On Thu, Jul 22, 2010 at 6:14 PM, Martijn van Exel <[email protected]> wrote:
> > On 22 jul 2010, at 06:57, Brett Henderson wrote: > > On Wed, Jul 21, 2010 at 11:52 PM, Lars Francke <[email protected]>wrote: > [...] > > That format is fine and exactly what I would have expected. I suspect > Osmosis would parse it okay, but without support for the visible attribute > it won't be particularly useful. > > > Not for visualization purposes maybe, but for analysis purposes the visible > attribute is not really an issue. My goal is to extract full history dumps > for certain spatial extents and import them into a PostGIS, in order to > calculate historical metrics exposing the crowd dynamics of OSM - for > example number of contributors over time, version growth over time, movement > of nodes over time. All this calculated for grid cells. > > The full history dump is 13GB bz2 compressed. Anyone got a rough idea how > long it would take for osmosis to extract, say, a bbox of the Netherlands > out of that on a 4GB AMD Opteron quad core machine? More RAM would probaby > help? > Osmosis is unlikely to work well on a full history dump. The --bounding-box task is really only designed to work with data from a single point in time. Data across a time range is much more difficult to accurately perform bounding box filtering, although it might be good enough. A bigger issue is that it will ignore visible attributes and strip those attributes from the output. A relatively small amount of RAM is used for a single --bounding-box task if you specify the idTrackerType=BitSet option. Brett
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