Methods for data-related problems in person re-ID

In the last years, the ever-increasing need for public security has attracted wide attention in person re-ID. State-of-the-art techniques have achieved impressive results on academic datasets, which are nearly saturated. However, when it comes to deploying a re-ID system in a practical surveillance scenario, several challenges arise. 1) Full person views are often unavailable, and missing body parts make the comparison very challenging due to significant misalignment of the views. 2) Low diversity in training data introduces bias in re-ID systems. 3) The available data might come from different modalities, e.g., text and images. This thesis proposes Partial Matching Net (PMN) that detects body joints, aligns partial views, and hallucinates the missing parts based on the information present in the frame and a learned model of a person. The aligned and reconstructed views are then combined into a joint representation and used for matching images. The thesis also investigates different types of bias that typically occur in re-ID scenarios when the similarity between two persons is due to the same pose, body part, or camera view, rather than to the ID-related cues. It proposes a general approach to mitigate these effects named Bias-Control (BC) framework with two training streams leveraging adversarial and multitask learning to reduce bias-related features. Finally, the thesis investigates a novel mechanism for matching data across visual and text modalities. It proposes a framework Text (TAVD) with two complementary modules: Text attribute feature aggregation (TA) that aggregates multiple semantic attributes in a bimodal space for globally matching text descriptions with images and Visual feature decomposition (VD) which performs feature embedding for locally matching image regions with text attributes. The results and comparison to state of the art on different benchmarks show that the proposed solutions are effective strategies for person re-ID.Open Acces

Subspace-Based Holistic Registration for Low-Resolution Facial Images

Subspace-based holistic registration is introduced as an alternative to landmark-based face registration, which has a poor performance on low-resolution images, as obtained in camera surveillance applications. The proposed registration method finds the alignment by maximizing the similarity score between a probe and a gallery image. We use a novel probabilistic framework for both user-independent as well as user-specific face registration. The similarity is calculated using the probability that the face image is correctly aligned in a face subspace, but additionally we take the probability into account that the face is misaligned based on the residual error in the dimensions perpendicular to the face subspace. We perform extensive experiments on the FRGCv2 database to evaluate the impact that the face registration methods have on face recognition. Subspace-based holistic registration on low-resolution images can improve face recognition in comparison with landmark-based registration on high-resolution images. The performance of the tested face recognition methods after subspace-based holistic registration on a low-resolution version of the FRGC database is similar to that after manual registration

A study of deep learning and its applications to face recognition techniques

El siguiente trabajo es el resultado de la tesis de maestría de Fernando Suzacq. La tesis se centró alrededor de la investigación sobre el reconocimiento facial en 3D, sin la reconstrucción de la profundidad ni la utilización de modelos 3D genéricos. Esta investigación resultó en la escritura de un paper y su posterior publicación en IEEE Transactions on Pattern Analysis and Machine Intelligence. Mediante el uso de iluminación activa, se mejora el reconocimiento facial en 2D y se lo hace más robusto a condiciones de baja iluminación o ataques de falsificación de identidad. La idea central del trabajo es la proyección de un patrón de luz de alta frecuencia sobre la cara de prueba. De la captura de esta imagen, nos es posible recuperar información real 3D, que se desprende de las deformaciones de este patrón, junto con una imagen 2D de la cara de prueba. Este proceso evita tener que lidiar con la difícil tarea de reconstrucción 3D. En el trabajo se presenta la teoría que fundamenta este proceso, se explica su construcción y se proveen los resultados de distintos experimentos realizados que sostienen su validez y utilidad. Para el desarrollo de esta investigación, fue necesario el estudio de la teoría existente y una revisión del estado del arte en este problema particular. Parte del resultado de este trabajo se presenta también en este documento, como marco teórico sobre la publicación