Hi GRASS users,
I have laid the grids on my raster map by d.grid. I am facing two two problems. d.grid had parameters like:
d.grid size=value [color=name] [origin=easting,northing]
1. What is the use of [origin=easting,northing]. Even if I mention a particular
lat-long value (eg. 25,70), the grid overlays in the whole map irrespective of the lat-long values mentioned by me and the same thing happens if I don't mention any value in the origin (i:e. the grid is overlayed in the whole map).
2. I want to calculate the number of pixels falling to a particular category say
water,forest,agriculture etc. in each grid. How should I proceed to begin with
a single grid and eventually covering all the grids in the area of interest.
I would be thankful for all your suggestions.
regards,
uttam.
_________________________________________________________________
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I have laid the grids on my raster map by d.grid. I am
facing two two problems. d.grid had parameters like:
d.grid size=value [color=name] [origin=easting,northing]
1. What is the use of [origin=easting,northing]. Even if I mention a
particular lat-long value (eg. 25,70), the grid overlays in the whole
map irrespective of the lat-long values mentioned by me and the
same thing happens if I don't mention any value in the origin (i:e.
the grid is overlayed in the whole map).
origin=easting,northing mearly shifts the grid in x,y space, it doesn't
create a bounded grid. For that you might want to try v.mkgrid.
2. I want to calculate the number of pixels falling to a particular
category say water,forest,agriculture etc. in each grid. How should I
proceed to begin with a single grid and eventually covering all the
grids in the area of interest.
A way this could be done is with a bash script.
That might look something like:
g.region rast=raster_map # (for resolution)
for ROW in 1 2 3 4 ... ; do
NORTH=<figure out north bound from $ROW number>
SOUTH=<figure out south bound from $ROW number>
for COL in 1 2 3 4 ... ; do
EAST=<figure out east bound from $COL number>
WEST=<figure out west bound from $COL number>
g.region n=$NORTH s=$SOUTH w=$WEST e=$EAST
r.report [options] > stats-grid_$ROW.$COL.txt
done
done
If there are only a few boxes you could do this by hand of course.
although there may be a better way...
v.mkquads may give some ideas also.