[GRASSLIST:5460] Re: Problem: lat/long data across the 180 meridian

[Eric G. Miller]

On Tue, Feb 04, 2003 at 10:44:43AM +1300, Brent Wood wrote:
> 
> I have some seabed contours & some point (site) data east of New Zealand,
> covering both sides of the 180 deg meridian.
> 
> I set the region to
> 
> ellipsoid:  wgs84
> north:      42:16:48S
> south:      45:07:40.8S
> west:       172:02:45.6E
> east:       172:50:02.4W
> 
> The point data (ascii xyz imported into sites) has x values of -160 to 190
> (where 190 = -170 = 170W). GRASS only displays the data (in the monitor)
> in the Eastern (<180) hemisphere (west side of the map). Converting the
> sites to vectors allows all the points to display, both sides of 180.
> 
> Similarly, the vector contours (imported from a shapefile in mercator &
> reprojected to lat long) display fine in the monitor.
> 
> I have converted the contours to a raster (v.surf.rst) but the resulting
> raster map doesn't all display (just the base color of the minimum value)
> not any cells East of 180 (ie, in the western hemisphere).
> 
> Much of my work involves data crossing the 180 meridian using lat/long, so
> this functionality is critical for my use of GRASS.
> 
> If this is not a bug, is there a way to work with lat/long data/maps
> (site, raster/vector) seamlessly across 180?

These are bugs in the respective programs, AFAIK.  They need to call
G_adjust_easting() to fix up the easting.  I've confirmed this with
d.sites and fixed it in CVS for the 5.0 HEAD branch.

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