3 ms·

Hmm, I'm curious about how much this is overstating the effectiveness of the optimizations in order to teach about them. With this approach, (it seems like) you

Hmm, I'm curious about how much this is overstating the effectiveness of the optimizations in order to teach about them. With this approach, (it seems like) you would still have to render the highest zoom level first, which already takes 3/4 the render time anyway. There are lots of other optimizations you can do (and they probably are doing) there, but they aren't related to the tree/reference-based ones mentioned here. The presentation also seems to overstate the redundancy found in the land tiles. You would get savings from water tiles at all zoom levels, which would be enormous, but (looking at http://mapbox.com/maps http://mapbox.com/maps) even if humans only cover 1% of the land, our infrastructure is well enough distributed that it and inland water and other details they've included would preclude redundancy at all but the highest zoom levels (although, in this case, the highest zoom level taking up 3/4 of the tiles saves the most). With that in mind, I'm wondering about the claimed rendering time of 4 days. That fits nicely with the story told, but with the 32 render servers mentioned at the end, that would seem to be 128 CPU days (though I'm not sure about the previous infrastructure they were comparing it to), which is actually close to the count mentioned early on with a super-optimized query and render process. This is all just supposition, so I don't want to sound too sure of myself, but the storage savings seems to be the big win here (60% from water + redundancy at highest zoom levels), while I would guess that you would save considerably less in processing (15% from water + minor redundancy on land (absent other optimizations e.g. run-length-based ones)).

Retric 15y ago
Try zooming in on Russia, Alaska, Brazil, or Egypt and you find a lot of empty tiles. Still, if you can render the whole thing in 4 days I suspect caching what people actually look for would be good enough as people probably hit max zoom on manhattan 1000x as much as they do on some random village in the amazon. The advantage being you can just invalidate tiles as you get new information vs trying to render the whole thing every time you get new street data for Ohio.
- magicalist 15y ago
  True, and countries that are empty except for random river squiggles can save a good bit of storage (at the highest zooms so those river squiggles are isolated), but, again, if you have to start with the lowest level first, the described approach isn't saving a whole lot in processing time, even with big empty space. One thing I forgot to say in my top post, though, is the presentation mentions compositing layers together on the fly, and that is one of the key tools they use, but the presentation drops that thread. I'm curious if originally it had more on that front and what they do with that.
- mncaudill 15y ago
  And there's actually a project that takes advantage of that fact: https://github.com/nvkelso/golden-ratio https://github.com/nvkelso/golden-ratio
leddt 15y ago
Regarding starting from the highest zoom level, I believe it's the other way around. If, for example, at z2 a tile is all water, then it is also all water at all higher zoom levels, which can then be skipped.

Retric 15y ago

Try zooming in on Russia, Alaska, Brazil, or Egypt and you find a lot of empty tiles. Still, if you can render the whole thing in 4 days I suspect caching what people actually look for would be good enough as people probably hit max zoom on manhattan 1000x as much as they do on some random village in the amazon. The advantage being you can just invalidate tiles as you get new information vs trying to render the whole thing every time you get new street data for Ohio.

magicalist 15y ago
True, and countries that are empty except for random river squiggles can save a good bit of storage (at the highest zooms so those river squiggles are isolated), but, again, if you have to start with the lowest level first, the described approach isn't saving a whole lot in processing time, even with big empty space. One thing I forgot to say in my top post, though, is the presentation mentions compositing layers together on the fly, and that is one of the key tools they use, but the presentation drops that thread. I'm curious if originally it had more on that front and what they do with that.
mncaudill 15y ago
And there's actually a project that takes advantage of that fact: https://github.com/nvkelso/golden-ratio https://github.com/nvkelso/golden-ratio

leddt 15y ago

Regarding starting from the highest zoom level, I believe it's the other way around. If, for example, at z2 a tile is all water, then it is also all water at all higher zoom levels, which can then be skipped.