There are two main reasons as to why you would want to proxy the WMTS basemap, these areiShare v6 and later uses MapProxy to create and display cached map data, for example aerial or historic maps. MapProxy may also be useful in other circumstances, for example:
You may have to provide a customer API Key in the URL for each request, as in the case with the OS Maps API or Get Mapping Aerial Photography. If this were to be used directly in iShare, the key would have to be transferred to the client which could expose it to misuse.
Proxying the basemap through MapProxy allows us to also query it directly with WMS which then means that it should work seamlessly with printing.
Configuration
MapProxy uses a YAML configuration file to define the layers that are available in the service and also things like the caching used and the source for the cache.
There are four parts to the configuration:
Layers
| Code Block |
|---|
- name: os_raster_road
title: os_raster_road
sources: [ "chc_os_raster_road" ] |
Caches
| Code Block |
|---|
chc_os_raster_road:
grids: [ "grd_os_raster_road" ]
sources: [ "src_os_raster_road"]
meta_buffer: 0
minimize_meta_requests: true |
Sources
| Code Block |
|---|
src_os_raster_road:
type: tile
grid: grd_os_raster_road
url: https://api.os.uk/maps/raster/v1/wmts?key=this_is_my_os_api_key&height=256&width=256&style=default&layer=Road_27700&version=1.0.0&service=WMTS&Request=GetTile&format=image/png&TileMatrixSet=EPSG:27700&TileMatrix=EPSG:27700:%(z)s&TileRow=%(y)s&TileCol=%(x)s |
Grids
| Code Block |
|---|
grd_os_raster_road:
origin: nw
srs: 'EPSG:27700'
bbox: [-238375.0,0.0,900000.0,1376256.0]
bbox_srs: 'EPSG:27700'
res: [896.0, 448.0, 224.0, 112.0, 56.0, 28.0, 14.0, 7.0, 3.5, 1.75] |
Testing
Once these are incorporated into the main configuration file, you can then test it using the MapProxy demo site which should list the layer both in the WMS and WMTS sections. Clicking on the WMTS png link will bring up an OpenLayers map which uses the specified basemap.
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Configuring the WMTS Basemap in iShare Studio
Configuring your WMTS basemap for use in iShare is done via iShare Studio and is covered in the following pages:
Increasing the number of Scales for the Basemap
Adding additional scales to a base map
The default scales may not cover the range of scales you wish to provide for your basemapbase map, and MapProxy can help with this. The cache upscale_tiles as described in the cache documentation can scale tiles up depending on your requirements.
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