[gdal-dev] ENVI Rotation Bug Fix

[Kurt Schwehr]

Warning... I did a cleanup pass and split out the class definitions into a
header to allow direct C++ testing.

https://trac.osgeo.org/gdal/changeset/37530
https://trac.osgeo.org/gdal/changeset/37514
https://trac.osgeo.org/gdal/changeset/37510

I haven't written that testing yet, but it will be similar to this:

https://github.com/schwehr/gdal-autotest2/blob/master/cpp/frmts/jp2kak/jp2kakdataset_test.cc

-kurt

On Wed, Mar 1, 2017 at 2:56 AM, Damian Dixon <damian.dixon at gmail.com> wrote:

> Hi Taylor,
>
> M_PI is defined pretty much everywhere. The only compiler that you have to
> jump through hoops to get it is Visual Studio where you have to define '#define
> _USE_MATH_DEFINES'.
>
> As Even has mentioned it's also defined in the GDAL portability header.
>
> The main reason the use of atan jumped out is that I've run into problems
> with atan on Intel CPUs and GPUs in the past. Also the use of trig' of any
> sort is expensive so I tend to take a look to see if it can be removed or
> moved.
>
> I spotted that this is a very old bug so I'm pleased that you've taken the
> time to fix it.
>
> Regards
> Damian
>
>
>
> On 27 February 2017 at 22:12, Brown, Taylor Alexander <
> browtayl at oregonstate.edu> 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.
>>
>>
>> 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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