OpenJUMP does exactly this in one procedure I.e. simplifying polygon
covergages... (see menu tools>generalization>simplify polygon coverage)
you would only need to call the function. Or you just look how it has
been implemented based on Jump/JTS functonality (the source code is on
the SVN)
stefan
Martin Davis schrieb:
I assume that your dataset forms a polygonal coverage, right? If so,
you can't just simplify each polygon individually - you need to process
them all together, to ensure that coverage topology is maintained.
In this case, you need to do the following:
- dissolve the boundaries of the polygons to form unique line segments
- merge the line segments into linestrings which do not cross
- simplify the resulting linestrings (using
TopologyPreservingSimplifier, to avoid introducing intersections'
- polygonize the resulting line set
- use point-in-polygon tests to reattach the original polygon attributes
to the simplified polygons.
You can do all this with the JUMP and JTS APIs - but there will be a bit
of code required to glue all the pieces together.
Chris Huyler wrote:
We currently use the JUMP API to convert a large ESRI SHP file of all
the zip codes in the U.S. into a map that shows specific sales
territories. The problem is that this file is over 20MB and I'd like
a way to reduce it's size so it can be loaded into a flash
application. Ideally under 1MB.
Is there a way to simplify and reduce the size of shape files with JUMP?
I found a website application at http://www.mapshaper.org/ that lets
me do this but I really need to automate the process so that when
sales territory alignments change the map is automatically updated.
Thanks,
-Chris
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