Experimental Analysis of in-Air Trajectories at Long Distances in Online Handwriting

In this paper, we analyze in-air movements in online handwriting databases when the distance from the tip of the pen to the paper surface is higher than 1 cm. In this case, the computer can only know the time spent in air because the distance is too high to track the x and y coordinates of the movement. While this kind of movement is usually discarded, some investigation must be done in order to decide if computational algorithms can take advantage of this information in some scenarios. In this paper, we establish a criterion to differentiate useful in-air long distance strokes from user pauses.