On Oct 28, 2012, at 8:51 PM, Paul Norman wrote: > Background: I'm working on converting NHD to .osm format > > … > > 2. Some ways are very over-noded. The NHD accuracy standard is <12m error > 90% of the time. Running a 1m simplify in JOSM reduces the number of nodes > to 25%-50% of what it was before. Like everything with the NHD, this varies > from region to region. I'm thinking a 2.5m simplification would be best - > it's 1/5th of the accuracy standard. Of course, running a simplification on > a dataset this large is a challenge in itself.
Does it all come in shapefile form? The simplification would be a relatively easy (though time-consuming) task for PostGIS on a server with sufficient storage, outputting new shapefiles for ogr2osm. I can help with this using one of our office servers that we use for such tasks. > 3. A lot of NHD is very minor streams "only of use to hydrologists." There > are streams that you would be hard pressed to locate if you were there in > person and in some cases they do not exist anymore. > > A sensible solution in any NHD translation may be to drop any FCode 46003 > (intermittent) streams without a name. It may also be worth dropping FCode > 46006 (perennial) streams without a name. Can these be simplified to a lower level of accuracy? -mike. ---------------------------------------------------------------- michal migurski- [email protected] 415.558.1610 _______________________________________________ Talk-us mailing list [email protected] http://lists.openstreetmap.org/listinfo/talk-us
