[OSM-dev] OSM PBF and spatial characteristics of blocks

Andrew Byrd andrew at fastmail.net
Wed Jan 6 13:57:29 UTC 2016


On 06 Jan 2016, at 13:56, Stadin, Benjamin <Benjamin.Stadin at heidelberg-mobil.com> wrote:
> The problem I have to solve is that I need to be able to export also to other projections. For our indoor navigation and accurate site maps we have to use a proper projection. Thus my idea to index WGS84 datum, and enble to index oberlappings efficiently. When this is solved it should be possible to load WGS84 data cells that overlap a world area for a given projection (using the bbox from input, loading overlapping MODIS cells) and cut the export at the bounding sites later on.

You can do a similar kind of spatial indexing on raw WGS84 coordinates. It is more compact to store WGS84 coordinates as fixed-precision ints than as doubles (single-precision floats are not precise enough worldwide), and you can insert those int coordinates into an implicit quad tree in the same way map tiles work, just by shifting low order bits off.

-Andrew


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