On 03/18/2011 02:55 PM, Ralf Kleineisel wrote:
On 18.03.2011 14:45, WanMil wrote:
Yes, we provide the same option for coastlines. So it's possible although there is the size restriction. Boundaries take around 3% of the complete OSM data (3% as osm.gz compared to osm.pbf). So think about creating a europe map from the 4.5 GB dump. The boundary data file would be around 3%*4.5GB(osm.pbf) = 135MB(osm.gz). So in the end your computer additionally needs as much main memory as you need to compile a 135MB big tile.
Wouldn't it be enough to keep that part of the boundaries in memory which lie in the area of the map tile mkgmap is processing?
Yes. For this we need: * A preprocessing that converts the (complete) boundary file to a file format that allows to load parts only. This may be one file for each 1°x1° part. * mkgmap would have to load the relevant parts during tile processing. Each boundary area gets and unambigious id so we could merge them easily when a tile overlaps more than one 1°x1° boundary part. * The boundary information might be ignored while loading the tiles. The same algorithm can be reused for coastline processing. WanMil