[gdal-dev] ENVI Rotation Bug Fix

[Taylor Alexander Brown]

I have pushed the requested changes to a pull request:
https://github.com/OSGeo/gdal/pull/197


Taylor

On 02/27/2017 02:20 PM, Even Rouault wrote:
> On lundi 27 février 2017 14:12:46 CET Brown, Taylor Alexander wrote:
> 
>> Damian,
> 
>>
> 
>> I agree that it would be preferable to use a predefined constant. However,
> 
>> I was under the impression that M_PI is a compiler extension and not part
> 
>> of standard C++, so I wanted to make sure it was compatible. If using M_PI
> 
>> is acceptable, I would be happy to change it. I will be submitting my pull
> 
>> request shortly.
> 
>  
> 
> M_PI is #define'd in port/cpl_port.h if not already defined.
> 
>  
> 
>>
> 
>>
> 
>> Taylor
> 
>>
> 
>> On Mon, Feb 27, 2017 at 5:01 AM, Damian Dixon <damian.dixon at gmail.com>
> 
>>
> 
>> wrote:
> 
>> > Hi Taylor,
> 
>> >
> 
>> > I'm just lurking on the mailing list myself.
> 
>> >
> 
>> > I had a look at the code changes, as this is one of the formats I'm
> 
>> > interested in, and one point springs out at me:
> 
>> >
> 
>> > const double PI = atan(1.0) * 4;
> 
>> >
> 
>> > I find this line potentially a confusing way to define PI, particularly
> 
>> > when you combine it with (PI/180) later.
> 
>> >
> 
>> > Personally I would use M_PI.
> 
>> >
> 
>> > Regards
> 
>> > Damian
> 
>> >
> 
>> >
> 
>> >
> 
>> > On 27 February 2017 at 11:55, Taylor Alexander Brown <
> 
>> >
> 
>> > browtayl at oregonstate.edu> 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.
> 
>> >>
> 
>> >>
> 
>> >> Peace,
> 
>> >>
> 
>> >> Taylor Alexander Brown
> 
>> >>
> 
>> >>
> 
>> >> [0] https://github.com/capstone-coal/pycoal
> 
>> >> [1] https://aviris.jpl.nasa.gov/
> 
>> >> [2] http://www.harrisgeospatial.com/docs/enviheaderfiles.html
> 
>> >> [3]
> 
>> >> http://gis.stackexchange.com/questions/229952/rotate-envi-hy
> 
>> >> perspectral-imagery-with-gdal
> 
>> >> [4] https://lists.osgeo.org/pipermail/gdal-dev/2013-January/035146.html
> 
>> >> [5] https://trac.osgeo.org/gdal/ticket/1778
> 
>> >> [6] http://yceo.yale.edu/opening-aster-files-envi
> 
>> >> [7] http://yceo.yale.edu/faq-page#t2n504
> 
>> >> [8]
> 
>> >> https://github.com/OSGeo/gdal/compare/tags/2.1.3...browtayl:
> 
>> >> fix-envi-rotation?expand=1
> 
>> >> [9] https://drive.google.com/open?id=0BxysdOuBmaIGalY5dVhCa1Y5M0k
> 
>> >> _______________________________________________
> 
>> >> gdal-dev mailing list
> 
>> >> gdal-dev at lists.osgeo.org
> 
>> >> https://lists.osgeo.org/mailman/listinfo/gdal-dev
> 
>  
> 
>  
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