Gabriella Turek a écrit :
> The wording in the documentation is ambiguous: it just says the "grid
> has been rotated". My guess is that the grid coverage relative to
> the CRS has been rotated but I'd be interested in how to handle both cases.
> Thanx!
> gaby
>
> Martin Desruisseaux wrote:
>> What is rotated exactly? The Coordinate Reference System (CRS)
>> "northing" relative to longitude lines, or the grid coverage relative to
>> the CRS? The rotation is handled differently in the two cases.
If a CRS is rotated relative to some other CRS, we can do the following:
AffineTransform rotation = AffineTransform.getRotateInstance(...);
// Note: In the above construction, you will probable need to consider
// the translation terms too if the rotation is performed around
// any other point than (0,0).
MathTransform transform = ProjectiveTransform.create(rotation);
OperationMethod method = new DefaultOperationMethod(transform);
CoordinateReferenceSystem originalCRS = ...
CoordinateReferenceSystem rotatedCRS = new DefaultDerivedCRS("some name",
method, originalCRS, transform, originalCRS.getCoordinateSystem());
If the grid is rotated relative to the CRS, create an AffineTransform that
represents the transformation from grid to CRS taking in account this rotation:
double scaleX = ...;
double scaleY = ...;
double translateX = ...;
double translateY = ...;
AffineTransform at = new AffineTransform(scaleX, 0, 0, scaleY, translateX,
translateY);
at.rotate(...);
MathTransform gridToCRS = ProjectiveTransform.create(at);
and now use the GridGeometryFactory.create(...) method that expect a
MathTransform argument instead of an Envelope.
Martin
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