Optimize coordinate transformations in SARSensorModel

Summary

transformation between geographical coordinates and ECEF coordinates takes a lot of time in SarSensorModel computations. In the current implementation, a transform object is created for each transformation, this is very inefficient. Instead, the same transformation object can be created at class construction and used in each transformation.

Copyright

The copyright owner is CNES and has signed the ORFEO ToolBox Contributor License Agreement.

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