[Geoserver-users] CRS84, EPSG4326, and min/max x/y

GeoServer GeoServer User
1

Hi List,
While browsing public services, I came across a public GeoServer instance (v2.9.1) that has this in its WMS GetCapabilities:

EPSG:4326CRS:84
<EX_GeographicBoundingBox>-180.0000036180.0000036-90.0000018-59.9999988</EX_GeographicBoundingBox>

<BoundingBox CRS=“CRS:84” minx=“-180.0000036” miny=“-90.0000018” maxx=“180.0000036” maxy=“-59.9999988”/>

The CRS:84 that’s advertised has an invalid minx/maxx.

I know that EPSG:4326 and CRS:84 are the same except 4326 is lat/lon, and 84 is lon/lat, but why is GeoServer swapping the CRS:84 values around for explicit x/y statements?

Cheers,
Jonathan

2

Hi,

What do you mean with “explicit x/y statements?”

Here is an excerpt from the WMS 1.3.0 standard, section 6.7.4:

EXAMPLE 1 A metadata element for a Layer representing the entire Earth in the CRS:84 Layer CRS

would be written as

.

A BBOX parameter requesting a map of the entire Earth would be written in this CRS as

BBOX=-180,-90,180,90.

EXAMPLE 2 A representing the entire Earth in the EPSG:4326 Layer CRS would be written as

.

A BBOX parameter requesting a map of the entire Earth would be written in this CRS as

BBOX=-90,-180,90,180.

For me it seems that Geoserver follows the standard literally.

-Jukka Rahkonen-

···

Lähettäjä: Jonathan Moules [mailto:jonathan-lists@…7221…]
Lähetetty: 10. joulukuuta 2017 20:57
Vastaanottaja: geoserver-users@lists.sourceforge.net
Aihe: [Geoserver-users] CRS84, EPSG4326, and min/max x/y

Hi List,
While browsing public services, I came across a public GeoServer instance (v2.9.1) that has this in its WMS GetCapabilities:

EPSG:4326CRS:84
<EX_GeographicBoundingBox>-180.0000036180.0000036-90.0000018-59.9999988</EX_GeographicBoundingBox>

<BoundingBox CRS=“CRS:84” minx=“-180.0000036” miny=“-90.0000018” maxx=“180.0000036” maxy=“-59.9999988”/>

The CRS:84 that’s advertised has an invalid minx/maxx.

I know that EPSG:4326 and CRS:84 are the same except 4326 is lat/lon, and 84 is lon/lat, but why is GeoServer swapping the CRS:84 values around for explicit x/y statements?

Cheers,
Jonathan

3

Hi Jukka,
It doesn’t help that I bolded the wrong part. It should have been the miny and maxy for EPSG:4326:

<BoundingBox CRS=“EPSG:4326” minx=“-90.0000018” miny=“-180.0000036” maxx=“-59.9999988” maxy=“180.0000036”/>

Because convention suggests that miny/maxy can’t be above (-)90 but that is indeed what the WMS specification says. I was hoping they’d learnt from the switching lat/lon and lon/lat fiasco. Flipping the X and Y axis like that is just… wrong. Another edge case to try and remember.

Thanks for the spot. GeoServer is indeed implementing the standard.
Cheers,
Jonathan

---- On Mon, 11 Dec 2017 13:24:46 +0000 Rahkonen Jukka (MML)jukka.rahkonen@anonymised.com wrote ----

Hi,

What do you mean with “explicit x/y statements?”

Here is an excerpt from the WMS 1.3.0 standard, section 6.7.4:

EXAMPLE 1 A metadata element for a Layer representing the entire Earth in the CRS:84 Layer CRS

would be written as

.

A BBOX parameter requesting a map of the entire Earth would be written in this CRS as

BBOX=-180,-90,180,90.

EXAMPLE 2 A representing the entire Earth in the EPSG:4326 Layer CRS would be written as

.

A BBOX parameter requesting a map of the entire Earth would be written in this CRS as

BBOX=-90,-180,90,180.

