I’m seeking other users experience with Background Maps in FME Workbench/Form.
I use OpenStreetMap.org tiles (and sometimes MapBox tiles) as background maps when following data through a workspace. But more often than not maps take more than 30 seconds to appear, or not all.
I originally assumed it was my organisations VPN, or security software agents, or network bottlenecks, but my independent tests on other external systems ruled these out.
So I explored other possibilities.
Here is a view of network traffic on my machine with a map at the town level. Not much happening.
But look what happens when I then Zoom to Extents so the maps scales to all of Australia. Look at the spike in network traffic - some 6MB to draw a map?
From what I can estimate FME is requesting hundreds and possibly thousands of map tiles for any given zoom request.
What happens next is that OSM will either block or possibly throttle my IP for a period of time.
Mapbox seems to perform better, but looking at my stats I’m churning through quota. Possibly when I hit the included quota I’ll get throttled or billed, neither of which is that appealing.
My understanding of XYZ tiles is that you need the same number of tiles at ANY zoom level. The number of tiles should be around 20-30 per map window depending on the shape (square or elongated rectangle). That’s the visible tiles, plus the edge tiles, plus maybe one more row and column of tiles off screen ready for panning.
But FME is requesting about 6MB which works out to be 500 to 1000 tiles for Australia-level zoom.
To confirm it was a throttling issue, I set up an OSM Map Tile Server on a locally-hosted server. The maps appear every time, although sluggish with the volume of data being requested. But I at least get a map and not a grey background.
Other things I considered:
- is FME re-projecting OSM map tiles on the fly?
- does FME use whole zoom levels (15,16,17) or does it scale/resize the tile to the window (15.1,15.2,15.3)?
- is FME using cached tiles or requesting from OSM/Mapbox every time?
I’m keen to know if I’m the only one frustrated with debugging data in the Visual Preview.
OSM Tile Usage Policy: https://operations.osmfoundation.org/policies/tiles/
