Tablet digitizers with a free cursor connected with a personal computer are the most common device for digitizing spatial features with the planimetric coordinates from analog maps. The analog map is placed on the surface of the digitizing tablet as shown in Figure 3.2. The size of digitizer usually ranges from A3 to A0 size.

The digitizing operation is as follows.
Step 1 : a map is affixed to a digitizing table.
Step 2 : control points or tics at four corners of this map sheet should be digitized by the digitizer and input to PC together with the map coordinates of the four corners.
Step 3 : map contents are digitized according to the map layers and map code system in either point mode or stream mode at short time interval.
Step 4 : editing errors such as small gaps at line junctions, overshoots, duplicates etc. should be made for a clean dataset without errors.
Step 5 : conversion from digitizer coordinates to map coordinates to store in a spatial database.

Major problems of map digitization are :
- the map will stretch or shrink day by day which makes the newly digitized points slightly off from the previous points.
- the map itself has errors
- discrepancies across neighboring map sheets will produce disconnectivity.

operators will make a lot of errors and mistakes while digitizing as shown in Figure 3.3.