A Study To Determine The Sequence Of Intersecting Laser Printed And Pen Strokes Based On 3D Features

Determining the sequence of intersecting printed and pen strokes is of great significance to the examination of added and modified documents.Generally speaking,the normal sequence of document formation is to print first and then write.If writing is before printing,the document is likely to be added or modified.Recently,with the development of 3D measurement technology,3D measurement becomes possible.Therefore,this paper aims to investigate the sequence of intersecting laser printed and pen strokes based on 3D features.It contains 5 parts as follows:The introduction part contains value of the theme,literature review,research methods,structure,innovations and deficiencies of this paper.In the literature review,it reviews the application of 3D features in the examination of questioned documents and the methods of determining the sequence of intersecting strokes.Besides the advantages and disadvantages of each method are evaluated.It helps to point out the direction for the study of the sequence of intersecting laser printed and pen strokes based on 3D features.The first chapter is a theoretical overview of determining the sequence of intersecting laser printed and pen strokes based on 3D features.In this chapter,the theory and measurement methods of 3D features are summarized.Besides,The chapter also discusses the mechanism of printing as well as handwriting.Through the above theoretical overview,the foundation for the follow-up study is laid.The second chapter is the experimental plan to investigate the sequence of intersecting laser printed and pen strokes.It includes the material and process of sample preparation,overview of experimental equipment as well as the experimental process.The third chapter is the experimental results.The whole chapter consists three sections.The first section is to determine the sequence of intersecting laser printed and pen strokes based on 2D features.It shows that the specular reflection,the ink glosses,gap and scratch are able to determine the sequence of intersecting strokes.The second section is to determine the sequence of intersecting laser printed and pen strokes based on 3D features.Three types of samples intersected with ballpoint pen strokes,fountain pen strokes and fiber pen strokes are investigated respectively based on 3D pseudo color image,contour measurement,average height measurement and surface roughness measurement.Furthermore,it continues to investigate the influence of printing thickness,writing pressure and underlays.The third section is the comparison of determining the sequence of intersecting laser printed and pen strokes based on 2D features and 3D features.It compares the test accuracy of the two methods.The fourth chapter is the conclusion and prospect.It concludes the whole study and points out the effective methods to determine the sequence of intersecting laser printed and pen strokes.In the end,it prospects the application of 3D features to other objects of questioned document examination.