[gdal-dev] Problem saving/reading inf GCPs values in VRT

[Calogero Mauceri]

Il 5/26/2015 12:03 PM, Even Rouault ha scritto:
> Le mardi 26 mai 2015 11:40:22, Calogero Mauceri a écrit :
>> Il 5/26/2015 11:28 AM, Even Rouault ha scritto:
>>> Le mardi 26 mai 2015 11:00:21, Calogero Mauceri a écrit :
>>>> Hi all,
>>>>
>>>> we are having problems saving/reading GCPs values in a VRT file when
>>>> those values are inf or nan. This problem is happening on Window
>>>> platform while it is working as expected in unix systems.
>>>>
>>>> We are setting the GCP values in a VRT dataset using the library
>>>> function GDALSetGCPs. The inf values get saved into the VRT XML as
>>>> "*1.#INF00000000E+000*" string
>>>>
>>>> <GCPList Projection="PROJCS["unnamed",
>>>>
>>>>        GEOGCS["WGS 84",
>>>>        
>>>>            DATUM["WGS_1984",
>>>>            
>>>>                SPHEROID["WGS 84",6378137,298.257223563],
>>>>                TOWGS84[0,0,0,0,0,0,0]],
>>>>            
>>>>            PRIMEM["Greenwich",0],
>>>>
>>>> UNIT["degree",0.0174532925199433]],
>>>>
>>>>        PROJECTION["Orthographic"],
>>>>
>>>> PARAMETER["latitude_of_origin",71.331088221],
>>>> PARAMETER["central_meridian",-156.63420306],
>>>>
>>>>        PARAMETER["false_easting",0],
>>>>        PARAMETER["false_northing",0]]">
>>>>        <GCP Id="0" Pixel="0.0000" Line="0.0000" X="*1.#INF00000000E+000*"
>>>>
>>>> Y="*1.#INF00000000E+000*" />
>>>>
>>>>        <GCP Id="1" Pixel="363.0000" Line="0.0000"
>>>>        X="-3.463981152302E+004"
>>>>
>>>> Y="3.246591123662E+004" />
>>>>
>>>>        <GCP Id="2" Pixel="725.0000" Line="0.0000"
>>>>        X="-1.070555064325E+004"
>>>>
>>>> Y="1.097994383230E+004" />
>>>>
>>>>        <GCP Id="3" Pixel="1088.0000" Line="0.0000"
>>>>
>>>> X="-5.461709489401E+003" Y="6.277974169290E+003" />
>>>>
>>>>        <GCP Id="4" Pixel="1450.0000" Line="0.0000"
>>>>
>>>> X="-3.134437286904E+003" Y="4.191819043427E+003" />
>>>>
>>>>      </GCPList>
>>>>
>>>> when those values are read through the GDALGetGCPs library function,
>>>> then the inf values are set to 1.0.
>>>> Is this a bug in GDAL or are we setting the inf GCP values in the wrong
>>>> way?
>>>>
>>>> Note that on unix everything works fine, the inf values are saved as
>>>> "INF" strings in the VRT XML and they are properly converted when they
>>>> are read back.
>>> Calogero,
>>>
>>> Dealing with Inf or NaN serialized number on Windows require special
>>> cases. But I fail to see why you need to set GCPs at infinity or nan,
>>> and I'd bet the behaviour of the TPS or polynomial transforms will be
>>> pretty much undefined with such as value.
>>>
>>> Even
>> I agree with you Even, Inf and NaN values should not be saved as GCPs,
>> but the way how they are treated in GDAL is very misleading, as invalid
>> values become valid after saving and then reading them.
>> If you think that should not be fixed it
> Actually with changes done some time ago in trunk to use locale unaware
> functions to parse strings as double, it should have worked already, but only
> strict 1.#INF or -1.#INF were recognized. I've improved CPLStrodDelim() to
> also accept with other characters behind.
>
>> should be at least reported in
>> the documentation.
>>
>> Calogero

Great Even!
Will the changes be in next GDAL release?

Calogero

-- 
Calogero Mauceri
Software Engineer

Applied Coherent Technology Corporation (ACT)
www.actgate.com