[Talk-us] What to do with unnamed NHD streams

Phil! Gold phil_g at pobox.com
Mon Oct 29 14:00:20 GMT 2012


* Paul Norman <penorman at mac.com> [2012-10-28 20:51 -0700]:
> 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.

I do a lot of tracing streams from aerial imagery with the NHD as an
overlay for names and pointers as to the flow locations.  (I prefer
tracing to importing because I can achieve much better accuracy than the
NHD, plus I ensure that the waterways interact properly with roads by
adding bridges and tunnels as necessary.)

Based on my experience with the NHD, I think an import should probably
include FCode 46006 streams; I've seen quite a few decent-sized streams
without names that I feel definitely enhance the map by their presence.  I
probably wouldn't have objections to removing FCode 46003 streams, but be
aware that the NHD is the product of a lot of different people entering
data over a span of many years (sound familiar?) and the threshold between
46006 and 46003 can vary significantly from area to area, presumably
depending on the judgement of the pople entering the data.

-- 
...computer contrarian of the first order... / http://aperiodic.net/phil/
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