Fingerprint identification is one of the richest tools available for the forensic examiner in a crime investigation, mainly because of its intrinsic characteristics of unicity and immutability. Among the various types of fingerprint found in crime scenes, latent fingerprints (that requires chemical and physical processes for their revelation) are the most used, given it’s high incidence in crime scenes and the existence of databases and automated computational systems for processing. However, the methods and techniques currently used as standards for revealing and collecting these latent vestiges ends up in the destruction of the original evidence, also requiring specific skills and materials, which has high cost and difficulty of access to many Forensic Institutes, like the Brazilian IGP. In addition, there is a negative influence of the physical (moisture) and chemical (organic and inorganic substances) characteristics of the surfaces during the revelation of latent fingerprints. In the current research, a prototype adaptable to a smartphone was developed, using a special light configuration to emphasizes the latent fingerprints. The system was able to obtain latent fingerprints on smooth surfaces in a practical, accessible and non-destructible way. However, the need for specific hardware equipped with other light options for different surfaces was observed. Results shows influence of different wavelengths and the positioning of the illumination on indoor and outdoor environments. As the research advances, we expect the system to become more solid, with the outcome of results more adequate to criminal investigation.
This paper presents a new configuration of an optical measurement system using fringe projection for 3D shape
measurement using active photogrammetry. The system was optimized to measure 3D geometries of external surfaces of
pipes. The system was mainly designed for periodic inspections of pipelines submitted to environmental induced
corrosion and local dents. It has a compact design and it is suitable to inspect pipes with diameters 250 mm (10”) and up.
The software is able to compute geometric parameters of the inspected area like depth, volume and length of the
damaged areas. The developed system uses a special compact fringe projector composed of an acrylic tube printed with
two sinusoidal fringe patterns with two different frequencies, a set of LEDs forming a line light source and a special
phase shifting approach with absolute phase calculation procedure. The three-dimensional surface of the pipe is
measured and displayed using virtual reality techniques. The measured area is 300 mm x 200 mm. The paper also
presents results of quantitative evaluations as well application results.