[OSM-talk] New mass imports over existing data

Beej Jorgensen beej at beej.us
Fri Dec 19 02:16:48 GMT 2008

Hey all,

This is sort of a general question with a specific example, namely,
Marin County.

Marin County (just north of the Golden Gate Bridge and San Francisco,
California) already exists in OSM.  It's made of bad TIGER data that has
been partially corrected (by myself and others).  Streams and trails
have been added.  Parks have been outlined.

Now it has recently come to light that Marin County provides Free data
covering the county, and this Free data is of excellent quality.  Roads,
trails, hydro, and even structure footprints are included.

Now, there are a few courses of action I can imagine.

1. Indiscriminately blow away all of Marin and replace it with County
data.  If you made changes, tough luck.

2. Discriminately blow away specific pieces of the data and replace them
with County data.  For example, maybe just Mill Valley's roads could be
replaced, because very little correction has been done there.

3. Using JOSM or somesuch, visually overlay the OSM data over the County
data and manually adjust and add ways (cut-n-paste to add) as appropriate.

I doubt there's a specific course of action that would work for all
cases like we have in Marin County, but are there any other approaches
people can think of, or pros or cons?


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