Keep in mind that Jon said that the code now correctly implements the 1.3
standard, not that the standard makes any sense. Interpreting 'x' and 'y'
as 'the order one prints the pair of coordinates in' was an extremely poor
choice by the committee, especially since it was different in 1.1. To use
1.3 correctly, the code has to know what order the coordinates are for each
projection, more or less impossible to code without a kludge or a
projection database standard API.
On Mon, Apr 15, 2013 at 3:32 PM, John Maurer <jmaurer@xxxxxxxxxx> wrote:
> Thanks, all! I'm surprised the ordering of coordinates changes with
> projection, but I can work with that! I appreciate your responses.
> Cheers,
> John (Maurer)
>
>
> On Mon, Apr 15, 2013 at 12:01 AM, Jon Blower <j.d.blower@xxxxxxxxxxxxx>wrote:
>
>> **Ø **for some unfathomable reason the spec switches to
>> ymin,xmin,ymax,xmax in 1.3.0 when you use CRS:84****
>>
>> ** **
>>
>> I think you mean “… when you use EPSG:4326”. CRS:84 is always x,y axis
>> order. ;-)****
>>
>> ** **
>>
>> The reason is that the EPSG database uses conventions from navigation,
>> which is latitude-longitude order. There was a mistake in WMS1.1.1 that
>> meant that EPSG:4326 was defined with the axis order reversed. This was
>> corrected in WMS 1.3.0 and a new CRS added (CRS:84) that is defined with
>> longitude-latitude axis order.****
>>
>> ** **
>>
>> Thanks for those links Ivan, very helpful!****
>>
>> ** **
>>
>> Jon****
>>
>> ** **
>>
>> *From:* Ivan Price [mailto:Ivan.Price@xxxxxxxxxxx]
>> *Sent:* 15 April 2013 10:18
>> *To:* John Maurer; THREDDS Users; ncwms-users@xxxxxxxxxxxxxxxxxxxxx
>> *Subject:* Re: [Ncwms-users] [thredds] WMS 1.3.0 blank maps using
>> EPSG:4326 (but works using CRS:84)****
>>
>> ** **
>>
>> it could be the order of lat/longs is reversed in your request.****
>>
>> ** **
>>
>> for some unfathomable reason the spec switches to ymin,xmin,ymax,xmax in
>> 1.3.0 when you use CRS:84****
>>
>> ** **
>>
>> see this:****
>>
>>
>> http://viswaug.wordpress.com/2009/03/15/reversed-co-ordinate-axis-order-for-epsg4326-vs-crs84-when-requesting-wms-130-images/
>> ****
>>
>> ** **
>>
>> or ncWMS specifically this:****
>>
>> ** **
>>
>>
>> http://www.resc.rdg.ac.uk/trac/ncWMS/wiki/FrequentlyAskedQuestions#MyWMSclientuseslatitude-longitudeaxisorder
>> ****
>>
>> ** **
>>
>> so your initial link works if you swap them around...****
>>
>> ** **
>>
>>
>> http://oos.soest.hawaii.edu/thredds/wms/hioos/roms_forec_regridded/hiig/ROMS_Hawaii_Regional_Ocean_Model_Regridded_best.ncd?service=WMS&version=1.3.0&REQUEST=GetMap&FORMAT=image/png&TRANSPARENT=true&LAYERS=water_temp&CRS=EPSG:4326&BBOX=20.17714549791179,202.12371826171875,21.50418550077842,204.46517944335938&WIDTH=1705&HEIGHT=1034&TIME=2013-04-15T00:00:00Z&ELEVATION=-5&STYLES=boxfill/rainbow&NUMCOLORBANDS=256&COLORSCALERANGE=24.02441,26.03417
>> ****
>>
>> ** **
>>
>> ** **
>>
>> -i****
>>
>> ** **
>>
>> ** **
>>
>> ** **
>>
>> *De :* thredds-bounces@xxxxxxxxxxxxxxxx [
>> mailto:thredds-bounces@xxxxxxxxxxxxxxxx<thredds-bounces@xxxxxxxxxxxxxxxx>]
>> *De la part de* John Maurer
>> *Envoyé :* Saturday, 13 April 2013 02:46
>> *À :* THREDDS Users; ncwms-users@xxxxxxxxxxxxxxxxxxxxx
>> *Objet :* [thredds] WMS 1.3.0 blank maps using EPSG:4326 (but works
>> using CRS:84)****
>>
>> ** **
>>
>> Hi TDS and/or ncWMS folks,
>> I recently upgraded from TDS 4.2.10 to 4.3.16 and am noticing something
>> strange in my WMS output. GetMap URL's that used to work fine in TDS 4.2.10
>> are coming up blank in 4.3.16. As a workaround, I discovered that changing
>> my CRS from EPSG:4326 to CRS:84 fixes the problem. Seems like a bug with
>> using EPSG:4326??
