Hi,
I'm using a real empty tile ("empty.png") as a reference for all empty
tiles.
Here is the code snippet:
empty= ''
if bytes == 137:
empty = " Empty Tile "
if "__EMPTY" not in render_tiles.__dict__:
render_tiles.__EMPTY_FILENAME = "empty.png"
if os.path.exists( render_tiles.__EMPTY_FILENAME ):
render_tiles.__EMPTY = open(
render_tiles.__EMPTY_FILENAME, 'rb' ).read()
else:
render_tiles.__EMPTY = None
if "__EMPTY" in render_tiles.__dict__:
if render_tiles.__EMPTY != None:
if os.stat( tile_uri )[6] == len(
render_tiles.__EMPTY ):
if open( tile_uri, 'rb' ).read() ==
render_tiles.__EMPTY:
os.remove( tile_uri )
print ">" * 10, "Empty tile erased:",
tile_uri
cheers
jürgen
Hemant Bist-2 wrote:
>
> Hi,
> Sending it again since first mail somehow didn't make it
> Hb
>
> On Nov 29, 2009, at 9:22 PM, Hemant Bist <[email protected]> wrote:
>
>> Hi,
>> Mapnik is correctly generating the tiles for me.
>> I am trying to figure out if Mapnik can tell me if the tile (or map
>> I generated) is empty(i.e. there is no information in the tile).
>> I have a sparse map with few polygons covering less than 50% of the
>> total map rendered.
>>
>> The empty tiles have small size so that would be one heuristic. I
>> am hoping there is some better way: either Mapnik can tell me or may
>> there is some imagemagick or some other tool that can check that all
>> the pixels in the png are transparent(I am using transparent
>> background).
>>
>> I am currently using generate_tiles.py.
>>
>> Would appreciate any pointers. In past I have benefited from
>> suggestion for workarounds on this list, even if there is no direct
>> solution.
>>
>> Happy Holidays!
>> HB
> _______________________________________________
> Mapnik-users mailing list
> [email protected]
> https://lists.berlios.de/mailman/listinfo/mapnik-users
>
>
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