[OSGeo-Discuss] Generic Geometry Library (ggl)

Barend Gehrels Barend.Gehrels at geodan.nl
Thu Feb 19 10:17:46 PST 2009

Hi Bart,

Some details can be found here: 

You can get an impression of speed improvement there, for our testcases.

There are some more measurements to be done and more details will be 
added. Therefore I'll keep them currently anonymous. In the end we'll 
publish the comparison sources, it first has to mature a bit and be 
described better.

Best regards, Barend

Bart van den Eijnden (OSGIS) wrote:
> Hi Barend,
> "The performance of the library is compared with other C++ OS GIS 
> libraries and we measured that the library seems to be much faster 
> than most of them, caused by the template approach. "
> Do you have any more details on this performance study? Which 
> libraries (GEOS?, ...) did you compare to, and how much speed 
> improvement was there in your test cases?
> Best regards,
> Bart
> Barend Gehrels wrote:
>> Dear list,
>> It is a pleasure for us to announce the Generic Geometry Library (ggl).
>> It is an Open Source library, written in C++. The library is template 
>> based, and generic. With generic we mean that the algorithms work not 
>> only with the provided geometries, but also with geometries that are 
>> defined by the library user, such as legacy points, custom 
>> linestrings, etc.
>> Because of this the library is following OGC conventions loosely, not 
>> strictly. All algorithms are implemented as standalone functions, 
>> instead of methods on geometries. Nevertheless, OGC conventions, 
>> names and meanings are followed as much as possible. Not all OGC 
>> algorithms are already implemented. On the other hand the library 
>> offers other things such as distance calculations over the globe.
>> So it is a library modelled as the C++ std:: library and as most 
>> Boost libraries are. The library is proposed to Boost (Boost is a 
>> well-known peer reviewed C++ Library Collection). It is following the 
>> Boost Software License, which is a permissive Open Source License.
>> The library is accessible via SVN at Boost: 
>> https://svn.boost.org/svn/boost/sandbox/ggl but can also be 
>> downloaded from http://geometrylibrary.geodan.nl. Much documentation 
>> and many examples can be found there. Note for example the Custom 
>> Linestring example showing things which cannot so easily be done with 
>> non-template libraries.
>> The library contains projections from PROJ4, converted to C++ . We 
>> first wanted to include PROJ4 as an example, like we did with 
>> ShapeLib and GD. However, we concluded that they fit better being 
>> implemented as C++ templates, so they are automatically converted (it 
>> is reproducable). Like there is a PROJ4 Javascript branch, this might 
>> be considered as a PROJ4 C++ branch. We like your opinion about this.
>> The library is in "preview 4", it has been submitted as preview to 
>> Boost three times, last year. Based on many comments the library has 
>> been enhanced. We think it is now in a proper shape to be used, and 
>> that algorithms can now be added without that everything is 
>> restructured again.
>> The performance of the library is compared with other C++ OS GIS 
>> libraries and we measured that the library seems to be much faster 
>> than most of them, caused by the template approach.
>> We welcome any type of comment, opinion or cooperation.
>> Barend Gehrels, Geodan, Amsterdam, the Netherlands
>> Bruno Lalande, Paris
>> _______________________________________________
>> Discuss mailing list
>> Discuss at lists.osgeo.org
>> http://lists.osgeo.org/mailman/listinfo/discuss

Barend Gehrels
Geodan Holding b.v.
President Kennedylaan 1
1079 MB Amsterdam
The Netherlands
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E-mail: barend.gehrels at geodan.nl
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