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Key to look up in m2i for zoom/extent: watercolor_h8vqbF00cW0

Traceback (most recent call last):
  File "queue_popper_multi.py", line 71, in main
    ms.process_map(db_item,msg)
    map = self.create_map(db_item,provider,mime_type,dim)
    roughZoom = ModestMaps.mapByExtent(provider, se, nw, dim)
Processing... watercolor_h8vqbF00cW0
  File "/app/mapsettings.py", line 232, in create_map
  File "/app/ModestMaps/__init__.py", line 119, in mapByExtent
    mapCoord, mapOffset = calculateMapExtent(provider, dimensions.x, dimensions.y, locationA, locationB)
  File "/app/mapsettings.py", line 273, in process_map
  File "/app/ModestMaps/__init__.py", line 179, in calculateMapExtent
    hZoomDiff = math.log(hFactor) / math.log(2)
None
ValueError: math domain error

In Geo.py Transformation.untransform, on the input, it is expected (at least how ModestMaps is used by TileStache), that the input point coordinates are representing row and column of requested tile.

According to http://blog.kartena.se/local-projections-in-a-world-of-spherical-mercator/, cx and cy parameters are supposed to be Origin of the tile set, which is given in map units (meters in my case).

Therefore, the transform/untransform function can not work well, if cx and cy parameters are given in map units, because it's calculating with input rows/columns.

Either the code is wrong, or it's usage in TileStache or my understanding of Transformation (based on the blog mentioned earlier)

class Transformation:
...
    # point uses coordinates representing columns/rows of given tile
    # cx and cy are given in map units (meters) of the tile set origin - or maybe not?
    def untransform(self, point):
        return Point((point.x*self.by - point.y*self.bx - self.cx*self.by + self.cy*self.bx) / (self.ax*self.by - self.ay*self.bx),
                 (point.x*self.ay - point.y*self.ax - self.cx*self.ay + self.cy*self.ax) / (self.bx*self.ay - self.by*self.ax))

Is there any interest in porting to Python3?

I have some scripts I'd like to use in Python 3, and I'd like to port ModestMaps to Python3. But I'd like to merge upstream, I don't see a reason to create two separate forks.

Thanks!

See stamen/fieldpapers#299 (comment)

If a request fails, MM will retry to the request at a lower zoom. However, if the lower zoom fails, it will continue to do so well into negative values for zooms.

Full license text statement is missing in this project. BSD license is mentioned
only in the setup.py file. This is challenging because there are many different
specific licenses in the BSD family.

Could you please commit a particular BSD license text?