[GRASSLIST:4138] Map import cluelessness

[C.S. Cornuelle]

I am trying to import a scanned map into GRASS 5.3 and transform it into
the same coordinate system/projection as a grass database, e.g. a 
DEM in lat-lon.  

Having read the Spearfish tutorial and the Imagery tutorial, and having 
flailed away at my data, it occurs to me that I remain fairly 
clueless.  As I dimly understand it, one dumps the scanned map into 
a grass xy database.  Then i.group, i.target, and i.rectify are used
to transform this into a georeferenced database which is in the same
projection as the paper map, e.g. mercator.  Finally one would use 
r.proj to import this into the "target" database in which one really
wants to work, e.g. lat-lon.

Is that correct?

What I am not understanding is how to use i.target (or other tools) to 
achieve this.  Initially it seems that one would need to mark with
the cursor a location, e.g. a city, on the raw xy data, and then 
enter into the software the corresponding coordinates, e.g. latitude and
longitude, for the scanned map's actual projection, e.g. mercator.  But 
on the line

	Enter coordinates as east north:

I am unclear on what to enter.  It seems that one should just type in
the xy appearing on the screen, e.g.

	Point 2 marked on image at                 

	  East:     7342.50                        
	  North:    5578.50     

But how can this move things forward?  Should not i.target ask for the 
corresponding georeferenced coordinates, e.g. the latitude and longitude
of Mt. Olympus Utah USA?  Would not i.rectify need that information from
outside raw xy map in order to generate a new map, e.g. in the mercator
projection/coordinate system?  

Thanks for your patience, as I'm only a physicist and am easily
confused.  :^)

-- 
Adios,
Chris Cornuelle
bob at xmission dot com