[PROJ] Fixing Old Code

[support at mnspoint.com]

Hi,

we just traced the TIF tags with our own tracer for GeoTIFF tags and 
built first an examiner program to see what is in those files. Then when 
noticing that at least some files used "just number" to ESRI/EPGS we had 
to add the database to fill those references. But as I said the system 
only works as long as nobody adds new definitions and uses references to 
them in GeoTIFF files. If I remember correctly there is a way to include 
the full definition in the TIF file but the reality seemed to be that 
most GeoTIFF files just had that "number" reference.

Most likely your CSV files have some database but is it the one that 
includes all what is needed will always be a question (one should at 
least be aware that the possibility exists that the conversion later 
falls due to missing information in the outdated definitions database).

So the transformations are only as good as the data included is. But 
most likely there is an error message that the reference is unknown if 
that happens?! But that definitely adds some work since one has to 
always make sure to include the most resent definitions with the 
package. And sure ESRI/EPSG gets updates all the time since that is why 
it is built like that in the first place.

So the GeoTFF file format standard is not good. (Referencing any 
projection-datum definition without fully defining and including it in 
the file should be forbidden. So to make the GeoTIFF file fully 
independent. Now it is not.)

Janne.

----------------------------------------------
Dan Crosby kirjoitti 2023-07-31 00:10:
> Hi Janne,
> 
> Yes we did have to include all the libgeotiff accompanying CSV files
> in our distribution to get ours sort-of functional. But using
> libgeotiff functions like GTIFImageToPCS and GTIFProj4ToLatLong should
> mean any transformations are as good as they can be. Right?
> 
> Dan
> 
> -----Original Message-----
> From: support at mnspoint.com <support at mnspoint.com>
> Sent: Sunday, 30 July 2023 23:30
> To: Dan Crosby <dan.crosby at lincolnagritech.co.nz>
> Cc: proj at lists.osgeo.org
> Subject: Re: [PROJ] Fixing Old Code
> 
> Hello,
> 
> we wrote a working GeoTIFF loader a few years ago using Proj4 library.
> 
> The worts problem with GeoTIFF format is that it uses relative links
> to EPSG or ESRI definitions just with a number!! AND if somebody adds
> new definitions LATER the original database cannot solve them
> anymore!! REAL IDIOTS!! They should have ALWAYS included the FULL
> definition instead of just the "number"!! That way the GeoTIFF format
> would have worked forever! Now it just works until somebody adds a new
> entry to the database and some other idiot chooses to reference it in
> a GeoTIFF file!
> 
> But what so ever, you can try to live with this error by always using
> the latest ESRI/EPSG database with your GeoTIFF loader! (So, your
> GeoTIFF loader needs an ESRI/EPSG definition database to work.)
> 
> Regards: Janne
> 
> ------------------------------------------
> Dan Crosby kirjoitti 2023-07-26 06:19:
>> 
>> One thing I tried to get working at the time, but never really did,
>> was to read to geo-data from a GeoTIFF and convert
>> 
>> steps I should take to get the correct projection info out of a
>> GeoTIFF and convert it?
>> 
>> Thanks,
>> 
>> Dan