Hello,
Earlier I made a post of scanning maps into GRASS. I have had
a lot of kind people respond.
Below is a snippet of what John Talcott instructed me to do:
I do this all the time, and it's not difficult once you get the hang of it.
I use the following procedure:
1) Since I use UTM coordinates, I mark UTM crosshair locations on the map
before I scan it. These pencil crosshairs will permit an accurate
registration later.
2) Scan the map at a resolution of at least 150 dpi and preferably 300 dpi.
This increases the accuracy of your registration and if you are going to
digitize anything after registration, it will increase the accuracy of
that, too. I store the scanned image as a tiff file.
The instructions include marking UTM coordinates on the map. I was wondering
if the following might be a way to accomplish this:
1) Purchase a topographical map(s)
2) Match chosen street intersections on the topographical map to
street intersections of the map that I wish to scan in.
3) Calculate the latitude and longitude (in degreees) of the
chosen street intersections
4) Convert lat and long coordinates to UTM coordinates
5) Apply UTM coordinates to the selected street intersections
of the map that I want to scan in.
Does this sound plausible? Am I missing something?
Any hints are appreciated
Thanks in advance
Casey
One must note the importance of setting reasonable and achievable goals for
"If you aim for nothing, you'll hit it every time"
-Theodore Roosevelt