Re: Map projections: an Apache SIS - Proj.4 comparison (1/2)

[Rob Emanuele]

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 Emanuele  wrote:

> 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)

[Rob Emanuele]

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)

[Martin Desruisseaux]

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