[Talk-ca] GeoTiff in JOSM

Tyler Gunn tyler at egunn.com
Wed Sep 7 14:44:47 BST 2011

> I believe you can also have JOSM get files directly from your hard drive,
> but I'm not sure the syntax  to do so on the Mac.

I did a render with gdal2tiles and was able to get it working fine in
Merkaator.  Something about the tile number origin being opposite in

> Maptiler is essentially a graphical front-end to gdal2tiles. Xjjk's version
> is the command line version modified. My iMac broke awhile back so I'm not
> sure how easy/hard GDAL is to set up with python bindings on OS X.

Ah, okay.  I'll have to drop Xjik a line and see if I can get a copy
of the modified command line file.   It seems there WAS a version of
gdal2tiles tat was optimized for multi-core, but the author seems to
be charging for it.

There is a pre-made gdal install package for OSX, so it was extremely
easy to get up.  Click and install.

> You'll still be limited by your CPU :P

On a single core my 1.9GB image took around 6 hours.  So not too bad
but faster would be nice.

> What I did for testing was work on a small section downloaded separately and
> benchmarked with different image scaling methods. The three worth
> considering are nearest, antialias, and lanczos. Nearest is fastest,
> preserves sharp edges but has the worst quality. Antialias is decently fast,
> decent quality. Lanczos is the best quality, preserves edges but is
> extremely slow.

I'll have to try modifying the render settings and see how it goes.
I'll probably want to get the parallelized version first though.


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