Simplification to 2.5M seems a reasonable decision to me, possibly even up to 5M if it results in a significant reduction in data volume.
Dropping the two FCodes sounds like a reasonable idea. They can always be added at a later date if desired, and imported at other levels of simplification at that time. Dale On Sun, Oct 28, 2012 at 11:58 PM, Michal Migurski <[email protected]> wrote: > 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 > -- Dale Puch
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