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JTS uses the FastNodingValidator to check for correctly noded line
arrangements. Basically it checks for any interior-interior segment
intersections, using indexing to speed things up.<br>
<br>
And yes, the OGC operation semantics aren't fully capable when it
comes to more specific uses like checking noding. That's one reason
I introduced the boundary-node rule.<br>
<br>
The Polygonizer is fine with closed lines (as long as, as always,
the linework is FULLY noded).<br>
<br>
This issue is just one more example of a robustness failure. <br>
<br>
On 4/2/2012 2:46 AM, GEOS wrote:
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cite="mid:053.b3ed9a1095b0ac526b4622274ba8e9f5@osgeo.org"
type="cite">
<pre wrap="">#527: Union and UnaryUnion both fail at correctly node input lines
------------------------+---------------------------------------------------
Reporter: strk | Owner: geos-devel@…
Type: defect | Status: new
Priority: major | Milestone: 3.3.4
Component: Default | Version: 3.3.3
Severity: Unassigned | Keywords:
------------------------+---------------------------------------------------
Comment(by strk):
Uff, ST_IsSimple isn't a good check when it comes to _closed_ lines, in
that they have no bounday so the node would be considered as an
interior/interior intersection, like here:
MULTILINESTRING((0 0, 10 0, 10 10, 0 0), (0 0, -10 0, -10 -10, 0 0))
The boundary node rule is really getting in my way.
@mbdavis : how can I check for correct noding ? And is Polygonizer happy
with noding which involves closed lines ?
/me goes on to try again the polygonizer call with more closed lines.
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