Not all operations are 2D, just 99% of them. Some of the overlay ops
try to compute "correct" derived Z-values.
P
On Jan 12, 2009, at 10:04 AM, Sean Gillies wrote:
So, the dimension argument in GEOSCoordSeq_create is ignored unless
the active sequence implementation takes dimensions other than 3?
Why is GEOS's default sequence 3D when all operations are 2D?
Sean
On Jan 12, 2009, at 10:56 AM, Martin Davis wrote:
Actually JTS implements this correctly. The return value from
getDimension is computed by the implementation of
CoordinateSequence. In the case of DefaultCoordinateSequence
(which by the way is deprecated and replaced by
CoordinateArraySequence) the value is alway 3, since the Coordinate
representation used by these sequences always allows for 3 ordinates.
In the case of PackedCoordinateSequence the dimension can be
selected on creation, and this is the value that is returned by
getDimension.
Sanak wrote:
Hi list,
I don't know that this is a known bug, but
CoordinateArraySequence.getDimension() method always return 3.
[trunk/source/headers/geos/geom/CoordinateArraySequence.h - line 88]
size_t getDimension() const { return 3; }
JTS(JTS Topology Suite) seems to be also the same.
[jts/src/com/vividsolutions/jts/geom/
DefaultCoordinateSequence.java - line 95]
public int getDimension() { return 3; }
I don't know that this is a specification or not...
Regards,
Sanak.
2009/1/12 Sean Gillies <sgill...@frii.com
<mailto:sgill...@frii.com>>
I'm finding that GEOSCoordSeq_getDimensions returns 3 no matter
what
# Accessing libgeos_c via Python ctypes
>>> s = lgeos.GEOSCoordSeq_create(2, 2)
>>> ndim = c_int()
>>> lgeos.GEOSCoordSeq_getDimensions(s, byref(ndim))
1
>>> ndim
c_long(3)
Is this a known bug? Looks like we're only testing creation of 3D
coordinate sequences in
http://trac.osgeo.org/geos/browser/trunk/tests/unit/capi/GEOSCoordSeqTest.cpp
--
Sean Gillies
http://sgillies.net
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