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<p class="MsoNormal">I discovered that using MapProxy with pyproj you cannot successfully reproject to an SRS that uses units different from meter.<o:p></o:p></p>
<p class="MsoNormal">In my case I tried to reproject OSM data into EPSG:32019 which resulted in wrong tiles.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The issue is caused by a nasty behavior of the pyproj library which has already been mentioned in multiple pyproj issues, see here:
<a href="https://github.com/jswhit/pyproj/issues/67">https://github.com/jswhit/pyproj/issues/67</a><o:p></o:p></p>
<p class="MsoNormal">Software using pyproj should use the additional parameter “preserve_units=True” when instantiating a new class, e.g.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">ny_state = pyproj.Proj(init="EPSG:2263", preserve_units=True)<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Currently MapProxy does not set this parameter, by that pyproj assumes that each SRS is based on “units=m”.<o:p></o:p></p>
<p class="MsoNormal">I’ve successfully tried a quick fix in mapproxy’s proj.py (I’m not a Python developer at all, so there might be nicer solutions):<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">def try_pyproj_import():<o:p></o:p></p>
<p class="MsoNormal"> try:<o:p></o:p></p>
<p class="MsoNormal"> from pyproj import Proj, transform, set_datapath<o:p></o:p></p>
<p class="MsoNormal"> except ImportError:<o:p></o:p></p>
<p class="MsoNormal"> return False<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal"> # this new class overrides the constructor of the Proj class to set preserve_units to True by default<o:p></o:p></p>
<p class="MsoNormal"> class myProj(Proj):<o:p></o:p></p>
<p class="MsoNormal"> def __new__(self, projparams=None, preserve_units=True, **kwargs):<o:p></o:p></p>
<p class="MsoNormal"> return super(myProj, self).__new__(self,projparams,preserve_units,**kwargs)<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal"> log_system.info('using pyproj for coordinate transformation')<o:p></o:p></p>
<p class="MsoNormal"> return myProj, transform, set_datapath<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Best regards<o:p></o:p></p>
<p class="MsoNormal">Martin<o:p></o:p></p>
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