentation using the terralib library) which I hope to represents different forest classes. I have classified the segmented image file into 10 unknown classes (10 000 polygons with 10 different classes) based on some recent imagery data. The main aim of this was to improve the boundary of the forest classes.

I have then imported the classified vector file into grass. I now would like to populate the forest class by intersected the polygons in my new vector map with an existing forest class map and take the most common forest type from the old map. I was thinking i could rasterise the old forest class map and some how count the number of cells for each class within each polygon and some how choose the most common class.

Any suggestions on how to do this would be much appreciated.

Andrew

2

On 10/16/07, andrew haywood <ahaywood3@gmail.com> wrote:

I have then imported the classified vector file into grass. I now would like to populate the forest class by intersected the polygons in my new vector map with an existing forest class map and take the most common forest type from the old map. I was thinking i could rasterise the old forest class map and some how count the number of cells for each class within each polygon and some how choose the most common class.

This is probably of some help <http://grass.gdf-hannover.de/wiki/Aggregate_Values>. r.statistics might be useful, but the wiki entry gives you quite a thorough description. IMHO, it is far harder than it should be. starspan might also be an option.

Regards,
Jose