[MapProxy] Stretching local tiles for TMS requests with higher zoom levels than stored

[Mario Köpping]

Hi everyone,

I have mapproxy providing a TMS service for tiles that I store locally (on my notebook, later on a server). These tiles are pre-generated in a certain range of zoom levels, let's say 0-12. Since the source has a resolution of 100m*100m per pixel and I'd like to limit computation time and storage space, I don't want to pre-generate higher zoom levels. However, it should be possible to zoom in further. Therefore, I'm looking for a way to configurate mapproxy so that it delivers stretched images based on the pre-generated tiles whenever a higher zoom level is requested. If possible, I'd prefer to realize this in mapproxy, since the Leaflet client I'm using does not seem to support something like this natively and I can't change the client.

>From the documentation, I found that the definition of a custom grid and the stretch_factor option could help. However, I tried many things and I just can't get it to work. I'd really appreciate it if someone could help me with this. You can find a minimal configuration below.

Thank you in advance,

Mario


Minimal configuration:

services:
  tms:  

sources:
  corine_tile_source:
    type: tile
    url: file:///C:/Projects/mapserver/data/corine/%(z)s/%(x)s/%(y)s.png
    
grids:
  mygrid:
    base: GLOBAL_MERCATOR
    num_levels: 13
    stretch_factor: 10.0
    
caches:
  corine_tile_source_cache:
    sources: [corine_tile_source]    
    grids: [mygrid]
    cache:
      type: file
      directory_layout: tms
      directory: C:/Projects/mapserver/data/cache/corine
      
layers:
  - name: corine_tiles
    title: Local Corine Tiles
    sources: [corine_tile_source_cache]

 		 	   		  
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