Hi,
I really love how GRASS is working, but I have some problems
1) I'm trying to digitilize polygons with GRASS 5, I use v.digit but the
results were not polygons... doing a v.to.rast doesn't result in an
area.Now I'm trying to use OpenEV to do the work. Is there any easy way to
do this in GRASS ? I know that probably GRASS 5.7 is better, but I don't
know how to deal with the database subsystem.
2) I have, in this way, a set of ShapeFiles, that I want to put together
in only one vector file, I use v.path after import the shapefiles but the
problem is that I miss the "identity" of each polygon, by using r.what I
realize that now they have the same name.... Any suggestions ? How can I
deal with the limits between neighbor areas... becuase they are the same
line
3) I would like to extract from these polygons the corresponding
centroids, an assign to each a time series data in order to do a temporal
and spatial analysis of my data.... How can I do it ? I know that probably
using R, but again I have no idea about how to do it.
Thanks
D
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It's informative and essential.
On Sat, 16 Oct 2004, DrakeGis wrote:
Hi,
I really love how GRASS is working, but I have some problems
1) I'm trying to digitilize polygons with GRASS 5, I use v.digit but the
results were not polygons...
Did the areas not snap closed properly? Make sure the scale of your map is set properly in the vector map header details (the first think you are asked to update in v.digit) as if it is wrong the snapping threshold in v.digit will not be a useful value. If your polygons contain lines and not area edges (i.e. boundaries) use v.line2area to fix that.
2) I have, in this way, a set of ShapeFiles, that I want to put together
in only one vector file, I use v.path after import the shapefiles but the
problem is that I miss the "identity" of each polygon, by using r.what I
realize that now they have the same name.... Any suggestions ? How can I
There is no easy way to work around that. You have to make sure that all your vector entities have unique attribute ID numbers before patching them together.
Paul
Thanks Paul,
But I still have problems...
1) I'm trying to digitilize polygons with GRASS 5, I use v.digit but the
results were not polygons...
Did the areas not snap closed properly? Make sure the scale of your map is
set properly in the vector map header details (the first think you are
asked to update in v.digit) as if it is wrong the snapping threshold in
v.digit will not be a useful value. If your polygons contain lines and not
area edges (i.e. boundaries) use v.line2area to fix that.
The Snaps are fine, I'm sure. Anyway I use v.line2area, and then during
the execution of v.to.rast, I saw 0 areas to be converted....
2) I have, in this way, a set of ShapeFiles, that I want to put together
in only one vector file, I use v.path after import the shapefiles but
the
problem is that I miss the "identity" of each polygon, by using r.what I
realize that now they have the same name.... Any suggestions ? How can I
There is no easy way to work around that. You have to make sure that all
your vector entities have unique attribute ID numbers before patching them
together.
What you mean by vector entities, I have two polygons... or are
speacking about the lines that form such polygons ?
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It's informative and essential.
On Sat, 16 Oct 2004, DrakeGis wrote:
What you mean by vector entities, I have two polygons... or are
speacking about the lines that form such polygons ?
I think I mean that all the lines that form the first polygon/area should have the same attribute number as each other, and that all the lines that form the second area should have the same attribute number as each other, but different from the lines that form the first area.
It sounds a bit like you had two maps, each with one area, and all the lines forming the areas in both maps all had the same attribute number. But I'm not too sure.
Paul