Raster prerendering seams

[lbud]

rasterize seamquest is apparently not over:

[mourner]

This time it looks different...

[lbud]

@mourner this actually does look like something @ansis and I were seeing during the original seamquest, just thought we fixed it pretty quickly because some of the seams (?) (at least all of the seams we were looking at) disappeared, and they're still not around in the locations where they were before...

[mourner]

@lbud I don't know, on previous screenshots the seams were barely visible, while on this one there's a clear gap between tiles.

[lbud]

well...did some snooping around and checked out the commit that merged that branch (a632597) and sure enough, we have seams 😕 .

They weren't showing up in all the places I was looking before and are weirdly hard to find, but they are certainly there -- I'll investigate some more

[lbud]

erm, happens on non-prerendered tiles as well (this is outdoors-v4)

[mourner]

Hmm... How does outdoors look in native?

[lbud]

hMMmmm. Good thought -- also broken.

[mourner]

Then it looks like a terrain data problem, @ajashton thoughts?

[ajashton]

There is an 8px buffer of redundant data around each 256px tile to allow for blurring, etc Mapnik. There are some hard edges every 4th tile that are side effects of the processing, but I don't see how gaps like this screenshot would be caused by the data.

[lbud]

Closing this as a data issue (ticketed in terrain)