Hi Martin,
I just noticed that the code we use for the CombineSelectedFeature plugin
is very close to GeometryFactory.buildGeometry() method.
Hence, I checked buildGeomery code and found that in the particular case
of two adjacent polygons, it will also produce an invalid geometry.
I don't know
Hi Martin,
I just noticed that the code we use for the CombineSelectedFeature plugin
is very close to GeometryFactory.buildGeometry() method.
Hence, I checked buildGeomery code and found that in the particular case
of two adjacent polygons, it will also produce an invalid geometry.
And
Hi Larry,
Thanks for the input,
I followed your suggestion to add a warning in the status bar.
I did the test for the MultiPolygon case only though.
Not sure it is useful in the general case. Maybe it would be
better to make the plugin consistent with the edit tools option
accept invalid
Hi Michaël,
do you mean the option
OptionsView/EditPrevent edits resulting invalid geometries?
I am not understanding this option.
What is the use of drawing a selfintersection polygon?
1. In my opinion a program should never *compute* invalide
geometries like multipolygon if it is not
a valid
Hi,
sorry, the last point 2 should be a 3 :-(
uwe
Am 10.04.2013 10:24, schrieb Uwe Dalluege:
Hi Michaël,
do you mean the option
OptionsView/EditPrevent edits resulting invalid geometries?
I am not understanding this option.
What is the use of drawing a selfintersection polygon?
1. In
Hi,
1) It should never happen but we are living in a not perfect world and it
happens and will always happen.
2) For some use cases the invalid geometries may be good enough. Typical
examples are polygons with tiny self-intersections or inner circles with only
two vertices (A-B-A).
Hi Martin, Michaël and Stefan,
thank you very much for this detailed clarification!
Is it in OJ possible to check first for valid
geometries when
Combine Selected Features
or is this a great problem?
If it is a great problem maybe it is better
Combine Selected Features
makes always a
Hi,
Is it in OJ possible to check first for valid
geometries when
Combine Selected Features
or is this a great problem?
If it is a great problem maybe it is better
Combine Selected Features
makes always a geometrycollection?
There are several points :
1 - in the step by step process you
2 - I agree that in this case, building a valid GeometryCollection
is better than building an invalid Multipolygon, even if
GeometryCollection are much less useful (many operations
accepting MultiPolygon will fail on GeometryCollection).
If if no one has any objection, I propose to do the
Hi Michaël,
Echoing what I think you are proposing:
1) when Combine Selected Features is invoked, a basic topology validity
check is done on the result.
2) Any errors should be reported in the status bar or the Output Window.
3) If an invalid geometry results from building a MultiPolygon, a
Hi,
I get the error:
The new geometry is invalid. Cancelled.
and I am not shure whether this error is correct.
1. Switch Snap to vertices option.
2. Draw a rectangle.
3. Draw a second rectangle with two identical
vertices from the first rectangle (with snap).
4. Select the two rectangles and
,
263 125,
175 125
)))
It cannot be added as WKT either.
-Jukka-
-Alkuperäinen viesti-
Lähettäjä: Uwe Dalluege [mailto:uwe.dallu...@hcu-hamburg.de]
Lähetetty: 8. huhtikuuta 2013 13:06
Vastaanottaja: Devel Jump
Aihe: [JPP-Devel] The new geometry
Hi,
if you put a third geometrie to the two polygons,
for instance a linestring, and combine them
you will receive a geometrycollection
and not a multipolygon.
The geometrycollection causes *no* errors
but the multipolygon.
Uwe
Am 08.04.2013 12:05, schrieb Uwe Dalluege:
Hi,
I get the
Hi,
so - well the situation is not so nice, as it should be valid. However,
the JTS TestBuilder says the Multi-Polgyon is invalid because of
Self-intersection at or near point (175.0, 125.0, NaN)
Same message appears when you try to add it as a new feature.
maybe you can make it valid before
Hi Stefan,
I am afraid I do not understand :-(
Do you think this is a bug in OJ?
The multipolygon causes an error
the geometrycollection not.
Is this behaviour OGC-conform (simpel features...)?
What do you think?
uwe
Am 08.04.2013 16:36, schrieb Stefan Steiniger:
Hi,
so - well the situation
Hi Uwe,
I am not sure I would call it a bug. OJ, should (try to) create data
that are OGC conform, but in this case it doesn't. Which means, the case
needs special treatment, but this is not implemented.
That the multi-polygon causes an error is with the OGS SF specification
= correct.
Hi Uwe, Stefan,
OpenJUMP (JTS) is right, this MultiPolygon is not OGC conform
Here is the citation :
Multipolygon
2. The Boundaries of any 2 Polygons that are elements of a MultiPolygon
may not ‘cross’ and may touch
at only a finite number of points. (Note that crossing is prevented by
As Michael and Stefan point out, Polygons in a MultiPolygon must be
edge-disjoint (which another way of stating the formal definition must
only touch at a finite number of points. If they touched along an
edge, that would cause an infinite number of points to be coincident).
Another way of
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