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| GeoCommunity Mailing List |
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| Mailing List Archives |
| Subject: | [gislist] donut polygons - SUM |
| Date: |
12/12/2003 03:30:00 AM |
| From: |
Till Bergmann |
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Hi All,
thanks for all of Your quick help yesterday. As promised here are the
answers I received so far.
Monica, actually I was very close to the answer yesterday when I came up
with the question to the List. I just didn't figure out that the script
must execute a size comparison on the resulting polygons. Probably a "pre
morning coffee"-problem :-)
Avenue is very easy to learn, because you deal with the problems you can
solve with it every day. So the practice is not abstract like with other
programming languages you could learn. The question is if it is still
worthwhile. Nobody really knows how much longer ArcView 3.X will exist...
Some German ESRI-dudes say "at least 2 more years"! But they are far from
Redlands.
Greetings,
Till
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Answers:
Hi -
Make a shapefile - say a rectangle that encompasses the whole extent of
your
shapefile. Union the two together and presto, your holes should be filled.
Then code the attributes of your holes accordingly.
Saying that though used to do this in AI - it should work in AV but may
not.
You will probably either need the geoprocessor or xtools.
Good luck
Charlotte
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a quick thought - (mind you, these are before my morning coffee...)
~ if the holes are all relatively small (as compared with the smallest of
the polygons), then you might digitize a new shapefile consisting of a
bounding box, then perform a union on the new shapefile with the one
containing the polygons (you can use the GeoProcessing extension), then
edit
the resulting shapefile by (a) deleting the polygon filling the space
between the original polygons, then (b) selecting all remaining polygons
and
merging them ("union features" item on Theme menu), then (c) exploding all
to return to original polygons. Not sure if the attributes will carry over
through all these steps so you may have to rejoin with a spatial join
afterwards.
good luck.
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Potentially you could created a coverage/geodatabase and BUILD/CLEAN the
new coverage with a fuzzy tolerance that would "fill" the holes. But
because the bounding lines would also be effected, using the original
poly's edges lines you could then recut the larger polys. Either way, it
sounds like a CLEAN/BUILD process.
Good luck
RSL
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If, for example, your polygons are coded so that it knows which are the
"true" polygons, and which are the "holes" (i.e. tpe = 1 for the "real" and
type = 0 for the "holes)...just select where type = 1 and then save as a
separate shapefile - the "holes" will be left behind.
We do this all the time.
If you need more help, feel free to call or write.
Korine R. Leonard
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