[PROJ] Geo TIFF non-ASCII encodings

[Mircea Neacsu]

Hi,


> Anyway this would be more a topic for an issue at 
> https://github.com/opengeospatial/geotiff/issues . I've added a note 
> to the existing 
> https://github.com/opengeospatial/geotiff/issues/56#issuecomment-2039505940
Understood, but before jumping there with my opinionated ideas, let me 
point out that the root of the problem is the TIFF6.0 standard that 
continues to define field type 2 as ASCII. Their exact wording is: 
"8-bit byte that contains a 7-bit ASCII code; the last byte must be NUL 
(binary zero)" (page 15)

IMO everything would work just fine if this would be replaced with 
"8-bit byte that contains UTF8 code units; the last byte must be NUL 
(binary zero)". Given that UTF-8 is an extension of ASCII, backwards 
compatibility wouldn't be so bad.

Mircea Neacsu

On 4/5/2024 6:59 AM, Even Rouault wrote:

> Hi,
>
> OGC GeoTIFF mostly formalizes the historical GeoTIFF 1.0 specification 
> from 1995, and UTF-8 at that time was still in its youth years. Not to 
> be mentioned that GeoTIFF was initially developed by NASA' JPL, so I 
> assume ASCII was good enough at that time for their purpose. As far as 
> I can see all EPSG CRS names as currently only use ASCII. It is true 
> though that WKT CRS potentially allows for more than ASCII for CRS 
> name, but only in the Latin1 character set.
>
> Anyway this would be more a topic for an issue at 
> https://github.com/opengeospatial/geotiff/issues . I've added a note 
> to the existing 
> https://github.com/opengeospatial/geotiff/issues/56#issuecomment-2039505940
>
> Even
>
> Le 05/04/2024 à 12:44, Mircea Neacsu via PROJ a écrit :
>> Hello,
>>
>> I had to read a bit deeper the Geo TIFF 1.1 standard and I was quite 
>> surprised to see that in doesn't allow any character representation 
>> outside the 7-bit ASCII text. Am I missing something?
>>
>> In particular CitationGeoKeys that are mandatory in certain cases do 
>> not allow for anything other than ASCII text. Seems a bit strange for 
>> an international standard.
>>
>> -- 
>>
>> Mircea Neacsu
>>
>>
>>
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> -- 
> http://www.spatialys.com
> My software is free, but my time generally not.
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