matplotlib-users

[Matplotlib-users] basemap UTM conversion discrepancy

[Stefan M. <in...@st...>]

Hello,

I'm starting to use the mpl_toolkits.basemap.pyproj.Proj class to do
lon/lat to UTM coordinate conversion.
I did some tests and noticed that there is a discrepancy between the
mpl_toolkits.basemap.pyproj.Proj output and the proj commandline tool
output.

e.g.: I'm converting the coordinates lat=48.2; lon=16.5 to UTM
coordinates UTM zone 33 with WGS84 ellipse.
I'm using the following proj4 string for the conversion:
+proj=utm +zone=33 +ellps=WGS84 +datum=WGS84 +units=m +no_defs

The output using mpl_toolkits.basemap.pyproj.Proj is:
x: 611458.865;  y: 5339596.032

The proj commandline tool using the same proj4 string gives:
x: 611458.69 y: 5339617.54

As you can see, the y coordinate differs significantly.

Here's the code used with the basemap pyproy classes:

--------------------------------------------------

from mpl_toolkits.basemap.pyproj import Proj

# I got the proj string from 
# http://spatialreference.org/ref/epsg/32633
myProj = Proj("+proj=utm +zone=33 +ellps=WGS84 +datum=WGS84 +units=m
+no_defs")

lat = 48.2
lon = 16.5

(x,y) = myProj(lon, lat)

print "x: %.3f; y: %.3f" % (x,y)

---------------------------------------------------

Can somebody explain me this behavior?

Regards,
   Stefan.

Re: [Matplotlib-users] basemap UTM conversion discrepancy

[Jeff W. <jef...@no...>]

On 12/19/11 2:23 PM, Stefan Mertl wrote:
> Hello,
>
> I'm starting to use the mpl_toolkits.basemap.pyproj.Proj class to do
> lon/lat to UTM coordinate conversion.
> I did some tests and noticed that there is a discrepancy between the
> mpl_toolkits.basemap.pyproj.Proj output and the proj commandline tool
> output.
>
> e.g.: I'm converting the coordinates lat=48.2; lon=16.5 to UTM
> coordinates UTM zone 33 with WGS84 ellipse.
> I'm using the following proj4 string for the conversion:
> +proj=utm +zone=33 +ellps=WGS84 +datum=WGS84 +units=m +no_defs
>
> The output using mpl_toolkits.basemap.pyproj.Proj is:
> x: 611458.865;  y: 5339596.032
>
> The proj commandline tool using the same proj4 string gives:
> x: 611458.69 y: 5339617.54
>
> As you can see, the y coordinate differs significantly.
>
> Here's the code used with the basemap pyproy classes:
>
> --------------------------------------------------
>
> from mpl_toolkits.basemap.pyproj import Proj
>
> # I got the proj string from
> # http://spatialreference.org/ref/epsg/32633
> myProj = Proj("+proj=utm +zone=33 +ellps=WGS84 +datum=WGS84 +units=m
> +no_defs")
>
> lat = 48.2
> lon = 16.5
>
> (x,y) = myProj(lon, lat)
>
> print "x: %.3f; y: %.3f" % (x,y)
>
> ---------------------------------------------------
>
> Can somebody explain me this behavior?
>
> Regards,
>     Stefan.
>
Stefan:

When I run this test, I get the same answer with both, and it is the 
same as the answer basemap.pyproj gave you.  I suspect you didn't 
install the extra datum files with your command-line proj distribution.

-Jeff

-- 
Jeffrey S. Whitaker         Phone  : (303)497-6313
Meteorologist               FAX    : (303)497-6449
NOAA/OAR/PSD  R/PSD1        Email  : Jef...@no...
325 Broadway                Office : Skaggs Research Cntr 1D-113
Boulder, CO, USA 80303-3328 Web    : http://tinyurl.com/5telg

Re: [Matplotlib-users] basemap UTM conversion discrepancy

[Stefan M. <in...@st...>]

Hi Jeff,

I'm not an expert in coordinate transformation and the usage of proj, so
I can't exactly tell you if I have all the datum files installed. If you
could tell me what files could be missing I could search for them.

What makes me wonder, is that you get the results that my
mpl_toolkits.basemap.pyproj.Proj usage produced. When using some
conversion tools on the internet like
http://home.hiwaay.net/~taylorc/toolbox/geodesy/datumtrans/ or
http://www.uwgb.edu/dutchs/UsefulData/ConvertUTMNoOZ.HTM
I get the results that my commandline proj produces.
So I think that something with my pyproj installation is not working.

Regards,
   Stefan.

