Partially missing terrain at zoom 9

[zerebubuth]

Sometimes it seems like tiles can be "partially missing" terrain. I've only seen this happen at zoom 9. The colourised terrain for parks or forests seems to show, but not the "background" grey terrain. For example, around Marin, near San Francisco, USA:

Or around Copenhagen, Denmark:

I've looked at the terrain tiles (normal PNGs) which are being loaded, and nothing seemed immediately off about them. However, the effect does reappear across Ctrl-Shift-R and in an Incognito window, which suggests it might be something to do with the data, or how it's styled.

[bcamper]

Hmm, I haven't seen this yet myself. Can you check the console any warnings/errors when this occurs? I'm wondering if it could be a problem with GL texture binding or the texture getting prematurely freed (just speculation).

We know the normal texture loaded OK, because one of the other texture tints is rendering properly.

[bcamper]

Can you also let me know what browser(s) you've seen it in?

[nvkelso]

• Safari Version 8.0.8 (10600.8.9)
• Chrome 58.0.3029.110

No console errors in either browser for me.

[nvkelso]

I've also only seen this happening at zoom 9. Zoom out to zoom 8 and the same place will render correctly, zoom in to 10 and it'll also render correctly.

[nvkelso]

Looks like the MVT format is missing land layer entirely (while other formats include land layer content). So likely an MVT encoding geometry validity problem.

[bcamper]

Drawing earth layer as red (no rasters/terrain):

Hat tip to @meetar for tracing this to the data source change.