[gdal-dev] Need some info on geotiff tags missing

[Andrea Peri]

thx Even for explanation.

Also I see the real important for some software is the presence of this section:

    Keyed_Information:
       GTRasterTypeGeoKey (Short,1): RasterPixelIsPoint
       End_Of_Keys.

It can have two possibl values:
RasterPixelIsPoint or RasterPixelIsArea

Seem that without a value for GTRasterTypeGeoKey some software don't work.

Is possible configure gdal to add this values when converting a
tif+tfw to a geotiff

?

Andrea.


2014-08-03 10:49 GMT+02:00 Even Rouault <even.rouault at mines-paris.org>:
> Le samedi 02 août 2014 23:48:54, Andrea Peri a écrit :
>> Hi,
>>
>> I have transform many old tiff+tfw rasters using this gdal transformation:
>>
>> gdal_translate -ot Byte -of GTiff -b 1 -a_nodata none -stats -co
>> COMPRESS=NONE -co INTERLEAVE=PIXEL -co PROFILE=GDALGeoTIFF -co
>> TILED=YES -co BLOCKXSIZE=256 -co BLOCKYSIZE=256 -co SPARSE_OK=TRUE -co
>> TFW=NO filein.tif fileout.tif
>>
>> They are wrking correctly with qgis and with mapserver for several months.
>>
>> Now I need to use this geotiffs with another program.
>> But this program say that these images are not realy GeoTiffs.
>>
>> I test them using listgeos and have this result:
>>
>> TIFFReadDirectory: Warning, Unknown field with tag 42112 (0xa480)
>> encountered. Geotiff_Information:
>>    Version: 1
>>    Key_Revision: 1.0
>>    Tagged_Information:
>>       ModelTiepointTag (2,3):
>>          0                0                0
>>          559417.445637    4927786.430528   0
>>       ModelPixelScaleTag (1,3):
>>          0.5              0.5              0
>>       End_Of_Tags.
>>    Keyed_Information:
>>       End_Of_Keys.
>>    End_Of_Geotiff.
>>
>> Some people say me that this is not a true geotiff because are missing
>> several tags.
>> I reported a supposed response from a real geotiff:
>>
>> Geotiff_Information:
>>     Version: 1
>>     Key_Revision: 1.0
>>     Tagged_Information:
>>        ModelTiepointTag (2,3):
>>           0                 0                 0
>>           673347            4298291           0
>>        ModelPixelScaleTag (1,3):
>>           1                 1                 1
>>        End_Of_Tags.
>>     Keyed_Information:
>>        GTModelTypeGeoKey (Short,1): ModelTypeProjected
>>        GTRasterTypeGeoKey (Short,1): RasterPixelIsArea
>>        GTCitationGeoKey (Ascii,37): "NAIP 2012
>> m_3808409_sw_16_1_20120607"
>>        ProjectedCSTypeGeoKey (Short,1): PCS_NAD83_UTM_zone_16N
>>        PCSCitationGeoKey (Ascii,21): "NAD83 / UTM zone 16N"
>>        ProjLinearUnitsGeoKey (Short,1): Linear_Meter
>>        End_Of_Keys.
>>     End_Of_Geotiff.
>>
>> PCS = 26916 (NAD83 / UTM zone 16N)
>> Projection = 16016 (UTM zone 16N)
>> Projection Method: CT_TransverseMercator
>>     ProjNatOriginLatGeoKey: 0.000000 (  0d 0' 0.00"N)
>>     ProjNatOriginLongGeoKey: -87.000000 ( 87d 0' 0.00"W)
>>     ProjScaleAtNatOriginGeoKey: 0.999600
>>     ProjFalseEastingGeoKey: 500000.000000 m
>>     ProjFalseNorthingGeoKey: 0.000000 m
>> GCS: 4269/NAD83
>> Datum: 6269/North American Datum 1983
>> Ellipsoid: 7019/GRS 1980 (6378137.00,6356752.31)
>> Prime Meridian: 8901/Greenwich (0.000000/  0d 0' 0.00"E)
>> Projection Linear Units: 9001/metre (1.000000m)
>>
>> Corner Coordinates:
>> Upper Left    (  673347.000, 4298291.000)  ( 85d 0'12.06"W,
>> 38d48'58.87"N)
>> Lower Left    (  673347.000, 4290632.000)  ( 85d 0'18.99"W,
>> 38d44'50.54"N)
>> Upper Right   (  679532.000, 4298291.000)  ( 84d55'55.75"W,
>> 38d48'54.41"N)
>> Lower Right   (  679532.000, 4290632.000)  ( 84d56' 2.92"W,
>> 38d44'46.10"N)
>> Center        (  676439.500, 4294461.500)  ( 84d58' 7.43"W,
>> 38d46'52.50"N)
>>
>> -----
>>
>> I'm a bit confused.
>> Because I have produced my GeoTiffs using gdal. And if it fail to
>> produce a real geotiff I have a trouble.
>>
>> So the main question is a geotiff ith only the tags reported a real geotiff
>> ?
>
> Andrea,
>
> The difference between the 2 geotiff is that the first one does not have
> information on the spatial reference system, but only the geotransform that
> comes from the .tfw file.
> Skimming quickly through the GeoTIFF specification (
> http://www.remotesensing.org/geotiff/spec/contents.html ) doesn't immediately
> show if it is valid or not, although it would be best if readers are robust to
> missing information.
> If you know the SRS of the maps, you can try adding -a_srs EPSG:XXXX or -a_srs
> wkt_string.
> You could also try -a_srs "LOCAL_CS[\"Unknown\"]" if you don't know the SRS at
> all. This will write a few geotiff keys to define a unknown CRS, but it is not
> obvious that your reader will like it.
>
> Even
>
> --
> Geospatial professional services
> http://even.rouault.free.fr/services.html



-- 
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Andrea Peri
. . . . . . . . .
qwerty àèìòù
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