scanning maps

Casey Claiborne mskc at
Fri Nov 10 07:00:00 EST 1995

        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


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

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