Am Montag, den 19.12.2011, 15:51 -0700 schrieb Jeff Whitaker: 
> On 12/19/11 2:23 PM, Stefan Mertl wrote:
> > Hello,
> >
> > I'm starting to use the mpl_toolkits.basemap.pyproj.Proj class to do
> > lon/lat to UTM coordinate conversion.
> > I did some tests and noticed that there is a discrepancy between the
> > mpl_toolkits.basemap.pyproj.Proj output and the proj commandline tool
> > output.
> >
> > e.g.: I'm converting the coordinates lat=48.2; lon=16.5 to UTM
> > coordinates UTM zone 33 with WGS84 ellipse.
> > I'm using the following proj4 string for the conversion:
> > +proj=utm +zone=33 +ellps=WGS84 +datum=WGS84 +units=m +no_defs
> >
> > The output using mpl_toolkits.basemap.pyproj.Proj is:
> > x: 611458.865;  y: 5339596.032
> >
> > The proj commandline tool using the same proj4 string gives:
> > x: 611458.69 y: 5339617.54
> >
> > As you can see, the y coordinate differs significantly.
> >
> > Here's the code used with the basemap pyproy classes:
> >
> > --------------------------------------------------
> >
> > from mpl_toolkits.basemap.pyproj import Proj
> >
> > # I got the proj string from
> > # http://spatialreference.org/ref/epsg/32633
> > myProj = Proj("+proj=utm +zone=33 +ellps=WGS84 +datum=WGS84 +units=m
> > +no_defs")
> >
> > lat = 48.2
> > lon = 16.5
> >
> > (x,y) = myProj(lon, lat)
> >
> > print "x: %.3f; y: %.3f" % (x,y)
> >
> > ---------------------------------------------------
> >
> > Can somebody explain me this behavior?
> >
> > Regards,
> >     Stefan.
> >
> Stefan:
> 
> When I run this test, I get the same answer with both, and it is the 
> same as the answer basemap.pyproj gave you.  I suspect you didn't 
> install the extra datum files with your command-line proj distribution.
> 
> -Jeff
> 

Re: [Matplotlib-users] basemap UTM conversion discrepancy

[Jeff W. <js...@fa...>]

On 12/19/11 4:47 PM, Stefan Mertl wrote:
> Hi Jeff,
>
> I'm not an expert in coordinate transformation and the usage of proj, so
> I can't exactly tell you if I have all the datum files installed. If you
> could tell me what files could be missing I could search for them.
>
> What makes me wonder, is that you get the results that my
> mpl_toolkits.basemap.pyproj.Proj usage produced. When using some
> conversion tools on the internet like
> http://home.hiwaay.net/~taylorc/toolbox/geodesy/datumtrans/ or
> http://www.uwgb.edu/dutchs/UsefulData/ConvertUTMNoOZ.HTM
> I get the results that my commandline proj produces.
> So I think that something with my pyproj installation is not working.
>
> Regards,
>     Stefan.

Stefan: I mis-spoke in my earlier email - the answer I get with pyproj 
is the same as you get with command line proj.  What version of basemap 
do you have installed?

-Jeff
>
> Am Montag, den 19.12.2011, 15:51 -0700 schrieb Jeff Whitaker:
>> On 12/19/11 2:23 PM, Stefan Mertl wrote:
>>> Hello,
>>>
>>> I'm starting to use the mpl_toolkits.basemap.pyproj.Proj class to do
>>> lon/lat to UTM coordinate conversion.
>>> I did some tests and noticed that there is a discrepancy between the
>>> mpl_toolkits.basemap.pyproj.Proj output and the proj commandline tool
>>> output.
>>>
>>> e.g.: I'm converting the coordinates lat=48.2; lon=16.5 to UTM
>>> coordinates UTM zone 33 with WGS84 ellipse.
>>> I'm using the following proj4 string for the conversion:
>>> +proj=utm +zone=33 +ellps=WGS84 +datum=WGS84 +units=m +no_defs
>>>
>>> The output using mpl_toolkits.basemap.pyproj.Proj is:
>>> x: 611458.865;  y: 5339596.032
>>>
>>> The proj commandline tool using the same proj4 string gives:
>>> x: 611458.69 y: 5339617.54
>>>
>>> As you can see, the y coordinate differs significantly.
>>>
>>> Here's the code used with the basemap pyproy classes:
>>>
>>> --------------------------------------------------
>>>
>>> from mpl_toolkits.basemap.pyproj import Proj
>>>
>>> # I got the proj string from
>>> # http://spatialreference.org/ref/epsg/32633
>>> myProj = Proj("+proj=utm +zone=33 +ellps=WGS84 +datum=WGS84 +units=m
>>> +no_defs")
>>>
>>> lat = 48.2
>>> lon = 16.5
>>>
>>> (x,y) = myProj(lon, lat)
>>>
>>> print "x: %.3f; y: %.3f" % (x,y)
>>>
>>> ---------------------------------------------------
>>>
>>> Can somebody explain me this behavior?
>>>
>>> Regards,
>>>      Stefan.
>>>
>> Stefan:
>>
>> When I run this test, I get the same answer with both, and it is the
>> same as the answer basemap.pyproj gave you.  I suspect you didn't
>> install the extra datum files with your command-line proj distribution.
>>
>> -Jeff
>>
>>
>>
>> ------------------------------------------------------------------------------
>> Write once. Port to many.
>> Get the SDK and tools to simplify cross-platform app development. Create
>> new or port existing apps to sell to consumers worldwide. Explore the
>> Intel AppUpSM program developer opportunity. appdeveloper.intel.com/join
>> http://p.sf.net/sfu/intel-appdev
>>
>>
>> _______________________________________________
>> Matplotlib-users mailing list
>> Mat...@li...
>> https://lists.sourceforge.net/lists/listinfo/matplotlib-users

