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HumanitarianStuff / tilehuria

Minimal utility set for creating and managing MBTiles from tileservers
Apache License 2.0
7 stars 2 forks source link

maxz22 #2

Open lusdavo opened 5 years ago

lusdavo commented 5 years ago

For the mapping we are doing, we need to select some of the smallest buildings along a street or add a point next to a building, and would need to have -maxz 22 for the output .mbtiles. Currently this can be specified on the web app but seems the real processing doesn't go up to that zoom level.

ivangayton commented 5 years ago

Hi David,

TileHuria can only download tiles that actually exist on the tileserver!

Digital Globe, Bing, and Google typically serve tiles only up to level 18 or 19 (usually more in major urban areas and less in rural areas, especially in poor countries). So if you use -maxz 22, Tilehuria will try to download up to level 22, but these tiles will usually not exist.

Tilehuria doesn't use "processing" to generate tile levels, it just downloads what's available on the TMS (it does process tiles by compressing them to JPEG, which in the case of Digital Globe in particular results in a huge―around 3X―reduction in file size, but that's the only "processing" it does).

To check the resolution available in a given area, zoom to it in JOSM using the relevant imagery, and see what level of detail you can see. If there aren't high-resolution tiles on Bing, Digital Globe, and Google, TileHuria cannot create them.

If you find an area where you can see higher-resolution tiles in JOSM than you can it the TileHuria MBTiles set, please send me a copy of the AOI and I'll investigate; that would presumably be a bug in TileHuria.

lusdavo commented 5 years ago

@ivangayton great, and good to know that. Please see here AOI - ganta_phase01.zip

lusdavo commented 5 years ago

Also, here is the generated .mbtiles for that AOI

ivangayton commented 5 years ago

Hi @lusdavo, as far as I can see, the tiles here match exactly the tiles in DG Premium in the QuickMapServices plugin (the tiles in this area only go up to level 18).

I think―in this case anyway―TileHuria is fetching as much detail as actually exists in the DG Premium tileset.

lusdavo commented 5 years ago

Ok - would be great to have TileHuria spit .mbtiles up to that level. Not sure yet how that can be done, but maybe something to consider with upcoming improvements.

ivangayton commented 5 years ago

@lusdavo It can be done if: a) TileHuria deploys a fleet of satellites, or b) TileHuria deploys a fleet of drones! ;-)

Otherwise it's quite difficult to get high-resolution imagery when the commercial providers don't have it on their servers!