[josm-dev] WMTS scales - proper definition of 1m along meridian

Wiktor Niesiobedzki osm at vink.pl
Sun Jul 5 21:13:50 UTC 2015


2015-07-04 22:33 GMT+02:00 Wiktor Niesiobedzki <osm at vink.pl>:
> 2015-07-02 23:57 GMT+02:00 Paul Hartmann <phaaurlt at gmail.com>:
>> On 02.07.2015 23:33, Wiktor Niesiobedzki wrote:
>>
>>
>> I think it should go into the data/epsg file. The normal epsg file for Proj4
>> contains this info, e.g.:
>> # ATS77 / UTM zone 19N
>> <2219> +proj=utm +zone=19 +a=6378135 +b=6356750.304921594 +units=m +no_defs
>> <>
>>
>> (The "+units=m" part)
>>
>> The format is explained here:
>> https://github.com/OSGeo/proj.4/wiki/GenParms
>
> Thank you very much. That was exactly what I need. I'll update the
> epsg file with definitions of units and to_meter, as well as add
> support for this values in CustomProjection.

Ok,

After more twiddling with WTMS I found some other challenge regarding
EPGS - natural coordinate order, examples:
4326  - Axes: latitude, longitude. Orientations: north, east
2180  - Axes: northing, easting (x,y). Orientations: north, east
3857  - Axes: easting, northing (X,Y). Orientations: east, north
31370 - Axes: easting, northing (X,Y). Orientations: east, north.

Those above are taken from:
http://www.epsg-registry.org/

As you can see, there are some projections, where coordinates are
switched, and some, when they are not. My guess is maybe this could be
defined by setting axes=neu or axes=enu, as described in proj.4

But I do not see this extensively used in proj.4/nad/epsg
(https://github.com/OSGeo/proj.4/blob/master/nad/epsg) - only 28
entries with wsu value.

Do you think that we can induce this value from some other information
from our epsg file, or shall I add this information to our projection
definition?

Cheers,

Wiktor



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