Radim,
Thanks much for the information.
On Thursday, October 30, 2003, at 09:41 AM, Radim Blazek wrote:
On Wednesday 29 October 2003 21:10, you wrote:
However, something is driving me crazy. I've probably missed something,
but hope someone can help me. I've digitized a boundary, but can't
figure out how to turn it into an area. When I do a right-click after
digitizing a shape, the implication is that it will close a polygon,
creating an area. It doesn't seem to do this,however.Right-click does not close the polygon (yes, 'Close line' prompt is not the best).
To do this, new check box ('Close polygon') must be added to interface.
I want to add also option 'Insert automatically new centroid'.
These two options should make digitizing of isolated areas easier.
Now, if you want to create new area as one closed boundary, you have to digitize
the boundary and then to snap last vertex to the first vertex.
Boundary and crosses at the ends must become green not red.
After considerable futzing, that is where I am at now. When I first digitized this, it happened to be in several separate segments (green "x" at intersections). I eventually ran v.clean, separating all segments, followed by v.build.polylines to put them together into a single boundary (one red "x" at the closing intersection). However, I had to do a v.out.ascii, edit the ascii file to get rid of some tiny segments, followed by a v.in.ascii to finally get to a single boundary line.
BTW, there is a bug in vector library and centroid colors are not updated
properly if boundary is closed, opened etc.
This may have caused me to think I had a bad polygon when I was actually OK. However, I regularly ran v.build to look at the messages to see if any centroid I entered actually got linked up to a boundary. In all cases, it was seen by v.build as an isolated centroid (i.e., error).
Also, please note that when I do a v.out.ascii on this boundary file,
it creates a file that GRASS 5.0.x won't parse. I assume that it has
something to do with assigning "B" labels for boundary vertices, rather
than "A" or "L" labels, but I don't know for sure. I haven't yet tried
exporting in version 4 format. Maybe that will work.Vector ascii format is changed, use -o (old) option to get 5.0 format.
That was what I eventually figured out. The message on the TCL dialog box for v.out.ascii describes the -o option as for version 4.
Most probably, the polygon is not closed. What color is the boundary in v.digit?
You could well be right. The polygon is red. Once I managed to get it to orange but still couldn't get the centroid to link up (or perhaps this was where it actually was linked but I didn't know it because of the color update bug).
I have moved and resnapped the polygon closing ends repeatedly, zooming in to as close as I can. I've also tried to adjust the snapping to no avail. I just tried it again, adjusting the snapping to 5m and zooming in to a very close range to reclose the polygon. I then put a centroid in the polygon and exited.
The polygon still doesn't show up as a filled area.
If it helps figure out what may be going on, nothing happens when I click the show attributes button and select either the polygon or a centroid I created.
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Department of Anthropology
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