Aviso images with global longitudinal extent downloaded with MGET display "Warning, incosistent extent!" in ArcMap

[jjr8]

Additionally, they cannot be added to raster catalogs because of the same problem.

This is a regression caused by the solution to #511. To fix that problem, I shifted the raster's x coordinate 1/2 cell to the left. The left and right extents changed from (-20015086.796, 20015086.796) to (-20033619.2838, 19996554.3082). I left the center longitude of the Mercator projection at -180.0 (i.e. the proj4 string +proj=merc +R=6371000 +lon_0=180 +no_defs).

I assumed that ArcGIS would understand that this projection is symmetrical across the plane of the equator and accept the coordinates. I was wrong. ArcGIS requires that the coordinates fall strictly within the domain defined by projecting the west-most and east-most longitudes (0 and 360) to Mercator coordinates for that spheroid. That domain is (-20015086.796, 20015086.796) and the left-most coordinate was outside it, so Arc failed.

The solution is to change the center longitude of the projection to 179.83333333333333 and switch back to using (-20015086.796, 20015086.796) as the left and right extents.

I tested with that Arc 10 SP3 and it seemed to work. ArcMap no longer issued the inconsistent extent warning. When I added global data in WGS-1984 geographic projection (GSHHS, MODIS aqua chlorophyll) the data were correctly projected to the exact edges of the Aviso data. (There was the warning about coordinate system transformations, but that is expected due to the datum difference.) Finally, I was able to add the Aviso rasters to a raster catalog.

This fix will be released in MGET 0.8a35. An 0.8a33 or 0.8a34 installation can be patched by replacing the file Aviso.py with the one I will check in shortly.

[jjr8]

Fixed in r924, released in MGET 0.8a35.