3D view on the crossing lines problem in document investigation
Veerle Berx, Jan De Kinder · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2002
Optical examination, lifting techniques and electron microscopy are the most widely used methods for the determination of the writing order of crossing texts. Measuring the topography of the surface can provide additional information or determine the writing order where the common methods fail. Laser profilometry, as a non- contact technique, leaves the surface of the questioned documents unaltered. Several samples of crossing strokes, differing in writing pressure and support, were scanned. Depending on the type of support, a paper block or a metal surface, two phenomena were observed: the paper fibers are compressed and the line shows through. Despite of the complicating inhomogeneous structure of the paper, the writing sequence was determined unambiguously in the majority of the experiments. This makes laser profilometry a promising technique in fraud detection.