Thank you for this response. I have looked into GEOS, it appears to be a C/C++
version of the Java Topology Suite, and there does not seem to be much
documentation for GEOS, but I have found the Java Docs for JTS.
Is it correct to say that GEOS does not have a command line interface? It
seems like it may be easiest to try this in UDig and see if JTS works, as I can
tell you that I have not been successful in doing what I want to do with GEOS
in either QGIS or GRASS.
-Thayer
From: Markus Metz <[email protected]>
To: Markus Neteler <[email protected]>
Cc: Thayer Young <[email protected]>; GRASS LIST <[email protected]>
Sent: Sunday, January 18, 2015 5:36 PM
Subject: Re: [GRASS-user] v.select error: point array must contain 0 or >1
elements
On Sun, Jan 18, 2015 at 11:23 PM, Markus Neteler <[email protected]> wrote:
> On Sat, Jan 17, 2015 at 10:12 PM, Thayer Young <[email protected]> wrote:
>>
>> I have two shapefiles that I imported into GRASS 6.4.5 using v.in.ogr. One
>> is a polygon file of building footprints. The second is a polyline of the
>> pavement edges of urban streets. I am trying to convert this into street
>> area. I used v.clean, v.type (to switch from line to boundaries), and
>> v.centroids. This conversion process gives me street areas but also creates
>> doughnut holes corresponding to the area inside of a city block outlined by
>> the streets. For the most part the doughnut holes contain buildings, so I
>> am trying to use v.select to select the areas that do not contain buildings.
>> I have not been able to get anything besides "overlap" to work. Overlap is
>> not good enough though because many of the buildings have shared nodes with
>> the streets, for example where a driveway runs along one side of a house. I
>> checked and my version of GRASS was compiled with the following GEOS details:
>>
>>--with-geos=/Library/Frameworks/GEOS.framework/Versions/3/unix/bin/geos-config
>>
>> Below is an example of an error that I am getting when I try anything
>> besides overlap:
>>
>> v.select --overwrite ainput=EdgePav_cent@PERMANENT binput=Bldg@PERMANENT
>> output=Pav_sel operator=contains
>> WARNING: Vector map <Pav_sel> already exists and will be overwritten
>> Building spatial index...
>> Processing features...
>> ERROR: IllegalArgumentException: point array must contain 0 or >1 elements
>
> In the past few days Markus Metz has fixed some topology issues in
> GRASS GIS 7 (potentially to be backported while that's a big task).
> Do you have any chance to try this in GRASS 7, downloading a version
> newer than RC1 (fixes will go into RC2)?
This seems to be a GEOS problem, not a GRASS problem, because
operator=overlap seems to work, and this the GRASS-internal operator.
All other operators (anything besides overlap) use GEOS, if those do
not work, it is a GEOS problem or the way GEOS is used by v.select.
Markus M
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