[gdal-dev] ENVI Rotation Bug Fix

Even Rouault even.rouault at spatialys.com
Mon Feb 27 04:33:46 PST 2017

On lundi 27 février 2017 03:55:54 CET Taylor Alexander Brown wrote:
> Greetings GDAL Community,
> I am developing an application [0] to process georeferenced raster
> hyperspectral imagery in ENVI format from NASA's Airborne
> Visual/Infrared Imaging Spectrometer (AVIRIS) [1].
> The `map info` section of the header files contain an undocumented [2]
> rotation field which is currently ignored by GDAL. As a result, the
> image is rotated incorrectly when I process it with `gdalwarp` or the
> GDAL Python API. Furthermore, the image is scaled incorrectly when I try
> to override the geotransform.
> I documented my experiences on the GIS Stack Exchange [3]. It has
> previously been described on the GDAL mailing list [4] and bug tracker
> [5]. I believe this issue also affects ASTER imagery [6][7].
> I have implemented a fix based off of branch `tags/2.1.3` and shared my
> code on GitHub [8]. It reads the `units` and `rotation` parameter from
> the `map info` section and uses these to calculate the geotransform. The
> scaling was off because the code expected the `units` parameter to be
> the last element in the list, when in my case it was the second to last.
> You can verify this behavior with the single-band image I have been
> using for testing [9].
> You are welcome to evaluate my code and contribute it back to the
> library. I am a novice at both GDAL and GIS, so there may well be
> problems. I would be willing to submit a pull request against your
> GitHub mirror if desired.

Yes, please issue a P.R. against the github mirror. Preferably against trunk which has more 
complete regression testing.


Spatialys - Geospatial professional services
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