[OSM-dev] bad pngs from mod_tile / renderd & meta files

Iván Sánchez Ortega ivan at sanchezortega.es
Fri May 1 19:16:28 BST 2009

El Viernes, 1 de Mayo de 2009, jburns escribió:
> I am having a problem in that the pngs being generated and returned by my
> apache & renderd & mapnik process are not "proper" pngs in that they are
> rejected by various file viewers as being malformed.
> Any ideas or tips where to start debugging this one?

First thing I'd do is to really check that the pngs are malformed. Please try 

$ wget localhost/tiles/0/0/0.png
$ hexdump -c 0.png | head

You should see something like this:

0000000 211   P   N   G  \r  \n 032  \n  \0  \0  \0  \r   I   H   D   R
0000010  \0  \0 001  \0  \0  \0 001  \0  \b 003  \0  \0  \0   k 254   X

What exactly do you see when you do an hexdump of one of our PNGs?? Sometimes, 
when there is an error while generating the image, you may see an error 
message intertwined in there.

Iván Sánchez Ortega <ivan at sanchezortega.es>

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