[GRASS-user] Incorrect re-projection from EPSG:4326 to 3857

[Zhiyu (Drew) Li]

Hi there,

I just tried the same 4326 to 3857 re-projection with dockerized 7.5 trunk.
The results are correct.

Thanks so much!
Drew

On Thu, Jan 4, 2018 at 10:38 AM, Markus Neteler <neteler at osgeo.org> wrote:

> On Thu, Jan 4, 2018 at 6:25 PM, Markus Metz
> <markus.metz.giswork at gmail.com> wrote:
> > On Thu, Jan 4, 2018 at 9:08 AM, Helmut Kudrnovsky <hellik at web.de> wrote:
> >>
> >> Zhiyu (Drew) Li wrote
> >> > Hi there,
> >> >
> >> > I was trying to re-project a EPSG:4326 coordinate into EPSG:3857 using
> >> > GRASS, but I found GDAL gave me a different result.
> >> >
> >> > GRASS (7.2.2):
> ...
> > Regarding EPSG:3857:
> > Uses spherical development of ellipsoidal coordinates. Relative to WGS
> 84 /
> > World Mercator (CRS code 3395) errors of 0.7 percent in scale and
> > differences in northing of up to 43km in the map (equivalent to 21km on
> the
> > ground) may arise.
> >
> > This has been fixed in recent GRASS 7.4 and GRASS 7.5, providing same
> > results like GDAL.
>
> I have added a related note here for the upcoming 7.4.0 release:
>
> https://trac.osgeo.org/grass/wiki/Release/7.4.0-News#Projectionsupport
>
> markusN
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