[MapProxy] Problems creating WMS from existing Tile Server

[Thomas Konrad]

Hello,

first of all: Thanks for creating MapProxy and for making it so well-documented and Open Source!

I’m currently trying to create a WMS service out of a WMTS tile service (so I need a conversion between the two formats) and I’m having trouble with it. The source is the ViennaGIS multi-porpose map (https://www.wien.gv.at/stadtplan/). The capabilities document is here: http://maps.wien.gv.at/wmts/1.0.0/WMTSCapabilities.xml. I followed the instructions at http://lists.osgeo.org/pipermail/mapproxy/2013-August/001674.html to calculate the right scale factors and generally followed http://mapproxy.org/docs/nightly/configuration_examples.html#create-wms-from-existing-tile-server for the basic configuration (by the way, I’m using the 1.7.0a nightly build).

Here’s the configuration I came up with (mapproxy.yaml):

##########################################

services:
  demo:
  wms:
    md:
      title: ViennaGIS Multi-Porpose WMS Server

layers:
  - name: vienna_gis
    title: ViennaGIS Multi-Purpose Map (WMS layer)
    sources: [vienna_cache]

caches:
  vienna_cache:
    grids: [vienna_grid] # GLOBAL_WEBMERCATOR? -> Gives "BBOX does not align to tile"
    sources: [vienna_source]

sources:
  vienna_source:
    type: tile
    grid: vienna_grid
    url: http://www.wien.gv.at/wmts/fmzk/pastell/google3857/%(z)s/%(y)s/%(x)s.jpeg

grids:
  vienna_grid:
    srs: 'EPSG:3857'
    origin: 'nw'
    bbox: [1799448.394855, 6124949.747770, 1848250.442089, 6162571.828177] # Is that the right SRS? How do I know?
    res: [
         #  res            level     scale @90.7 DPI
       156543.0339281200, #  0   559082264.02900004
        78271.5169642000, #  1   279541132.01499999
        39135.7584819600, #  2   139770566.00700000
        19567.8792410080, #  3    69885283.00360000
         9783.9396205040, #  4    34942641.50180000
         4891.9698102520, #  5    17471320.75090000
         2445.9849051260, #  6     8735660.37545000
         1222.9924525644, #  7     4367830.18773000
          611.4962262808, #  8     2183915.09386000
          305.7481131404, #  9     1091957.54693000
          152.8740565705, # 10      545978.77346600
           76.4370282852, # 11      272989.38673300
           38.2185141425, # 12      136494.69336600
           19.1092570713, # 13       68247.34668320
            9.5546285356, # 14       34123.67334160
            4.7773142678, # 15       17061.83667080
            2.3886571339, # 16        8530.91833540
            1.1943285670, # 17        4265.45916770
            0.5971642835, # 18        2132.72958385
            0.2985821417, # 19        1066.36479193
    ]
    tile_size: [256, 256] # That sould be default anyway

##########################################

When I start the server and try to open the demo page for the newly created WMS service, it tells me:

    Could not get any sources:
    HTTP Error „http://www.wien.gv.at/wmts/fmzk/pastell/google3857/11/0/1.jpeg“: 404

So we’re seemingly somehow outside of the bounding box. When I intercept the traffic of JOSM for example, I see way higher numbers for the X and Y values. So I guess the tile index calculation is wrong in some way. The ViennaGIS WMTS service is also pre-configured in JOSM for if you want to try it out there (Vienna: Mehrzweckkarte (general purpose) - tms[19]:http://www.wien.gv.at/wmts/fmzk/pastell/google3857/{zoom}/{y}/{x}.jpeg).

First I thought that the demo uses a random bounding box for the WMS service and therefore does not find the tiles, but then I saw in the JavaScript source code that it does center the map view correctly according to the bounding box I defined.

Some questions that came to my mind while configuring MapProxy:
 - How can I determine which bounding box SRS I should use? In the capabilities document above, the box is given as very high numbers, whereas in other configuration examples i saw the box defined in degrees.
 - Can I use two different grids for the service and the source? Does the conversion work in all cases? When I use GLOBAL_WEBMERCATOR as a grid for the „cache“ section, the demo says „Could not get any sources: BBOX does not align to tile.“
 - If a tile map service is limited to a bounding box, do the tiles usually start with 0/0 or with the generic index of that place?

I’m kind of stuck here. Is anyone so nice as to point me towards the right direction?

Thanks in advance
Thomas