[Geotools-devel] CRS milestone: working version of MathTransformFactory

[Martin D. <mar...@te...>]

The new CRS API (org.geotools.referencing) now has a working 
MathTransformFactory. MathTransforms in the new API are very similar to 
the old API. The most significant change is in the way math transforms 
are registered (i.e. MathTransformProvider). The list of available math 
transforms is no-longer hard-coded. Instead, it is now provided in the 
following file:

META-INF/services/org.geotools.referencing.operation.MathTransformProvider

If a new JAR file is dropped in the classpath with such META-INF 
informations, all MathTransform declared in it will be automatically 
recognized by MathTransformFactory.

Currently ported MathTransforms are:

    - "Affine"
    - "Logarithmic"
    - "Exponential"
    - "Geocentric_To_Ellipsoid"
    - "Ellipsoid_To_Geocentric"

as well as the following operations on MathTransform:

    - concatenate
    - pass through

An other difference (compared to the old API) is that transform are now 
identified using an OpenGIS's Identifier interface rather than a plain 
string. Concequently, it is possible to use many identifier for the same 
transform. For example, the Geocentric to Ellipsoid transform is 
currently declared with 2 identifiers:

     new Identifier(Citation.OPEN_GIS, "Geocentric_To_Ellipsoid"),
     new Identifier(Citation.EPSG,     "9602")

This means that, when creating a MathTransform, the two following lines 
are synonymous:

    factory.createParameterizedTransform("Geocentric_To_Ellipsoid", ...)
    factory.createParameterizedTransform("EPSG:9602", ...)

This thing was not possible in the old API.

Last note: the WKT parser has not yet been fully ported. This is means 
that we can't run test script on new MathTransform yet. Concequently, we 
are not yet ready to port Rueben's work (Molodenski Transform, etc.). I 
will sent a note when the port of WKT parser will be finished.


	Martin.