[GRASS-stats] creating a grid from a contour vector shape

[alexandre villers]

Good evening,

I'm a beginner with GRASS. In order to analyse a dataset on the spatial distribution of a bird's species, I wanted to create many spatial grids (with increasing cell size, from 500 to 15000 meters)and then count birds in each cell.

I started with
v.in.ogr to import a countour shape file for my observation window
v.to.rast (countour)followed by r.mask to limit the work on that contour limit
finally, v.mkgrid to create the grid with the required spatial resolution.

I'm looping this with R and also added 10 different origins (lower left corner of grids) in order to average counts, specially for large grids.

The next step is to overlay within R, using the sp packages, the layer of points and the grid. The problem (which, by taking the time of reflexion, would have been clear before running the script !) is that some grid cells are cut many times by the countour vector, leading to unique cells having many different IDs (which I didn't want).

So can I overlay that contour vector on a grid while keeping the cells (intact) intersected by the countour limit (instead of clipping them) ?

Hope I was clear enough...

Best regards

Alex
Alexandre Villers
PhD. Student
Team Biodiversity
CEBC CNRS
79360 Beauvoir sur Niort


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