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Digitizing is the process by which coordinates from a map, image, or other sources of data are converted into a digital format in a GIS.[1] This process becomes necessary when available data is gathered in formats that cannot be immediately integrated with other GIS data.

The Digitizing Process

A puck used in Manual Digitizing.
Manual Digitizing
In this method, the digitizer uses a digitizing tablet (also known as a digitizer, graphics tablet, or touch tablet) to trace the points, lines and polygons of a hard-copy map. This is done using a special magnetic pen, or stylus, that feeds information into a computer to create an identical, digital map. Some tablets use a mouse-like tool, called a puck, instead of a stylus. The puck has a small window with cross-hairs which allows for greater precision and pinpointing map features.[2]
Manual Digitizing is still a useful technique because of its ability to accurately copy maps in poor condition. Computers have a higher risk of error when interpreting information contained on a faded, stained, or poor quality map or image.[3] Manual Digitization is limited by the visual acuity and accuracy of the digitizer. The process ,also, is more time consuming than Heads-up digitizing.
Heads-up digitizing of building outlines performed in ArcMap10
Heads-up Digitizing
This method involves scanning a map or image into a computer. The digitizer then traces the points, lines and polygons using digitizing software. This method of digitizing has been named "heads-up" digitizing because the focus of the user is up on the screen, rather than down on a digitizing tablet.
It has largely replaced Manual digitizing because of its speed and accuracy. It is, however, limited to using scans of high quality maps and images. Since the tracing is done on a computer, lines can be set to snap together and polygons can be programmed to share an edge thus removing accidental sliver polygons. Heads-up digitizing also reduces or removes the need for digitizing tables.
Digitizing tips
  • Search for the digitized data first. Digitizing is very time consuming and often the data is already digitized.
  • Use multiple geographic sources when digitizing. Referencing such sources as scanned topographical maps, orthophotos, remotely sensed data, and in situ data will increase the accuracy of the digitized data.

See also


  1. Paul Bolstad (2008). GIS Fundamentals:A First Text on Geographic Information Systems. Page 132
  2. Webopedia (2013). Digitizing tablet.[1]
  3. Paul Bolstad (2008). GIS Fundamentals:A First Text on Geographic Information Systems. Page 136