Re: [Matplotlib-users] Accessing WMS and ESRI REST services in Matplotlib

On 10/16/12 11:20 AM, Rich Signell wrote:
> Jeff,
> Yep, that worked!  So here is a working example of OWSlib with
> Basemap:  http://nbviewer.ipython.org/3900648/
>
> I switched the Basemap projection to 'cyl' because we need to ensure
> that Basemap and WMS are using the same projection, right?  (and since
> I had requested EPSG:4326 from WMS, that's the 'cyl' in Basemap).
>
> Thanks!
> Rich

Rich: I took your code and made it into a new example.

https://github.com/matplotlib/basemap/pull/84

I think it may be better not to try to create a wmsimage method, since  
OWSlib.wms.WebMapService is quite a complicated beast to wrap.

-Jeff
>
> On Tue, Oct 16, 2012 at 11:38 AM, Jeff Whitaker <js...@fa...> wrote:
>> On 10/16/12 8:48 AM, Rich Signell wrote:
>>> Klo & Jeff,
>>>
>>> I tried making a concrete example of using OWSlib with Basemap, but
>>> althought the WMS image looks good, the warpimage does not.
>>>
>>> http://nbviewer.ipython.org/3899690/
>>>
>>> Do you see where I went wrong?
>>>
>>> Thanks,
>>> Rich
>>
>> Rich:  warpimage assumes the image is of global extent.  In your example, I
>> think you can just pass the image to the basemap imshow method with
>>
>> from matplotlib.image import imread
>> import urllib2
>> m.imshow(imread(urllib2.urlopen(url)),origin='upper')
>>
>> Klo previously mentioned there might be a problem with the png data from the
>> WMS server being 'chunked', s you might have to use klo's imshow_chunked
>> function
>>
>> http://www.mail-archive.com/mat...@li.../msg25618.html
>>
>>
>> -Jeff
>>
>>> On Sat, Oct 13, 2012 at 7:26 PM, klo uo <kl...@gm...> wrote:
>>>> That's also what that snippet I linked does. You can add it to to Basemap
>>>> and it should work.
>>>>
>>>> However Jeff suggested we use this tiny package OWSlib and handle WMS
>>>> that
>>>> way, which is better IMHO, but for some reason we did not got further
>>>> reply.
>>>>
>>>>
>>>>
>>>> On Fri, Oct 12, 2012 at 1:31 PM, Rich Signell <rsi...@us...> wrote:
>>>>> WMS services are required to respond to  "GetCapabiltiies" request,
>>>>> reporting what layers, styles, times, elevations, and projections they
>>>>> have available.  So for example, using the Unidata WMS example below,
>>>>> if we do:
>>>>>
>>>>>
>>>>>
>>>>> http://motherlode.ucar.edu:8080/thredds/wms/fmrc/NCEP/NAM/CONUS_12km/NCEP-NAM-CONUS_12km-noaaport_best.ncd?service=WMS&request=GetCapabilities
>>>>>
>>>>> we can see from the XML response that the Coordinate Reference Systems
>>>>> supported are:
>>>>>
>>>>> <CRS>EPSG:4326</CRS>
>>>>> <CRS>CRS:84</CRS>
>>>>> <CRS>EPSG:41001</CRS>
>>>>> <CRS>EPSG:3857</CRS>
>>>>> <CRS>EPSG:27700</CRS>
>>>>> <CRS>EPSG:3408</CRS>
>>>>> <CRS>EPSG:3409</CRS>
>>>>> <CRS>EPSG:32661</CRS>
>>>>> <CRS>EPSG:32761</CRS>
>>>>>
>>>>> And for this server, the supported response types are:
>>>>> <Format>image/jpeg</Format>
>>>>> <Format>image/png</Format>
>>>>> <Format>application/vnd.google-earth.kmz</Format>
>>>>> <Format>image/gif</Format>
>>>>>
>>>>> So I guess one way to proceed if you wanted to use WMS in Matplotlib
>>>>> and avoid reprojection in python would be to:
>>>>> 1. do the WMS GetCapabilities request to find the available supported
>>>>> Coordinate Reference Systems (which will vary with WMS server)
>>>>> 2. setup Basemap to use one of these CRS
>>>>> 3. use the bounding box of your current axis (in projection units) as
>>>>> part of a GetMap request to the WMS.
>>>>>
>>>>> -Rich
>>>>>
>>>>> On Thu, Oct 11, 2012 at 12:16 AM, klo uo <kl...@gm...> wrote:
>>>>>> I guess that's it?
>>>>>>
>>>>>> warpimage() as it is now, checks if passed image is url, so we can add
>>>>>> additional check if image is url, with urlparse to deduce image
>>>>>> coordinates
>>>>>> and projection if present, then overlay it over already created Basemap
>>>>>> object.
>>>>>>
>>>>>>
>>>>>>
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>>>>>
>>>>> --
>>>>> Dr. Richard P. Signell   (508) 457-2229
>>>>> USGS, 384 Woods Hole Rd.
>>>>> Woods Hole, MA 02543-1598
>>>>
>>>
>
>