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Creating Digital Maps Using the Digitizer in Room 406 Williams Hall

written by Cliff Buck

This method is more complicated but yields more accurate results when done correctly. The procedure is as follows:

Arc>digest 9100/dev/ttyf1 (follow on-screen directions)

Arc>ae (enter ArcEdit)

ArcEdit>digitizer 9100/dev/ttyf1

ArcEdit>coordinate digitizer default

ArcEdit>display 9999

ArcEdit> create <cover>

(At this point, enter at least four tics in a clockwise pattern at points that are easily identifiable, ie major road intersections. Four is the minimum but using more tics will make the map more accurate after transformation. Record the coordinates of these tics for use later during transformation.)

ArcEdit> ef arc

ArcEdit> intersectarcs all

ArcEdit> add

(This will bring up a menu listing commands for the digitizer. Trace the desired arc on the paper map. Press 9 on the digitizer when done.)

ArcEdit> de node errors

ArcEdit> draw (All node errors will be marked with squares)

ArcEdit> coordinate mouse (Makes the mouse active)

(Edit the node errors using the following table of commands, other commands may be found in the ArcEdit help book.)

Problem

Command

Undershoot

Select, Extend

Overshoot (Dangle)

Select, Delete

Other

Vertex Move, Vertex Delete

ArcEdit> build

ArcEdit> save

ArcEdit> quit

Arc> create <new cover> (This will be the name of the coverage after transformation.)

Arc> info

ArcInfo> SEL <NEW COVER>.TIC

ArcInfo> ADD

(Enter the coordinates of the tics.)

ArcInfo> Q STOP

Arc> transform <cover> <new cover> (This command will transform the coverage from table units to units corresponding to the units of the map.)

Arc> build <new cover>