BAG uncertainty NoData value should be 1000000, not 0

[jdvarner]

The NODATA value for the uncertainty in BAG files is being reported as 0. However, I think it should be set to 1000000.

There's some inconsistency in the documentation: From OpenNavSurf (​http://www.opennavsurf.org/papers/BAG_FSD_Release_1.5.1.pdf, page 11): "The *unknown* state for uncertainty is defined to be 0.0"

From IHO S-102 Format Standard (​http://www.iho.int/iho_pubs/standard/S-102/S-102_Ed1.0.0_Apr12.pdf, page 34): "The *undetermined* state for uncertainty is defined to be 1,000,000.0 (1.0e6)."

I've checked a sampling of BAGs that we archive here at NOAA/NGDC. All of them have 1000000 in the uncertainty band in areas with no data.

Thanks to Mike Wilburn from Esri for pointing out this issue.

[jef]

Please report this on ​GDAL TRAC