ISIS3 scale_factor wrongly defaulting to 0 for Polar Stereographic

[thare]

ISIS3 does not explicitly define a scale_factor for the Polar Stereographic projection. During GDAL parsing, since nothing is found, the GDAL scale_factor is getting set to 0 (when it should default to 1).

I believe by adding ', "1.0" ' (I hope as a string) to the line below, it should correctly default to a scale_factor=1.0 when the keyword is not found in the label. Here is the corrected code which is about line 534 in isis3dataset.cpp

    /***********   Grab scaleFactor ************/
    scaleFactor = 
        atof(poDS->GetKeyword( "IsisCube.Mapping.scaleFactor", "1.0"));

Attached is thumbnail lunar image which can be used for testing. Simply running gdalinfo can be used to test to see if the scale_factor is correctly set to 1.

Lastly, it looks like the ISIS2 and PDS readers are already forcing the value correctly to 1 in the GDAL listed projection.

thanks, Trent

[thare]

ISIS3 file for polar testing

[warmerdam]

Corrected as suggested in trunk (r23929) and 1.9 branch (r23930).

I haven't actually tested it other than to build it. Let me know if a problem persists.