Questions tagged [cgal]
CGAL (Computational Geometry Algorithms Library) is an open-source software library that provides efficient and reliable algorithms in computational geometry.
11 questions
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3D centroid in PostGIS
How could I find the 3D centroid of this feature in PostGIS:
SELECT
ST_AsText(
ST_GeomFromText('POLYGON Z ((0 0 0, 1 0 0, 1 0 1, 1 1 1, 0 1 1, 0 0 1, 0 0 0 ))')
) geom;
...
- 10.9k
4
votes
1
answer
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Why is this polygon not planar for PostGIS
Why is the following Polygon Z not planar for PostGIS 3.4.0dev (3.3.0rc2-335-gae95dd219)?
SELECT ST_IsPlanar(
ST_GeomFromText(
'POLYGON Z ((
3021241.9043000005 2037823.3759000003 262....
- 10.9k
3
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1
answer
315
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PostGIS sfcgal ST_3DArea
I want to compute surface areas of a large CityGML data set. However, I ran into some issues, which I could not resolve or fully understand.
The error message is the following:
Polygon is invalid : ...
0
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0
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220
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File VERSION or include/CGAL/version.h are missing, required by release-build
I'm trying to compile CGAL libraries on fedora 27
but when I compile them using cmake ,it show's the following message:
CMake Error: Unable to open check cache file for write. /home/xx/Documents/...
- 101
1
vote
1
answer
61
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error while running CGAl pacakge examples
I'm try to run "map_3_with_colored_facets" example which included in CGAL package
but I faced some errors , it cannot read "Combinatorial_map.h" methods
-cm.make_combinatorial_hexahedron() isn't a ...
- 13
-1
votes
2
answers
381
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Adding Cgal headers after building package examples?
I'm beginner at using Cgal .
I'm trying to run the examples which included in the CGAl package,
I built the examples using Cmake and "make" command.
but I'm facing a problem in including the header ...
- 13
3
votes
2
answers
904
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Postgis exact geometry from text
I have some geometry in cgal that I would like to export to postgis. The kernel I'm using is the same as what sfcgal uses (exact predicate exact construction), but I'm encountering some errors in ...
- 303
2
votes
1
answer
702
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SFCGAL compilation: How to specify CGAL path?
I'm a Linux newbie but nevertheless I want to install SFCGAL on OSGeoLive Virtual Machine (this is Ubuntu 14.04.4. LTS trusty). So first of all I had to get the dependencies, e.g. CGAL. Unfortunately ...
- 23
3
votes
4
answers
985
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How to determine if two points are on the same side of a LineString?
I have two points, A and B, and a line string L. A line string is formed by a sequence of points such that consecutive points are joined by a straight line. This is the same as a LineString in Geos - ...
- 141
3
votes
1
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618
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Using GIS data with CGAL
I read a few posts here at GIS.SE that points to useful algorithms in CGAL. I'd like to test algorithms in CGAL such as medial axis transformation/polygon skeleton extraction, but the examples on the ...
- 11.2k
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2
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How to build pgRouting with CGAL?
When running cmake for CGAL 3.9, I get the following output:
root@postgresql local/CGAL-3.9# cmake -DWITH_CGAL_Qt3=OFF -DWITH_CGAL_Qt4=OFF -DWITH_CGAL_ImageIO=OFF .
-- The C compiler identification ...
- 11