[Imports] California farm data

Nathan Mixter 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. 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openstreetmap.org/pipermail/imports/attachments/20101024/23fa99d5/attachment.html>

More information about the Imports mailing list