Re: Map projections: an Apache SIS - Proj.4 comparison (1/2)
Thanks for the code Martin. Let me know when you are interested in starting that up, I'll give an update on Proj4j's progress - we might have gotten it into LocationTech's repo by then. Best, Rob On Sat, Sep 9, 2017 at 4:12 PM, Martin Desruisseaux < martin.desruisse...@geomatys.com> wrote: > Le 28/08/2017 à 17:34, Rob Emanuele a écrit : > > > Follow up question: is the benchmarking code somewhere that I can > > build on? I'd like to compare how Proj4J would do against SIS and proj.4. > > > I posted a preliminary version of the benchmark code here: > > https://svn.apache.org/repos/asf/sis/release-test/maven/ > src/main/java/org/apache/sis/test/referencing/ > CoordinateOperationComparator.java > > I will try to help for Proj4J wrappers (so it can easily be added to the > tests) later this month, after OGC meeting. > > Martin > > >
Re: Map projections: an Apache SIS - Proj.4 comparison (1/2)
Follow up question: is the benchmarking code somewhere that I can build on? I'd like to compare how Proj4J would do against SIS and proj.4. On Mon, Aug 28, 2017 at 11:30 AM, Rob Emanuelewrote: > This is great work, thanks for posting! Looking forward to the second blog > post. > > On Mon, Aug 28, 2017 at 11:14 AM, Martin Desruisseaux < > martin.desruisse...@geomatys.com> wrote: > >> Hello all >> >> In August 17th 2017, we presented an introduction to Apache Spatial >> Information System (SIS) in the Free and Open Source Software for >> Geospatial (FOSS4G) conference. Discussions about performance and >> accuracy were planed, but skipped because of lack of time. We put the >> intended content in a series of 2 blog posts. The first post, about >> performance, is available at [1]. The key findings are: >> >> * Proj.4 is generally faster than Apache SIS on Java 8. The identified >> cause is the cost of trigonometric functions. >> * Some (but not all) trigonometric functions are much faster in Java >> 9, but we have not yet benchmarked SIS on Java 9. >> * Despite the above, Apache SIS is sometime faster than Proj.4 (400 >> times faster in an extreme case). This can be explained by >> mathematical work done in SIS. >> * Numerical results are in close agreement for map projections, but >> can differ by 1 or 2 metres for datum shifts. This is because of >> different ways to use the EPSG geodetic dataset ("early-binding" >> versus "late-binding" approaches). >> >> More details are given at [1]. A second blog focussed on the accuracy >> topic will be posted later. >> >> Martin >> >> [1] https://www.geomatys.com/wordpress/index.php/2017/08/28/ >> english-proj-4-versus-apache-sis-a-performance-comparison/?lang=en >> >> >> >
Re: Map projections: an Apache SIS - Proj.4 comparison (1/2)
This is great work, thanks for posting! Looking forward to the second blog post. On Mon, Aug 28, 2017 at 11:14 AM, Martin Desruisseaux < martin.desruisse...@geomatys.com> wrote: > Hello all > > In August 17th 2017, we presented an introduction to Apache Spatial > Information System (SIS) in the Free and Open Source Software for > Geospatial (FOSS4G) conference. Discussions about performance and > accuracy were planed, but skipped because of lack of time. We put the > intended content in a series of 2 blog posts. The first post, about > performance, is available at [1]. The key findings are: > > * Proj.4 is generally faster than Apache SIS on Java 8. The identified > cause is the cost of trigonometric functions. > * Some (but not all) trigonometric functions are much faster in Java > 9, but we have not yet benchmarked SIS on Java 9. > * Despite the above, Apache SIS is sometime faster than Proj.4 (400 > times faster in an extreme case). This can be explained by > mathematical work done in SIS. > * Numerical results are in close agreement for map projections, but > can differ by 1 or 2 metres for datum shifts. This is because of > different ways to use the EPSG geodetic dataset ("early-binding" > versus "late-binding" approaches). > > More details are given at [1]. A second blog focussed on the accuracy > topic will be posted later. > > Martin > > [1] https://www.geomatys.com/wordpress/index.php/2017/08/ > 28/english-proj-4-versus-apache-sis-a-performance-comparison/?lang=en > > >
Map projections: an Apache SIS - Proj.4 comparison (1/2)
Hello all In August 17th 2017, we presented an introduction to Apache Spatial Information System (SIS) in the Free and Open Source Software for Geospatial (FOSS4G) conference. Discussions about performance and accuracy were planed, but skipped because of lack of time. We put the intended content in a series of 2 blog posts. The first post, about performance, is available at [1]. The key findings are: * Proj.4 is generally faster than Apache SIS on Java 8. The identified cause is the cost of trigonometric functions. * Some (but not all) trigonometric functions are much faster in Java 9, but we have not yet benchmarked SIS on Java 9. * Despite the above, Apache SIS is sometime faster than Proj.4 (400 times faster in an extreme case). This can be explained by mathematical work done in SIS. * Numerical results are in close agreement for map projections, but can differ by 1 or 2 metres for datum shifts. This is because of different ways to use the EPSG geodetic dataset ("early-binding" versus "late-binding" approaches). More details are given at [1]. A second blog focussed on the accuracy topic will be posted later. Martin [1] https://www.geomatys.com/wordpress/index.php/2017/08/28/english-proj-4-versus-apache-sis-a-performance-comparison/?lang=en