Reducing the False Positive Rate Using Bayesian Inference in Autonomous Driving Perception

Object recognition is a crucial step in perception systems for autonomous and intelligent vehicles, as evidenced by the numerous research works in the topic. In this paper, object recognition is explored by using multisensory and multimodality approaches, with the intention of reducing the false positive rate (FPR). The reduction of the FPR becomes increasingly important in perception systems since the misclassification of an object can potentially cause accidents. In particular, this work presents a strategy through Bayesian inference to reduce the FPR considering the likelihood function as a cumulative distribution function from Gaussian kernel density estimations, and the prior probabilities as cumulative functions of normalized histograms. The validation of the proposed methodology is performed on the KITTI dataset using deep networks (DenseNet, NasNet, and EfficientNet), and recent 3D point cloud networks (PointNet, and PintNet++), by considering three object-categories (cars, cyclists, pedestrians) and the RGB and LiDAR sensor modalities.Comment: This paper has been submitted to the journal Pattern Recognition Letter

Técnicas multivariadas para detecção das respostas auditivas em regime permanente

Exportado OPUSMade available in DSpace on 2019-08-12T20:19:10Z (GMT). No. of bitstreams: 1 mestrado_tiago_zanotelli_final.pdf: 1233213 bytes, checksum: edcb5120523ba162b13715fbadcf0f42 (MD5) Previous issue date: 21A Resposta Auditiva em Regime Permanente (ASSR) é um potencial eliciado no córtex devido a uma estimulação rápida o suficiente para que a resposta a um dado estímulo sobreponha à resposta do estímulo seguinte. A detecção da ASSR tem sido utilizada na estimação de um perfil audiométrico fisiológico abrangente, principalmente em indivíduos que não podem responder aos exames convencionais. Técnicas univariadas de detecção objetiva (ORD) que utilizam informação de energia (Teste Espectral F), fase (Medida de Sincronismo de Componente - CSM) e coerência (Magnitude Quadrática da Coerência - MSC) têm sido utilizadas para identificar a ASSR. Um dos problemas do exame de ASSR é a sua duração, entre 45 e 60 minutos. A presente dissertação tem por objetivo investigar a utilização de técnicas ORD Multivariadas (MORD) para detectar a ASSR com tons AM, visando reduzir o tempo de sua detecção. As técnicas MORD utilizadas foram: a Medida de Sincronismo de Componente Múltipla (MCSM) e a Magnitude Quadrática da Coerência Múltipla (MMSC). Os sinais de EEG foram coletados de oito (8) indivíduos saudáveis em F3, F4, Fz, C3, C4, Cz, P3, P4, Pz, T3, T4 e Oz durante duas sessões de 16 minutos de estimulação auditiva com intensidades de 60 e 40 dB SPL. Em cada sessão, apresentou-se simultaneamente na orelha esquerda e na direita um estímulo constituído por quatro tons AM portadoras de 0,5, 1, 2 e 4 kHz para ambas as orelhas e modulantes de 78, 83, 88, 92 Hz para a orelha direita e 81, 85, 90, 95 Hz para a esquerda. Os resultados mostraram que, com a utilização das técnicas de MORD com cinco canais, é possível reduzir o tempo de detecção da ASSR em até 25,15% (MMSC) em relação às técnicas ORD (MSC). Assim, as técnicas de MORD se apresentam como uma ferramenta promissora, para detecção da ASSR, podendo ser utilizada para reduzir o tempo da obtenção dos limiares fisiológicos auditivos.Auditory Steady-State Response (ASSR) is a potential elicited in the brain due to stimulation rapid stimulation enough that the response to a given stimulus overlaps the response the next stimulus. Detection of ASSR has been used to estimate a physiological audiometric, especially in individuals who do not respond to conventional tonal exam. Multivariate techniques of Objective Response Detection (ORD) which use energy information (F Spectral Test), phase (Component Synchrony Measure CSM) and coherence (Magnitude Square Coherence MSC) have been used to identify ASSR. One of the problems of the ASSR exam is its duration, which varies from 45 to 60 minutes. The present dissertation aims to investigate the use of Multivariate ORD (MORD) to detect ASSR with AM tones, to reduce detection time. The MORD techniques used were: Multiple Component Synchrony Measure (MCSM) and Multiple Magnitude Squared Coherence (MMSC). The EEG signals were collected from eight (8) healthy volunteers in F3, F4, Fz, C3, C4, Cz, P3, P4, Pz, T3, T4 and Oz during two sessions of 16 minutes stimulation with intensities of 60 and 40 dB SPL. In each session, a stimulus was presented simultaneously on the left and right ears composed of 4 AM tones carriers of 0.5, 1, 2 and 4 kHz for both ears and modulated, respectively, at 78, 83, 88 and 92 Hz for the right ear and 81, 85, 90 and 95 Hz for the left. Results showed that the use of MORD techniques with 5 channels can reduce ASSR detection time in up to 25.15% (MMSC) compared to the ORD techniques (MSC). Thus, MORD techniques were seen as a promising tool, for ASSR detection, and can be used to reduce acquirement times for physiological auditory threshold

Faster automatic ASSR detection using sequential tests

Objective: Objective Response Detection (ORD) can be used for auditory steady-state response (ASSR) detection. In conventional ORD methods, the statistical tests are applied at the end of data collection (‘single-shot tests’). In sequential ORD methods, statistical tests are applied repeatedly, while data is being collected. However, repeated testing can increase False Positive (FP) rates. One solution is to infer that response is present only after the test remains significant for a predefined number of consecutive detections (NCD). Thus, this paper describes a new method for finding the required NCD that control the FP rate for ASSR detection. Design: NCD values are estimated using Monte Carlo simulations. Study sample: ASSR signals were recorded from 8 normal-hearing subjects. Results: The exam time was reduced by up to 38.9% compared to the single-shot test with loss of approximately 5% in detection rate. Alternatively, lower gains in time were achieved for a smaller (non-significant) loss in detection rate. The FP rates at the end of the test were kept at the nominal level expected (1%). Conclusion: The sequential test strategy with NCD as the stopping criterion can improve the speed of ASSR detection and prevent higher than expected FP rates