[MetaCRS] Use 2012 NGS geoid as default NAVD88 grids?

[Howard Butler]

All,

A new version of the NGS Geoid has been issued as of September 11th, 2012[1]. libgeotiff and cousins (GDAL when embedding libgeotiff) have been up until now defaulting to the 2003 NGS geoid as a default [2] if it is available via GTX file (fetched from http://download.osgeo.org/proj/vdatum/).

I would like to update libgeotiff and GDAL to use the 2012 grids by default (fetched from the same place) instead of the 2003 ones if they are available.

Does anyone see significant complications with this? You can continue to override your own grid files via WKT using the  EXTENSION["PROJ4_GRIDS","g2003conus.gtx,g2003alaska.gtx,g2003h01.gtx,g2003p01.gtx"]] mechanism, though that's probably only supported by GDAL right now.

Thanks,

Howard 

[1] http://www.ngs.noaa.gov/GEOID/
[2] http://trac.osgeo.org/metacrs/browser/geotiff/trunk/libgeotiff/csv/vertcs.override.csv#L11