For me it seems that Geoserver follows the standard literally.

-Jukka Rahkonen-

Lähettäjä: Jonathan Moules [mailto:jonathan-lists@anonymised.com]
Lähetetty: 10. joulukuuta 2017 20:57
Vastaanottaja: geoserver-users@lists.sourceforge.net
Aihe: [Geoserver-users] CRS84, EPSG4326, and min/max x/y

Hi List,
While browsing public services, I came across a public GeoServer instance (v2.9.1) that has this in its WMS GetCapabilities:

EPSG:4326CRS:84
<EX_GeographicBoundingBox>-180.0000036180.0000036-90.0000018-59.9999988</EX_GeographicBoundingBox>

<BoundingBox CRS=“CRS:84” minx=“-180.0000036” miny=“-90.0000018” maxx=“180.0000036” maxy=“-59.9999988”/>

The CRS:84 that’s advertised has an invalid minx/maxx.

I know that EPSG:4326 and CRS:84 are the same except 4326 is lat/lon, and 84 is lon/lat, but why is GeoServer swapping the CRS:84 values around for explicit x/y statements?

Cheers,
Jonathan

4

I think in this instance x just means 1st axis and y means 2nd axis.

Ian

···

On 11 Dec 2017 16:57, “Jonathan Moules” <jonathan-lists@anonymised.com> wrote:

Hi Jukka,
It doesn’t help that I bolded the wrong part. It should have been the miny and maxy for EPSG:4326:

<BoundingBox CRS=“EPSG:4326” minx=“-90.0000018” miny=“-180.0000036” maxx=“-59.9999988” maxy=“180.0000036”/>

Because convention suggests that miny/maxy can’t be above (-)90 but that is indeed what the WMS specification says. I was hoping they’d learnt from the switching lat/lon and lon/lat fiasco. Flipping the X and Y axis like that is just… wrong. Another edge case to try and remember.

Thanks for the spot. GeoServer is indeed implementing the standard.
Cheers,
Jonathan

---- On Mon, 11 Dec 2017 13:24:46 +0000 Rahkonen Jukka (MML)<jukka.rahkonen@maanmittauslaitos.fi> wrote ----

Hi,

What do you mean with “explicit x/y statements?”

Here is an excerpt from the WMS 1.3.0 standard, section 6.7.4:

EXAMPLE 1 A metadata element for a Layer representing the entire Earth in the CRS:84 Layer CRS

would be written as

.

A BBOX parameter requesting a map of the entire Earth would be written in this CRS as

BBOX=-180,-90,180,90.

EXAMPLE 2 A representing the entire Earth in the EPSG:4326 Layer CRS would be written as

.

A BBOX parameter requesting a map of the entire Earth would be written in this CRS as

BBOX=-90,-180,90,180.

For me it seems that Geoserver follows the standard literally.

-Jukka Rahkonen-

Lähettäjä: Jonathan Moules [mailto:jonathan-lists@lightpear.com]
Lähetetty: 10. joulukuuta 2017 20:57
Vastaanottaja: geoserver-users@anonymised.comsourceforge.net
Aihe: [Geoserver-users] CRS84, EPSG4326, and min/max x/y

Hi List,
While browsing public services, I came across a public GeoServer instance (v2.9.1) that has this in its WMS GetCapabilities:

EPSG:4326CRS:84
<EX_GeographicBoundingBox>-180.0000036180.0000036-90.0000018-59.9999988</EX_GeographicBoundingBox>

<BoundingBox CRS=“CRS:84” minx=“-180.0000036” miny=“-90.0000018” maxx=“180.0000036” maxy=“-59.9999988”/>

The CRS:84 that’s advertised has an invalid minx/maxx.

I know that EPSG:4326 and CRS:84 are the same except 4326 is lat/lon, and 84 is lon/lat, but why is GeoServer swapping the CRS:84 values around for explicit x/y statements?

Cheers,
Jonathan

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