Computing area in Mercator is only sensible over small regions. So it’s questionable even for 3857.
I was curious what the difference was between projections 3785 and 3857, and found this reference: http://forums.esri.com/Thread.asp?c=93&f=984&t=288607 “EPSG originally added 'Popular Visualisation CRS / Mercator' in March 2008 with code number 3785. That has now been deprecated and replaced with 3857, 'WGS 84 / Pseudo-Mercator'.” So it seems that any use of and reference to the former should be updated. Since a geographic coordinate system like WGS84 is the foundation for every projected coordinate system, and it’s a relatively simple process to convert from the former to the latter with open-source libraries, the question is if there are any programs that we need to support that don’t have projection ability and therefore require a particular projection as input. — Andy Anderson On Oct 16, 2014, at 12:24 PM, Andrew Buck <[email protected]> wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Having it be selectable would be a good solution. Paul Norman raised > an interesting point on the github issue that currently we are > currently adding a column of 'area' to the polygons table which can > only be computed sensibly if you are in a projection like 3857, if we > use wgs84 it would not make sense to have that column. > > Now, since the column is not really used anyway (as far as I know) and > since you can re-add the column yourself in GIS software, then I see > no reason not to just drop the column and make setting the projection > an option. > > - -AndrewBuck > > > On 10/16/2014 10:59 AM, Kate Chapman wrote: >> Hi All, >> >> There was a reason for the current system (though honestly I cant >> remember what). Can someone else remember why? >> >> Perhaps selecting the projection would be a better choice long term >> as a new feature for the export tool? >> >> Best, >> >> -Kate >> >> On Thu, Oct 16, 2014 at 4:22 AM, Fran Boon <[email protected]> >> wrote: >> >>> On 16 October 2014 12:18, Fred Moine <[email protected]> wrote: >>>> Hot export: for the shape (export) could we change the >>>> coordinate >>> reference >>>> system Rather than to have Popular Visualisation CRS/Mercator >>>> ID EPSG: 3785 >>> could >>>> we have WGS84 ID EPSG: 4326 >>> >>> This is logged as this issue here: >>> https://github.com/hotosm/hot-exports/issues/80 >>> >>> I would definitely support this proposal! >>> >>> F >>> >>> _______________________________________________ HOT mailing list >>> [email protected] >>> https://lists.openstreetmap.org/listinfo/hot >>> >> >> >> >> >> >> _______________________________________________ HOT mailing list >> [email protected] https://lists.openstreetmap.org/listinfo/hot >> > > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1.4.11 (GNU/Linux) > > iQIcBAEBAgAGBQJUP/EvAAoJEK7RwIfxHSXbMM0P/A7pI2fvnEtt1hfJlVY0Db++ > LpIZJZq0LL2MBoAYQIz+jfo5KR62XV9J0PnHiGQGQWlZ5CohLPaBOef3f79o6cDi > FKtvEECFL/9swOjCBa0luAbBTu83L1IbuMcTqj8np3T8740+tG8eGIFelK5qRaSj > nuqAr6LX9lKRGV5GrEqy5iSt8Q4eAJr7woWZbFLgIQ5u93oc/Yshn4jeIuBTubXA > 7AM5vMNtxiyjuJMn7hl1h/WfeF2q/pd3XmfYEyJFDjNdrYbChQRSWrAgoFB7jur2 > EC/IEkEJS3HIQyZGIMegFbWDK7QTXjiaTDrDySMRJflPVVkwYWwt5/adw6+VXXR2 > z1hkzs3bleRWTUopIH+XKFpfEd+U3cds4j+6dW8DS5GXbkHfFx3Ywu17FAqC7m59 > gJ6BCnJxUWLQvceHxSxpwcvuDnTO3jcDZN8AR620rCEWi0gBEQNvIYdXg9DIMWy6 > zqovqHoU4xhtsvpsvVn3V3t+OLZY/OceTu9nY9UU6ijFpQCxuZ7eLE0ExAOuzvAc > uzQLhuNPd2lu38NrAYs8QTNJ5aNgYmmPno9pa7UGyZGIE+Pb3SPJmXPaWfPb60mO > P8NxIHh2hc0Cl3Y4XCbkS49iU2v7NMOcUNhMRpaYiPmyCKPlGwFylvhu/bP5HP67 > UVHhhYvfCiigr87tfxH6 > =Bp+X > -----END PGP SIGNATURE----- > > _______________________________________________ > HOT mailing list > [email protected] > https://lists.openstreetmap.org/listinfo/hot _______________________________________________ HOT mailing list [email protected] https://lists.openstreetmap.org/listinfo/hot
