Affine transforms - matrix algebra

Martin Desruisseaux martin.desruisseaux at geomatys.fr
Thu Jul 12 02:50:27 PDT 2012


Le 12/07/12 11:28, Pavel Safrata a écrit :
>>>> * Rename 'getConcatenation' as .. well .. 'getPrependage' :-)
>>> I missed that method... What would its function? Or are we are 
>>> talking about something like a 'getTransformCoefficients()' method?
>> This method is similar to concatenate (prepend) except that it is 
>> defined on parent Transform class and returns the result in a new 
>> Transform instance (allows for multiplicating arbitrary - possibly 
>> immutable - transfroms).
> What about something like getCompound(Transform)? Probably switching 
> its meaning so that a.getCompound(b) returns equivalent transform to 
> a.append(b).

I'm not sure if this is relevant to JavaFX Affine, but in the vocabulary 
used by the ISO 19111 international standard (Geographic information — 
Spatial referencing by coordinates), "compound" and "concatenated" are 
slightly different concepts. We have "compound" coordinate systems, but 
"concatenated" transforms. If consistency with ISO 19111 was considered 
a worthy bonus, then "concatenate" or "getConcatenation" would be quite 
appropriate vocabulary.

Not exactly ISO 19111 but closely related, the Open Geospatial 
Consortium defined this method:

http://www.geoapi.org/3.0/javadoc/org/opengis/referencing/operation/MathTransformFactory.html#createConcatenatedTransform%28org.opengis.referencing.operation.MathTransform,%20org.opengis.referencing.operation.MathTransform%29

Martin



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