I'd like to add the tile layer behind map.atownsend.org.uk to JOSM. I believe that the resulting string should be:


Unfortunately, JOSM never sends requests for high zoom levels to the tile server. The problem isn't at the tile server end, as a request such as this gets back tiles such as https://map.atownsend.org.uk/hot/24/8342241/5383209.png. What I get back instead is a black screen for tiles from zoom levels 21/22 and up. Oddly it sometimes requests zoom 22 tiles but mostly not. it doesn't matter if the required tile is already rendered or not.

asked 21 Sep '19, 12:11

SomeoneElse's gravatar image

SomeoneElse ♦
accept rate: 16%

edited 29 Sep '19, 18:29

1 extra bit of info: I'm using JOSM 14945 (which is quite old). However, another user is also testing (presumably after seeing this help question) with JOSM 15322 and seeing the same effect (or at least, they're not sending me requests for zooms > 22 from JOSM).

(22 Sep '19, 16:04) SomeoneElse ♦

If you go into imagery preferences and look at the settings tab there is a Panel for TMS settings where you can set max and min zoom.

permanent link

answered 21 Sep '19, 15:07

InsertUser's gravatar image

accept rate: 20%

There are (at a rough guess) 1000 preferences in there and about 30 of those match the search word "zoom". Which one(s) should be changed? I did try changing one (imagery.tms.max_zoom_lvl) before asking the question but it didn't seem to have any effect.

Edit: It appears that the button that I was pressing to get to that list is actually "advanced preferences", despite it being next to a label that says "imagery preferences". JOSM is (how can I put this tactfully) "somewhat unclear" at indicating what user actions will have what effect.

(21 Sep '19, 15:24) SomeoneElse ♦

It'll probably end up there, but this is in the main imagery preferences area one tab right of the list of sources.

(21 Sep '19, 16:32) InsertUser

No, that doesn't fix it. I went into "JOSM / Imagery / Imagery preferences / settings" and in "TMS Settings" changed "Max zoom level" from 20 to 24.

On the server I can see tile requests for zoom 22:

Sep 22 15:26:31 map renderd[1810]: DEBUG: START TILE ajt 22 2084208-2084215 1344664-1344671, new metatile

but not for zoom level 23, and just a black screen in JOSM.

(22 Sep '19, 14:29) SomeoneElse ♦

JOSM seems to be acting rather oddly at these zooms.

For your example URL it seems I can get the scale in the top left to go down as far as 1.0m. OS OpenData StreetView and NLS - Bartholomew Half inch, 1897-1907 seems to (over)zoom down to between 0.5m and 0.01m depending on exactly where I look on the map. JOSM also doesn't like switching layers or panning when the zoom slider is 'against the stop'.

The Kartverket Address Overlay (WMS) seems to work OK at zoom 24 when looking at a random part of Oslo.

I think you may have found a bug.

(22 Sep '19, 16:27) InsertUser

I've logged this at https://josm.openstreetmap.de/ticket/18184#ticket

Actually, one tile request for "23/0/0.png" and "24/0/0.png" is sent, and after the latter it crashes (details on the ticket, along with the conversion function that's failing with a "Not a Number" error.

(29 Sep '19, 18:42) SomeoneElse ♦
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question asked: 21 Sep '19, 12:11

question was seen: 1,644 times

last updated: 29 Sep '19, 18:48

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