[MapProxy] Tile Source used as an overlay obscures underlying sources

[Adam Ratcliffe]

I'm seeing an issue with MapProxy 1.5.0 and trunk (1.6.0a-20130215) whereby a tile source used as an overlay obscures wms sources below it in a layer with multiple sources.

Interestingly the first time the image is requested it renders correctly, however when it is re-requested only the wms sources above the tile source appear in the image.  It appears that this is somehow related to retrieving the tiles from the cache rather than over the network as if I specify the 'disable_storage' option on the cache the image is rendered correctly every time.

A sample request from a Leaflet client looks like this: http://mapproxy.geosmart.co.nz/service?SERVICE=WMS&REQUEST=GetMap&VERSION=1.1.1&LAYERS=geosmart:traffic_incidents_nz&format=image/png&TRANSPARENT=true&HEIGHT=256&WIDTH=256&CQL_FILTER=status='current'%20AND%20(priority='0'%20OR%20priority='1'%20OR%20priority='2'%20OR%20priority='3'%20OR%20priority='7')

The relevant sections of my config are:

layers:
  - name: geosmart:traffic_incidents_nz
    title: GeoSmart Traffic
    sources: [geosmart_traffic_flow, geosmart_street_labels_cache, geosmart_traffic_incidents]

caches:
  geosmart_street_labels_cache:
    sources: [geosmart_street_labels]
    grids: [osm_grid]

sources:
  geosmart_traffic_incidents:
    type: wms
    wms_opts:
      version: 1.1.1
    supported_srs: ['EPSG:3857', 'EPSG:4326']
    req:
      url: http://geoserver.geosmart.co.nz/geoserver2.1/wms
      layers: geosmart:traffic_incidents_nz
      transparent: true
    forward_req_params: ['cql_filter']

  geosmart_traffic_flow:
    type: wms
    wms_opts:
      version: 1.1.1
    supported_srs: ['EPSG:3857', 'EPSG:4326']
    req:
      url: http://geoserver.geosmart.co.nz/geoserver_flow/wms
      layers: gps_flow_data
      transparent: true

  geosmart_street_labels:
    type: tile
    url: http://mt0.geosmart.co.nz/new/world/hires/labels/%(z)s/%(x)s/%(y)s.png
    transparent: true
    grid: osm_grid

grids:
  osm_grid:
    base: GLOBAL_MERCATOR
    origin: nw

Cheers

Adam Ratcliffe
Software Developer
GeoSmart
PO Box 101001
29 Apollo Drive, Mairangi Bay, Auckland, NZ
Ph: +64 9 966 8757
Fx: +64 9 966 8721
Email:  adam.ratcliffe at geosmart.co.nz<mailto:Phil.Allen at geosmart.co.nz>
Web:   www.GeoSmart.co.nz<http://www.geosmart.co.nz/>




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