Digitizing

Digitizing is the procedure of taking coordinates from a registered image or scanned map, and creating a new vector data set.  It will generally be done "heads up" on the computer monitor, although historically it was done on special digitizing tablets.

Digitizing can be in two modes:

Digitizing depends on the user's hand eye coordination to accurately pick the correct points.  The accuracy depends on the scale of the map display, which limits the points you can select.  If the screen pixel size is 100 m, you will either have one pixel or its neighbor, and you maximum accuracy will be 100 m, or worse if you do not click on exactly the correct point.  Digitization should be done with map zoomed in as far as possible with the data available.  It benefits from the largest monitor available, and the map taking as much of the space as possible.

Digitizing probably requires a mouse, and would be very hard to perform with just a laptop trackpad.

 

Effects of digitizing mode.

  • A.  Point mode.  Note you can clearly see the individual points that the operator picked.
  • B.  Stream mode. The points are so close together you cannot see any gaps.
  • C.  Resulting lines.  Red is the point mode, and green is the stream mode.
 

Last revision 11/29/2017