[OKGIS] RE: UTM vs STATE PLANE

[Diane A Ayers]

I cannot answer the drive behind UTM being a standard for other data sets, 
but it was chosen for the data set I am currently working with (NYS Ag 
Districts boundary data) because it covers the entire state.  Typical tax 
parcel data is in state plane, but there are four zones for NYS.  UTM 
(extended zone 18) covers the whole state, so all the data is uniform.

Also, I think there is some confusion (or I have some confusion) between 
coordinate grid system and projection.  I believe that UTM and State Plane 
actually refer to the coordinate system used and that the projection (such 
as Albers) is another element of the data.  I am ever learning more on the 
subject, so I'm not sure I have it quite straight yet.....

The USGS has some great on-line info about different projections
http://erg.usgs.gov/isb/pubs/MapProjections/projections.html
http://erg.usgs.gov/isb/pubs/factsheets/fs08799.html