----------------------------Original message----------------------------
>
> ----------------------------Original message----------------------------
> Has anyone done anything with using a UTM projection outside of its prescribed
> zone (i.e. study areas that cross zone boundaries)?  I will be doing some work
> looking at the resultant distortion and was wondering if anyone else had
> already done anything.
>
Brandon,
 
I done this, and it will work, but as you get further from the central
meridian, the distortion will increase in a non-linear fashion.  If your
study area spans regions in more than one zone, why not just use plain old
Transverse Mercator and choose the center of your map as the central
meridian?  The only thing that differentiates UTM from TM is the choice of
a central meridian and a scale factor along the CM (UTM is .9996 instead of
1, I believe).
 
If your study region spans more than two UTM zones, then I really think you
should reconsider your choice of projection.  At best, your map will not
really be useful to users; at worst, the computer will freak out with
rounding errors, and it will be just plain wrong.
 
- Bill Thoen
  [log in to unmask]