RECONHECIMENTO BIOMÉTRICO NEGATIVO

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Biometric recognition in unconstrained environments

Publication . Santos, Gil Melfe Mateus; Proença, Hugo Pedro Martins Carriço

Every human being is entitled, by his very nature, to a set of physiological and behavioral features that characterize him. The study of such features led to the development of a considerable amount of systems and applications, referred as biometric systems. The use of biometric systems has been significantly growing over the last years, particularly in the field of security: authentication, access control, criminal identification, etc. Being a highly demanding sector, it is then natural that greater focus is placed on the biometric traits that are able to deliver high discrimination between subjects whilst being less prone to forgery. However, such constraints represent a significant impact on both system’s usability and flexibility, requiring from the user a significant amount of cooperation. In this context, the iris is a primordial trait. Existing biometric recognition systems based on the iris follow the pioneer approach proposed by John Daugman, that proved itself as an excellent option for cooperative scenarios where images are acquired in the near-infrared spectrum. However, not in every case user cooperation is expected and, when not, systems with such high acquisition constraints are of little or no use. Research is then focused on circumventing those issues, either by improving the existing methods or finding new and more fitting traits. On the later, the periocular region (i.e., the region surrounding the eye) is one of the most promising characteristics: it mimics a natural and spontaneous way of recognition employed by the human beings; has an advantageous localization in relation to the iris, making it easy to be simultaneously acquired; and has, as corroborated by the literature, a set of promising characteristics that can be used for recognition purposes. The main objective of this doctoral work is then to either adapt or develop a novel biometric recognition system, suited for in the wild environments. Such systems should preferably use the periocular region as biometric trait, due to its flexibility and ease of acquisition in adverse conditions, and keep the operation constraints as low as possible. Subjects can be imaged ata- distance, on-the-move, and under irregular lighting conditions, using cameras working in the visible wavelength. To accomplish such goal, a set of intermediate milestones was established. At first, the iris was studied as biometric trait, paying particular attention to the techniques for allowing its use on in the wild scenarios. The effects of the visible wavelength light on iris performance for biometric purposes should not be disregarded and, as so, this factor was also studied. After rolling out iris appropriateness as the main distinctive feature, different emerging traits were analyzed, with special attention being paid to the periocular region. The most relevant methods were implemented and tested against the same dataset. Ultimately, multiple contributions were proposed and accepted by the scientific community, with applicability on different in the wild environments, the last of which is the proposal of an actual biometric system, working in real challenging conditions.

2015-04Doctoral thesis

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