[GRASSLIST:1627] Re: More projection problems...

[Eric G. Miller]

On Fri, Mar 16, 2001 at 05:59:43PM -0800, Eric G. Miller wrote:
> > If any one can give me a handle on what I am doing wrong I would
> > appreciate it.
> > 
> > I would also like to thank the 4 or 5 people who have helped me get
> > rolling with grass. The docs are pretty good, but the people here make
> > this thing work.
> 
> I don't know if this is the source of the problem, but I tried out
> defining a State Plane for Florida/Marion using nad83/grs80, but it
> still culls the projection parameters for the nad27/clark66.  Unless I'm
> mistaken, you want the NAD83 State Plane for Florida???  However, the
> state plane interface for GRASS doesn't seem to let one decide.  Also,
> should the output units be meters as well?  I never use this State Plane
> thingy...
> 
> There are significant differences in the false easting between stp27 and
> stp83.  The difference in just false easting, not accounting for other
> variables is roughly 157440 feet (converted from the x_0 parameter
> which is in meters) -- close to your 120000.
> 
> The state27 and state83 files live in grass5/etc if you want a look.  It
> won't help you much though...

To follow up:  If this is the source of the problem (and I think it just
might be), just replace the values in your PERMANENT/PROJ_INFO file,
with the correct ones from the state83 file.  Seems Florida has three
zones, so you'll have to figure out which one to use (ahh, it's in the
FIPS.code file -- number 902 for Marion).

-- 
Eric G. Miller <egm2 at jps.net>