[GRASS-dev] Re: [GRASS GIS] #1536: add EPSG:900913 to location
wizard
GRASS GIS
trac at osgeo.org
Mon Jan 16 06:54:52 EST 2012
#1536: add EPSG:900913 to location wizard
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Reporter: timmie | Owner: grass-dev@…
Type: enhancement | Status: new
Priority: normal | Milestone: 6.4.2
Component: Projections/Datums | Version: 6.4.2 RCs
Keywords: google projection, epsg | Platform: MSWindows XP
Cpu: Unspecified |
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Changes (by hamish):
* keywords: => google projection, epsg
* type: defect => enhancement
Comment:
after originally reacting with horror, AFAIU the epsg people have given up
the fight and issued the spherical mercator with wgs84's major ellipsoid
radius its own epsg code. So this will be fixed in time with a new version
of the epsg file and the only action needed is to wait. it is not
recommended to use spherical merc for real analysis, only data transfer
and matching visual cartography.
it is designed to be very fast on their servers, not to seek the ultimate
perfection in geodesy. (fair enough for their needs)
I think g.proj works but it isn't listed in the wizard as the wizard just
parses the main epsg file while g.proj uses the PROJ4 library which also
checks the esri.extra file that contains the "Chris's funny" projection.
be careful calling it the 'google' projection, their google maps slippy
tile projection is a slightly different thing again (and even more
distorted). each row of tiles has its own slightly different projection!
the two are related but get confused a lot.
Hamish
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Ticket URL: <https://trac.osgeo.org/grass/ticket/1536#comment:1>
GRASS GIS <http://grass.osgeo.org>
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