GeoTIFF tags : projection parameters

[alexguyot]

Hi,

I'm experiencing an issue when exporting GeoTIFF in projection "Gauss-Kruger Slovenia" (Datum D-48 SLOVENIA).

When opening a GeoTIFF file that has been exported from GlobalMapper, I get the message shown on snapshot 1. The proposed projection parameters (snapshot 2) create an important shift between this exported GeoTIFF and the reference data. I therefore must manually force the projection to "Gauss-Kruger Slovenia" (Datum D-48 SLOVENIA).

Is it that the projection parameters written to the GeoTIFF tags are incorrects ?

A very useful option, would be to specify whether GeoTIFF tags related to the projection system should be written or not during export (such as GDAL would do when using option “PROFILE=BASELINE” (http://www.gdal.org/frmt_gtiff.html)) ?

Thanks in advance for your support.

Alex

[global_mapper]

Alex,

The problem is that there is not a defined EPSG code for the D-48 Slovenia datum, so when you export a GeoTIFF file using that datum no datum code is written to the file. If you check the option to also save a PRJ file when creating the GeoTIFF file then the datum from the PRJ file should be used when you load the GeoTIFF file.

I'm not sure that I understand the usefulness of writing a out a file without the GeoTIFF tags if known since compliant TIFF readers should just ignore them if they don't understand them.

Thanks,

Mike
Global Mapper Support
support@globalmapper.com

[global_mapper]

I was able to find an EPSG code for your entire projection definition (D48/GK), so I think I have a fix for this. I have placed a new build at http://www.globalmapper.com/global_mapper11.zip with the change for you to try. Simply download that file and extract the contents into your existing v11.xx installation folder to give it a try. If you are using the 64-bit version, there is a new build available at http://www.globalmapper.com/global_mapper11_64bit.zip .

Let me know if I can be of further assistance.

Thanks,

Mike
Global Mapper Support
support@globalmapper.com

[alexguyot]

Hi Mike,

Thanks for your feedback.

The export without GeoTIFF tags is a suggestion.

Because some parameters included in the TFW are redundant with some of the GeoTIFF tags, that might affect the consistency of a GeoTIFF package.

The option of prefering Word File coordinates instead of GeoTIFF tags coordinates is available at reading process ... a similar option would be usefull at writing process (at least for me ;-)

Thanks,
Alex