[Qgis-developer] Re: EPSG:2180 not recognised, although present in srs.db

[Richard Duivenvoorde]

FYI: after a short chat with FrankW I added to trac the following 
request: https://trac.osgeo.org/qgis/ticket/1035
If that works, we hopefully keep in sync with proj and family.

Maciej, did you file your zero-ending scalefactor bug/comment in trac? 
Because it would be nice if this could be tackled/discussed at the same 
time.... Feel free to add it to the srs.db ticket.

Regards,

Richard Duivenvoorde

Maciej Sieczka wrote:
> Maciej Sieczka pisze:
>> I built QGIS (latest SVN trunk) against an older PROJ 4.5.0 this time, 
>> and GDAL 1.4.4. Still no good. Below is the relevant debug output when 
>> loading the GeoTIFF. Looks like QGIS recognises the CS properly, but 
>> then fails to find a matching one in srs.sb. Any ideas what is the 
>> reason?
> 
> I think I know what is going on. Since GDAL 1.4.4 there is a change 
> [1],[2] that the scale factor k is treated as numeric instead of string 
> variable. This results in a following proj4 string for EPSG 2180 in GDAL 
>  > 1.4.2:
> 
> +proj=tmerc +lat_0=0 +lon_0=19 +k=0.9993 +x_0=500000 +y_0=-5300000 
> +ellps=GRS80 +units=m +no_defs
> 
> Whereas in QGIS srs.db, and GDAL =< 1.4.2 the same EPSG code is 
> represented with a slightly different proj4 string:
> 
> +proj=tmerc +lat_0=0 +lon_0=19 +k=0.999300 +x_0=500000 +y_0=-5300000 
> +ellps=GRS80 +units=m +no_defs
> 
> The difference in the number of zeros in k factor is enough for QGIS to 
> fail to recognize the SRS, if QGIS runs against GDAL 1.4.4 or later. I 
> verified that with the latest QGIS SVN trunk and GDAL 1.4.2, 1.4.4, 1.5.1.
> 
> Note that the problem is not limited to EPSG 2180. As can be seen in [1] 
> any SRS that uses k is affected. According to the epsg file shipped with 
> PROJ 4.5.0, this gives 1328 out of 6442 SRS definitions incompatible 
> between QGIS and GDAL > 1.4.2 [3].
> 
> Quite an issue. Can anything be done about it? Just trim ending zeros of 
> all k's in the srs.db? That would break comptibility between QGIS and 
> GDAL < 1.4.4. Considering that 1.4.4 was released over 4 months ago 
> maybe that would not be a big deal though?
> 
> [1]http://trac.osgeo.org/gdal/changeset/12625
> [2]http://trac.osgeo.org/gdal/ticket/1970
> [3]grep "\+k\=.*0" /usr/local/share/proj/epsg
> 
> Maciek
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