The Application of Profilometry in the Analysis of the Lines Crossing

A new approach for the problem of lines crossing was developed in this research project: laser profilometry was applied to crossing texts on questioned documents to determine the sequence of writing. Four major parameters influenced the presence of the crossing lines: the pressure exerted during the writing process, the kind of writing material and thus the kind of ink deposits, the type of paper used, and the angle between the crossing texts. In this paper, the writing pressure of both lines, together with the substrate (soft or hard), was controlled and varied through the tests. Homogeneous as well as heterogeneous writing pressures were evaluated. For the majority of the samples, 3-D topography gave conclusive information about the writing order, based on the presence of a complete intersection of 1 of the lines or an oval impression in the direction of the last-applied stroke. This research makes the laser profilometry a promising technique for questioned document examination.