[OSM-dev] Call to mobile developers: OSM binary file format

Shaun McDonald shaun at shaunmcdonald.me.uk
Thu Aug 7 10:47:55 BST 2008


Chris Browet wrote:
>
>
>     Do you think about floating-point or fixed-point
>     coordinates?
>
>
> This is one of the things to discuss. For mobile applications, 
> fixed-point is the most efficient but we have to balance this with the 
> loss of precision.
Actually the OSM db stores the node's lat and lon as integers. There is 
a scaling factor of 10000000 done on the fly when you read and write notes.
http://trac.openstreetmap.org/browser/sites/rails_port/lib/geo_record.rb#L22

Shaun





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