[Imports] California farm data
srmixter at hotmail.com
Sun Oct 24 16:22:33 UTC 2010
The California State Department of Conservation Farmland Mapping
and Monitoring Program (FMMP) has given OpenStreetMap permission to use
their farm data under a public domain license. They just request
attribution. To comment about the proposal, go to http://wiki.openstreetmap.org/wiki/California_Farms.
We should import the new 2010 data when it comes out hopefully by the
end of the year. Currently just the 2008 data is available. The data
can be posted and then people who are familiar with the areas can
download them, clean them up in JOSM and then upload. They should
compare the FMMP data with the existing data and then replace the old
farm data with new farm data when possible.
We should use this data set for importing just the farmland. The
other land areas, urban lands and grazing areas could come in handy when
needing to add a zone to a city that hasn't been zoned but in general
shouldn't be used. The water layer should also be avoided because the
NHD import is better.
This data is included in the California Land Cover import, but this
data is more accurate and should be done first before that import is
Updating- The data is updated every two years. FMMP is looking for a
way to be able to update the data when it is changed and also to see
what changes have been made. They would also like to be able to
contribute back to OSM and in turn be able to reference the data from
OSM when it changes. There currently aren't any good methods to be able
to sync the data.
Alignment- FMMP data is slightly misaligned and appears to be off
when viewed with aerial photos or OSM data. FMMP is saved in NAD27 and
would need to be converted to WGS84. While the data is generally good,
it's almost as if the whole layer needs to be shifted slightly to make
it align. It could simply be a matter of the projection conversion.
Maybe there is another way to automatically convert it.
Crossing layers - Some layers may cut across a field that looks like
it should all be one area. FMMP classifies farm data as prime farmland,
farmland of statewide importance, farmland of local importance or unique
Lack of details - OSM is detailed when it comes to farms. There are
vineyards, orchards and farmland among some of the variations in farms.
FMMP makes no distinction between what the land is used for, with the
exception of grazing, which isn't useful in OSM because it is too
Existing data- Some counties such as Fresno, Kern and Santa Cruz
already have farm data imported on the parcel level. If the FMMP data
was added here, it would have to be combined with existing data.
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