OpenStreetMap 開放街圖
Took my first osm xml file download yesterday – rhone-alpes.osm from CloudMade, 52m lines in 3.95Gb (uncompressed) so hardly planet.osm. Even so the parsing program needs large file support “cc -D_FILE_OFFSET_BITS=64”
First steps taken to parse out the node lat&lon pairs into array of doubles. Highest node id in rhone-alpes is 1.543.458.302 = 1.54Gnodes. Assuming this is not outrageously different from the number of nodes in planet.osm, we could store the lat&lon pairs for the planet in ~25Gb (2x8 bytes x 1.5Gnodes). That’s definitely do-able.
17m nodes of rhone-alpes loaded in 62 seconds on bog-standard laptop, so ~1.5hrs for the planet?
討論
由 giggls 於 2012年03月26日 10時19分 發表的評論
For new software pbf format will always certainly be the better choice than osm format.
由 Jochen Topf 於 2012年03月31日 12時18分 發表的評論
You can store the coordinates as integers and you’ll only need half the space. See the storage/byid stuff in Osmium on how this can be done. The reason this works is that the precision of the coordinates is limited anyway, because internally the OSM server also stores the coordinates as integers.