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Posted to dev@sis.apache.org by Martin Desruisseaux <ma...@geomatys.com> on 2020/08/10 11:32:14 UTC

Re: Equation on the web page (was: Should we open a SIS channel on Slack?)

Hello Shah

Note: this is a different thread than the original one about Slack channel.


Le 10/08/2020 à 12:38, shah.ahmed@seanews.co.uk a écrit :

> I'm looking at the equations and the website pages, I assume that this 
> is all to do with Mapping?
>
I'm not sure which pages we are talking about? The Apache SIS developer 
guide [1] and the Javadoc (e.g. [2]) have some equations, but most of 
them are somewhat specific to SIS. For example some equations give the 
matrices created by SIS for representing a unit conversion. If you are 
looking for map projection formulas, a good reference (the main 
reference used by SIS actually) is:

    EPSG Guidance Note 7-2
    Coordinate Conversions and Transformations including Formulas
    https://epsg.org/guidance-notes.html

Wikipedia and Mathworld are also useful references (there is links to 
those pages in SIS javadoc), but they usually have formulas for a 
spherical Earth only (i.e. ignoring the flattening at poles).

     Martin

[1] http://sis.apache.org/book/en/developer-guide.html
[2] http://sis.apache.org/apidocs/org/apache/sis/referencing/cs/CoordinateSystems.html#swapAndScaleAxes(org.opengis.referencing.cs.CoordinateSystem,org.opengis.referencing.cs.CoordinateSystem)