[MapProxy] Quality Issue with PNGs from cache

Poul Kjeldager Sørensen pks at ascend.xyz
Sun Nov 2 23:05:24 PST 2014

My first mail to this mailing this and a little new to this, so hoping it get to the right people.


In the image in the link I have shown the issue by comparing the images served by WMS and the original png files in the cache folder on disk. (using a GIS application to show boths).

I have the following configuration, where I seeded tiles cache folders. I made two examples, one where the tile_size is larger than the other:

  - name: tiles_to_wms
    title: Tiles to WMS test
    sources: [test_cache]
   sources: []
   grids: [my_grid]
   meta_buffer: 0
   meta_size: [1,1]
   format: image/png
   cache_dir: "C:/ascend-vd/Sjaeland/11 - kbh-holbaek-lumaas"
   sources: []
   grids: [test_grid]
   format: image/png
   cache_dir: "C:/ascend-vd/Sjaeland/11 - kbh-holbaek-lumaas"
    tile_size: [8192, 8192]
    bbox: [-1878007.03, 3932282.86, 832014.23, 9436480.79]
    res: [61.3423104 ,30.6711552,15.3355776,7.6677888,3.8338944,1.9169472,0.9584736,0.4792368,0.2396184,0.1198092,0.0599046]
    srs: 'EPSG:25832'
    origin: sw

    tile_size: [2048, 2048]
    bbox: [-1878007.03, 3932282.86, 832014.23, 9436480.79]
    res: [61.3423104 ,30.6711552,15.3355776,7.6677888,3.8338944,1.9169472,0.9584736,0.4792368,0.2396184,0.1198092,0.0599046]
    srs: 'EPSG:25832'
    origin: sw

I also modified the script to print out when it reads a file from disk and testing in the console:

Tile((20642, 18515, 10), source=None)
C:/ascend-vd/Sjaeland/11 - kbh-holbaek-lumaas\test_cache_EPSG25832\10\000\020\642\000\018\515.png
Tile((20643, 18515, 10), source=None)
C:/ascend-vd/Sjaeland/11 - kbh-holbaek-lumaas\test_cache_EPSG25832\10\000\020\643\000\018\515.png
Tile((20642, 18514, 10), source=None)
C:/ascend-vd/Sjaeland/11 - kbh-holbaek-lumaas\test_cache_EPSG25832\10\000\020\642\000\018\514.png
Tile((20643, 18514, 10), source=None)
C:/ascend-vd/Sjaeland/11 - kbh-holbaek-lumaas\test_cache_EPSG25832\10\000\020\643\000\018\514.png
[info] - - [03/Nov/2014 07:51:50] "GET /service?VERSION=1.1.1&SERVICE=WMS&REQUEST=GetMap&LAYERS=tiles_to_wms&FORMAT=image/png&STYLES=&SRS=EPSG:25
832&BBOX=654451.973,6203718.15,654620.003,6203814.286&WIDTH=2433&HEIGHT=1392&TRANSPARENT=TRUE HTTP/1.1" 200 -

If I used my other cache with larger tiles the quality is equal as the original data, but as seen below it also only loads one image and I am guessing its not doing anything other than cropping it:

d-vd/Sjaeland/11 - kbh-holbaek-lumaas\my_cache_EPSG25832\10\000\005\160\000\004\628.png - - [03/Nov/2014 08:02:56] "GET /service?VERSION=1.1.1&SERVICE=WMS&REQUEST=GetMap&LAYERS=tiles_to_wms&FORMAT=image/png&STYLES=&SRS=EPSG:25
=654450.487,6203719.192,654618.5,6203815.357&WIDTH=2432&HEIGHT=1392&TRANSPARENT=TRUE HTTP/1.1" 200 -

Is there anyway that I can get my test_cache to work, without it lowering the quality of the served pngs.

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