[mapserver-dev] Axis order in WMS 1.3.0 (#3582)

[Martin Kofahl]

Hi -
here are the relevant parts from the WMS 1.3.0 specification, OpenGIS® Web Map Server Implementation Specification; OGC® 06-042; Copyright © 2006 Open Geospatial Consortium:

In 6.7.3 Layer CRS, 6.7.3.1 Introduction: "The Layer CRS has two axes, denoted x and y. The x axis is the first axis in the CRS definition, the y axis is the second axis. Depending on the particular CRS, the x axis may or may not be oriented West-to-East, and the y axis may or may not be oriented South-to-North." ...  "Coordinates shall be listed in the order defined by the CRS and shall be mapped appropriately to the Map CS i and j axes, swapping axis order as needed during the projection operation. Many projected coordinate reference systems have an axis and coordinate order other than easting, northing." *What I wonder about: "EPSG geographic coordinate reference systems follow ISO 6709 and always list latitude before longitude."*

In 6.7.4 Bounding boxes the same again: "The order in which ordinates in each pair are listed shall be as defined by the Layer CRS; x corresponds to the first axis in the Layer CRS and y to the second. This order may not coincide with the Map CS axis order i, j."

And in 7.3.3.6 BBOX a reference only: "... in the form "minx,miny,maxx,maxy". ... The units, ordering and direction of increment of the x and y axes are as defined by the Layer CRS (see 6.7.3)"


Another query on the epsg database - epsg codes in the 4xxx range with east/north orientation (according to the database there are 2475 codes with east/north and 1703 codes with north/east orientation):

4048	RGRDC 2005 / Congo TM zone 12
4049	RGRDC 2005 / Congo TM zone 14
4050	RGRDC 2005 / Congo TM zone 16
4051	RGRDC 2005 / Congo TM zone 18
4056	RGRDC 2005 / Congo TM zone 20
4057	RGRDC 2005 / Congo TM zone 22
4058	RGRDC 2005 / Congo TM zone 24
4059	RGRDC 2005 / Congo TM zone 26
4060	RGRDC 2005 / Congo TM zone 28
4061	RGRDC 2005 / UTM zone 33S
4062	RGRDC 2005 / UTM zone 34S
4063	RGRDC 2005 / UTM zone 35S
4071	Chua / UTM zone 23S
4082	REGCAN95 / UTM zone 27N
4083	REGCAN95 / UTM zone 28N
4087	WGS 84 / World Equidistant Cylindrical
4088	World Equidistant Cylindrical (Sphere)
4093	ETRS89 / DKTM1
4094	ETRS89 / DKTM2
4095	ETRS89 / DKTM3
4096	ETRS89 / DKTM4
4217	NAD83 / BLM 59N (ftUS)
4399	NAD27 / BLM 59N (ftUS)
4400	NAD27 / BLM 60N (ftUS)
4401	NAD27 / BLM 1N (ftUS)
4402	NAD27 / BLM 2N (ftUS)
4403	NAD27 / BLM 3N (ftUS)
4404	NAD27 / BLM 4N (ftUS)
4405	NAD27 / BLM 5N (ftUS)
4406	NAD27 / BLM 6N (ftUS)
4407	NAD27 / BLM 7N (ftUS)
4408	NAD27 / BLM 8N (ftUS)
4409	NAD27 / BLM 9N (ftUS)
4410	NAD27 / BLM 10N (ftUS)
4411	NAD27 / BLM 11N (ftUS)
4412	NAD27 / BLM 12N (ftUS)
4413	NAD27 / BLM 13N (ftUS)
4414	NAD83(HARN) / Guam Map Grid
4415	Katanga 1955 / Katanga Lambert
4418	NAD27 / BLM 18N (ftUS)
4419	NAD27 / BLM 19N (ftUS)
4420	NAD83 / BLM 60N (ftUS)
4421	NAD83 / BLM 1N (ftUS)
4422	NAD83 / BLM 2N (ftUS)
4423	NAD83 / BLM 3N (ftUS)
4424	NAD83 / BLM 4N (ftUS)
4425	NAD83 / BLM 5N (ftUS)
4426	NAD83 / BLM 6N (ftUS)
4427	NAD83 / BLM 7N (ftUS)
4428	NAD83 / BLM 8N (ftUS)
4429	NAD83 / BLM 9N (ftUS)
4430	NAD83 / BLM 10N (ftUS)
4431	NAD83 / BLM 11N (ftUS)
4432	NAD83 / BLM 12N (ftUS)
4433	NAD83 / BLM 13N (ftUS)
4437	NAD83(NSRS2007) / Puerto Rico and Virgin Is.
4438	NAD83 / BLM 18N (ftUS)
4439	NAD83 / BLM 19N (ftUS)
4455	NAD27 / Pennsylvania South
4456	NAD27 / New York Long Island
4457	NAD83 / South Dakota North (ftUS)
4462	WGS 84 / Australian Centre for Remote Sensing Lambert
4467	RGSPM06 / UTM zone 21N
4471	RGM04 / UTM zone 38S
4474	Cadastre 1997 / UTM zone 38S
4484	Mexican Datum of 1993 / UTM zone 11N
4485	Mexican Datum of 1993 / UTM zone 12N
4486	Mexican Datum of 1993 / UTM zone 13N
4487	Mexican Datum of 1993 / UTM zone 14N
4488	Mexican Datum of 1993 / UTM zone 15N
4489	Mexican Datum of 1993 / UTM zone 16N
4559	RRAF 1991 / UTM zone 20N
4647	ETRS89 / UTM zone N32
4826	WGS 84 / Cape Verde National

I think it's to late for the 6.0 release as this issue needs more investigation. But I'm pretty sure the current behavior of MapServer is not correct.

Best regards,
Martin