[OSM-talk] Ideas for student project on OSM

[Freek]

On Tuesday 28 October 2008, Nic Roets wrote:
> Well, I'm really pleased with the performance of the fixed tile size
> algorithms I implemented in gosmore. OSM data is remarkably "flat" : Either
> a tile is empty (sea / rural / unmapped) or has approximately the same
> number of objects as any other urban tile. So if the tiles are small enough 
> you don't need a second index (e.g. subdividing the tiles).

Interesting observation... 

> * Arrange the tiles in a 2-D Hilbert curve to reduce disk seeks

Still, I think the idea of Asano et al. [1] applies because you are retrieving 
a set of square tiles within a rectangular query region (with a reasonable 
aspect ratio), but I don't know if it's really noticeably better in practice.

[1] Publicly available version: 
ftp://ftp.inf.ethz.ch/doc/papers/ti/grpw/SFC.ps.gz

-- 
Freek