[OSM-talk] Databases?

Jochen Topf jochen at remote.org
Wed Oct 15 17:07:36 BST 2008


On Thu, Oct 16, 2008 at 03:49:11AM +1200, Joseph Gentle wrote:
> On Thu, Oct 16, 2008 at 3:18 AM, Andy Allan <gravitystorm at gmail.com> wrote:
> > 'Better' is dependent on what you're trying to achieve, but there are
> > certainly many 'different' representations in use in different
> > projects.
> 
> I want to represent the data such that a user can pan and zoom a map
> around smoothly (25+ fps) without pre-rendering tile images.
> Especially on devices like the iphone, that would be really nice.
> 
> The only data structure I can think of to do something like this would
> be a quad tree with internal nodes containing data at particular
> detail levels. (So that for a fixed size view you never have to
> inspect more than a fixed number of quad tree nodes).
> 
> Basically, it would look the same as the current tile set; but
> prerendered tile images would be replaced with node&way lists listing
> the data the corresponding tile shows.
> 
> Has anyone written a program like this; either with that sort of data
> format or solving that problem?

Have a look at "navit". Although 25+ fps is somewhat optimistic for a
mobile device... (http://wiki.openstreetmap.org/index.php/Navit)

I use postgis for live rendering of OSM data and generally it is very fast.
But OSM has huge amounts of data and you'll have to make compromises
somewhere.

Jochen
-- 
Jochen Topf  jochen at remote.org  http://www.remote.org/jochen/  +49-721-388298





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