>>
>> Here's an example using a ROMS ocean forecast of water temperature over
>> central Hawaii. Using EPSG:4326 gives a blank map:
>>
>>
>> http://oos.soest.hawaii.edu/thredds/wms/hioos/roms_forec_regridded/hiig/ROMS_Hawaii_Regional_Ocean_Model_Regridded_best.ncd?service=WMS&version=1.3.0&REQUEST=GetMap&FORMAT=image/png&TRANSPARENT=true&LAYERS=water_temp&CRS=EPSG:4326&BBOX=202.12371826171875,20.17714549791179,204.46517944335938,21.50418550077842&WIDTH=1705&HEIGHT=1034&TIME=2013-04-15T00:00:00Z&ELEVATION=-5&STYLES=boxfill/rainbow&NUMCOLORBANDS=256&COLORSCALERANGE=24.02441,26.03417
>>
>> In contrast, if I switch this to CRS:84 I now get a color map as expected:
>>
>>
>> http://oos.soest.hawaii.edu/thredds/wms/hioos/roms_forec_regridded/hiig/ROMS_Hawaii_Regional_Ocean_Model_Regridded_best.ncd?service=WMS&version=1.3.0&REQUEST=GetMap&FORMAT=image/png&TRANSPARENT=true&LAYERS=water_temp&CRS=CRS:84&BBOX=202.12371826171875,20.17714549791179,204.46517944335938,21.50418550077842&WIDTH=1705&HEIGHT=1034&TIME=2013-04-15T00:00:00Z&ELEVATION=-5&STYLES=boxfill/rainbow&NUMCOLORBANDS=256&COLORSCALERANGE=24.02441,26.03417
>>
>> Oh... And I just found another workaround. If I switch to WMS 1.1.1
>> instead of 1.3.0, EPSG:4326 also works:
>>
>>
>> http://oos.soest.hawaii.edu/thredds/wms/hioos/roms_forec_regridded/hiig/ROMS_Hawaii_Regional_Ocean_Model_Regridded_best.ncd?service=WMS&version=1.1.1&REQUEST=GetMap&FORMAT=image/png&TRANSPARENT=true&LAYERS=water_temp&SRS=EPSG:4326&BBOX=202.12371826171875,20.17714549791179,204.46517944335938,21.50418550077842&WIDTH=1705&HEIGHT=1034&TIME=2013-04-15T00:00:00Z&ELEVATION=-5&STYLES=boxfill/rainbow&NUMCOLORBANDS=256&COLORSCALERANGE=24.02441,26.03417
>>
>> In short, I'm hoping that somebody can fix the WMS so that EPSG:4326 will
>> not give me blank maps in WMS 1.3.0, but I have workarounds in the meantime
>> so it's not pressing.
>> Thanks!,
>> John Maurer
>> Pacific Islands Ocean Observing System (PacIOOS)
>> University of Hawaii at Manoa****
>>
>
>
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--
Dr. M. Benno Blumenthal benno@xxxxxxxxxxxxxxxx
International Research Institute for climate and society
The Earth Institute at Columbia University
Lamont Campus, Palisades NY 10964-8000 (845) 680-4450