Re: [Matplotlib-users] basemap UTM conversion discrepancy

[Stefan M. <in...@st...>]

Jeff,

Here are the versions that I'm working with:
basemap:    1.0.2
matplotlib: 1.1.0
numpy:      1.5.1
libgeos:    3.2.0

I ran the coordinate conversion on another computer with the same system
configuration and there it works as it should.
I have tried to clean my system and removed all the packages related to
basemap (geos, proj) and only reinstalled the required libgeos packages.
I deleted the basemap directory from
the /usr/local/lib/python2.7/dist-packages.
I deleted the _geoslib.so from /usr/local/lib/python2.7/dist-packages.
After that I rebuilt and installed basemap.

The problem still remains.

Don't know what's going wrong.

Stefan.

Am Montag, den 19.12.2011, 18:33 -0700 schrieb Jeff Whitaker:
> On 12/19/11 4:47 PM, Stefan Mertl wrote: 
> > Hi Jeff,
> > 
> > I'm not an expert in coordinate transformation and the usage of proj, so
> > I can't exactly tell you if I have all the datum files installed. If you
> > could tell me what files could be missing I could search for them.
> > 
> > What makes me wonder, is that you get the results that my
> > mpl_toolkits.basemap.pyproj.Proj usage produced. When using some
> > conversion tools on the internet like
> > http://home.hiwaay.net/~taylorc/toolbox/geodesy/datumtrans/ or
> > http://www.uwgb.edu/dutchs/UsefulData/ConvertUTMNoOZ.HTM
> > I get the results that my commandline proj produces.
> > So I think that something with my pyproj installation is not working.
> > 
> > Regards,
> >    Stefan.
> 
> Stefan: I mis-spoke in my earlier email - the answer I get with pyproj
> is the same as you get with command line proj.  What version of
> basemap do you have installed?
> 
> -Jeff 
> > 
> > Am Montag, den 19.12.2011, 15:51 -0700 schrieb Jeff Whitaker: 
> > > On 12/19/11 2:23 PM, Stefan Mertl wrote:
> > > > Hello,
> > > > 
> > > > I'm starting to use the mpl_toolkits.basemap.pyproj.Proj class to do
> > > > lon/lat to UTM coordinate conversion.
> > > > I did some tests and noticed that there is a discrepancy between the
> > > > mpl_toolkits.basemap.pyproj.Proj output and the proj commandline tool
> > > > output.
> > > > 
> > > > e.g.: I'm converting the coordinates lat=48.2; lon=16.5 to UTM
> > > > coordinates UTM zone 33 with WGS84 ellipse.
> > > > I'm using the following proj4 string for the conversion:
> > > > +proj=utm +zone=33 +ellps=WGS84 +datum=WGS84 +units=m +no_defs
> > > > 
> > > > The output using mpl_toolkits.basemap.pyproj.Proj is:
> > > > x: 611458.865;  y: 5339596.032
> > > > 
> > > > The proj commandline tool using the same proj4 string gives:
> > > > x: 611458.69 y: 5339617.54
> > > > 
> > > > As you can see, the y coordinate differs significantly.
> > > > 
> > > > Here's the code used with the basemap pyproy classes:
> > > > 
> > > > --------------------------------------------------
> > > > 
> > > > from mpl_toolkits.basemap.pyproj import Proj
> > > > 
> > > > # I got the proj string from
> > > > # http://spatialreference.org/ref/epsg/32633
> > > > myProj = Proj("+proj=utm +zone=33 +ellps=WGS84 +datum=WGS84 +units=m
> > > > +no_defs")
> > > > 
> > > > lat = 48.2
> > > > lon = 16.5
> > > > 
> > > > (x,y) = myProj(lon, lat)
> > > > 
> > > > print "x: %.3f; y: %.3f" % (x,y)
> > > > 
> > > > ---------------------------------------------------
> > > > 
> > > > Can somebody explain me this behavior?
> > > > 
> > > > Regards,
> > > >     Stefan.
> > > > 
> > > Stefan:
> > > 
> > > When I run this test, I get the same answer with both, and it is the 
> > > same as the answer basemap.pyproj gave you.  I suspect you didn't 
> > > install the extra datum files with your command-line proj distribution.
> > > 
> > > -Jeff
> > > 
> > > 
> > > 
> > > ------------------------------------------------------------------------------
> > > Write once. Port to many.
> > > Get the SDK and tools to simplify cross-platform app development. Create 
> > > new or port existing apps to sell to consumers worldwide. Explore the 
> > > Intel AppUpSM program developer opportunity. appdeveloper.intel.com/join
> > > http://p.sf.net/sfu/intel-appdev
> > > 
> > > 
> > > _______________________________________________
> > > Matplotlib-users mailing list
> > > Mat...@li...
> > > https://lists.sourceforge.net/lists/listinfo/matplotlib-users
>