[TinyOWS-users] Inconsistent coordinate order with WFS 1.1.0 and srsName=EPSG:2393

[Rahkonen Jukka]

Olivier Courtin wrote:

On Sun, Aug 14, 2011 at 4:24 PM, Rahkonen Jukka
<Jukka.Rahkonen at mmmtike.fi> wrote:

Hi Jukka,

>> > 110A05 and 110A06 are eastern, so reverse axis either long or short srs.

>> > Something i've missed ?

>> The coordinates in the 110A05.out and 110A06.out files in the lonlat directory that I downloaded do not make
>> sense (not inside or close to Finland) if they are supposed to be in Northing-Easting order, which is correct for
>> EPSG:2393.
>> <gml:Point srsName="urn:ogc:def:crs:EPSG::2393"><gml:pos>3449686 7674378</gml:pos></gml:Point>

> It's suppose to be the same point than: 25.73408841497
> 69.1455073926807 expressed in EPSG:4326
> In fact i took the same point for UTM, lat/lon, and eastern spatial references.

> But indeed not sure that this point is or not in Finland.
> Does it really matter ?

I might, if the place is very far from the area where one of the coordinate systems is reasonable. No trouble in this case because point is in northern Finland and tranformation is for sure valid.

Here are the transformation results from cs2cs

Case 1
====
EPSG:2393. Notice, that usually Proj4 is missing the +towgs84 parameters and this will lead to some location error.
PostGIS by default has this error, but we do not need to care about it now.

C:\Program Files\FWTools2.4.7>cs2cs +proj=longlat +ellps=WGS84 +datum=WGS84 +no_
defs +to +proj=tmerc +lat_0=0 +lon_0=27 +k=1 +x_0=3500000 +y_0=0 +ellps=intl +to
wgs84=-96.0617,-82.4278,-121.7535,4.80107,0.34543,-1.37646,1.4964 +units=m
25.73408841497 69.1455073926807
3449861.19      7674309.69 -23.56

EPSG:2393 is X=North, Y=East system, so the correct output from WFS 1.0.0 is 3449861.19  7674309.69  but 7674309.69 3449861.19 from WFS 1.1.0

Cases 2 and 3
========
EPSG:3067 (ETRS-TM35FIN) and EPSG:32635 (WGS84 UTM 35N) are in practise synonyms and pleasant cases because their axis order is officially Easting-Northing.  

 C:\Program Files\FWTools2.4.7>cs2cs +proj=longlat +ellps=WGS84 +datum=WGS84 +no_
defs +to +init=epsg:3067
25.73408841497 69.1455073926807
449708.73       7671106.21 0.00

C:\Program Files\FWTools2.4.7>cs2cs +proj=longlat +ellps=WGS84 +datum=WGS84 +no_
defs +to +init=epsg:32635
25.73408841497 69.1455073926807
449708.73       7671106.21 0.00

Correct output from both EPSG:3067 and EPSG:32635 with both WFS 1.0.0 and WFS 1.1.0 would be 449708.73  7671106.21, which is just great and a reason to love these EPSG codes.

Case 4
====

EPSG:3047 is also almost the same as EPSG:3067 and EPSG:32635, but this system is officially Northing-Easting.
C:\Program Files\FWTools2.4.7>cs2cs +proj=longlat +ellps=WGS84 +datum=WGS84 +no_
defs +to +init=epsg:3047
25.73408841497 69.1455073926807
449708.73       7671106.21 0.00

Thus output from WFS 1.0.0 should be 449708.73  7671106.21 but reversed 7671106.21 449708.73 from WFS 1.1.0.


> The srtext of EPSG:3038-3051 contains
> AXIS["Easting",EAST],AXIS["Northing",NORTH],
> so they have the same behaviour than EPSG:2393.

So this srtext output for SRID 2393 means the same?
 AXIS["Y",EAST],AXIS["X",NORTH]

And AXIS["Easting",EAST],AXIS["Northing",NORTH] means the same as the report from EPSG-registry

http://www.epsg-registry.org/report.htm?type=selection&entity=urn:ogc:def:crs:EPSG::3047&reportDetail=long&style=urn:uuid:report-style:default-with-urn&style_name=OGP%20Default%20With%20Urn&title=ETRS-TM35
which is telling that first comes Northing and then Easting?

I am sorry is I am asking silly questions, but for me even after 15 years GIS experience these projection things do not feel very simple.

-Jukka Rahkonen-