FYI, as of r3078 the mis-port is fixed in GEOS.
Still interested in the result after self-noding.
Thanks !
--strk;
On Thu, Jul 01, 2010 at 10:59:12PM +0200, strk wrote:
On Mon, Jun 21, 2010 at 09:13:16AM -0700, Martin Davis wrote:
strk,
The JTS Developer's Guide is a bit confusing. The geometry given in the
example is NOT the geometry depicted in the illustration. (This is a
doc bug - but Im not sure if and when I can fix it).
When I run the geometry below in JTS I get:
Polygons:
GEOMETRYCOLLECTION (
POLYGON ((189 98, 83 187, 185 221, 325 168, 189 98)),
POLYGON ((185 221, 88 275, 180 316, 292 281, 185 221)))
Dangles:
MULTILINESTRING ((185 221, 100 100),
(0 0, 10 10))
I believe this is the expected result.
Uhm, that's w/out self-noding, right ?
--strk;
Hope that helps
Martin
strk wrote:
Martin, I'm adding a testcase for the Polygonizer using example from :
JTS Developer's Guide, Chapter 6 - Polygonization
Here's the input, represented as a collection:
GEOMETRYCOLLECTION(
LINESTRING(0 0, 10 10),
LINESTRING(185 221, 100 100),
LINESTRING(185 221, 88 275, 180 316),
LINESTRING(185 221, 292 281, 180 316),
LINESTRING(189 98, 83 187, 185 221),
LINESTRING(189 98, 325 168, 185 221))
)
When passing it into the Polygonizer class I get
2 rings, no cut or invalid edges and 3 dangles.
Also notable is that of the 3 dangles, 2 are identical
and specificall are the isolated edge (first geometry
in the collection).
The example in the guide suggests the rings should
be 3 instead, and that there should be one cut
edge (represented in blue) and 2 dangles
the red ones.
Does it sound as a bug in GEOS or does JTS give the
same results ?
Note that forcing proper noding using the union trick
does give the 3 expected rings, but still lacks the
cut edge and duplicates the dangle.
Thanks in advance.
--strk;
() Free GIS Flash consultant/developer
/\ http://strk.keybit.net/services.html
--
Martin Davis
Senior Technical Architect
Refractions Research, Inc.
(250) 383-3022
--
() Free GIS Flash consultant/developer
/\ http://strk.keybit.net/services.html
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