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From "Martin Desruisseaux (JIRA)" <>
Subject [jira] [Commented] (SIS-212) Coordinate operation methods to implement
Date Mon, 14 Mar 2016 10:00:41 GMT


Martin Desruisseaux commented on SIS-212:

Hello Joseph

In my understanding, the next step would be to write a document describing the project that
you would like to do. You can copy and edit elements from this page as you wish. Instructions
are available there:

The document could be written in a Google doc, or on a SIS wiki page (,
or in other ways as you prefer. We could propose modifications and do some cycles until the
proposal is ready for submission on the Google web site.

Would this approach be okay?

> Coordinate operation methods to implement
> -----------------------------------------
>                 Key: SIS-212
>                 URL:
>             Project: Spatial Information Systems
>          Issue Type: Task
>          Components: Referencing
>    Affects Versions: 0.6
>            Reporter: Martin Desruisseaux
>            Assignee: Martin Desruisseaux
>              Labels: gsoc2016, java, mentor
>             Fix For: 0.6, 0.7
> This is an umbrella task for some coordinate operation methods not yet supported in Apache
SIS. Coordinate operations include _map projections_ (e.g. Transverse Mercator, Lambert Conic
Conformal, _etc._), _datum shifts_ (e.g. transformations from NAD27 to NAD83 in United States),
transformation of vertical coordinates, _etc_. We can of course not list all possible formulas
that we do not support, but this JIRA task lists at least some of the operations listed in
the EPSG guidance notes.
> The main material for this work is the EPSG guidance notes, which can be downloaded freely
from the following site:
> {panel}
> IOGP Publication 373-7-2 – Geomatics Guidance Note number 7, part 2
> Coordinate Conversions and Transformations including Formulas
> {panel}
> Google summer of code students interested in this work would need to be reasonably comfortable
with the Java language (but not necessarily with the JDK library at large, since this work
uses relatively few JDK classes outside {{Math}}), and in mathematic. In particular, this
work requires a good understanding of _affine transforms_: their representation as a matrix,
and how to map a term in a formula to a coefficient in the affine transform matrix.
> Apache SIS has one advanced feature which is not easily found in popular geospatial software
or text books: the capability to compute the _derivative_ (or more precisely, the _Jacobian_)
of a transformation at a given point. Implementation of this feature requires the capability
to find the analytic derivative of a non-linear formula and to simplify it.
> Implementations of those formulas take place in one of the {{org.apache.sis.referencing.operation}}
sub-packages ({{projection}} or {{transform}}). Implementations of JUnit test happen partially
in Apache SIS, and partially in the ["conformance module" of the GeoAPI project|],
if possible through the Geospatial Integrity of Geoscience Software (GIGS) tests.

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