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opensciencemap / vtm

a vector-tile map library written in java - running on android, desktop and within the browser
GNU Lesser General Public License v3.0
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vtm vs mapsforge #14

Open rakucmr opened 10 years ago

rakucmr commented 10 years ago

How different is vtm format compared to mapsforge format? Can vtm be exported in standalone files like mapsforge map files? Is smaller then mapforgeformat?

hjanetzek commented 10 years ago
  1. The mapsforge format is well suited for offline maps as it provides tile indexes and has less redundancy. It only contains data for a few base zoom-level from which intermediate zoom-levels are derived. The vtm format (in its current form) is intended for online maps and on-the-fly tile creation on the server. It uses Protocolbuffers for serialization which makes it easier to extend(and experiment with).
  2. One could put vtm tiles in a sqlite store for offline use. The vtm-android tile cache could serve as an example
  3. No. Though in the end it depends on what data you put into it -- the mapsforge file writer does a bad job on generalizing data on low zoom-levels (like merging lines belonging to one road or joining adjacent areas of the same type). For OpenGL rendering we needed better generalization.
MarsVard commented 10 years ago

are there any tutorials about how to store the vtm files in an sqlite db and actually use it?

apachemaven commented 9 years ago

I have thought do some offline job by vtm, however it seems that it is not a good choice to use the current vtm tiling manner(ont tile for certain one zoom) since there are too much redundancy.

So I think one should custom the tile source and tile format to serve more zoom levels by a certain zoom tiles. Which will make the offline map file smaller.