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Denoising the point cloud is fundamental for reconstructing high quality surfaces with details in order to eliminate noise and outliers in the 3D scanning process. The challenges for a denoising algorithm are noise reduction and sharp features preservation. In this paper, we present a new model to reconstruct and smooth point clouds that combine L1-median filtering with sparse L1 regularization for both denoising the normal vectors and updating the position of the points to preserve sharp features in the point cloud. The L1-median filter is robust to outliers and noise compared to the mean. The L1 norm is a way to measure the sparsity of a solution, and applying an L1 optimization to the point cloud can measure the sparsity of sharp features, producing clean point set surfaces with sharp features. We optimize the L1 minimization problem by using the proximal gradient descent algorithm. Experimental results show that our approach is comparable to the state-of-the-art methods, as it filters out 3D models with a high level of noise, but keeps their geometric features.

According to worldwide statistics, traffic accidents are the cause of a high percentage of violent deaths. The time taken to send the medical response to the accident site is largely affected by the human factor and correlates with survival probability. Due to this and the wide use of video surveillance and intelligent traffic systems, an automated traffic accident detection approach becomes desirable for computer vision researchers. Nowadays, Deep Learning (DL)-based approaches have shown high performance in computer vision tasks that involve a complex features relationship. Therefore, this work develops an automated DL-based method capable of detecting traffic accidents on video. The proposed method assumes that traffic accident events are described by visual features occurring through a temporal way. Therefore, a visual features extraction phase, followed by a temporary pattern identification, compose the model architecture. The visual and temporal features are learned in the training phase through convolution and recurrent layers using built-from-scratch and public datasets. An accuracy of 98% is achieved in the detection of accidents in public traffic accident datasets, showing a high capacity in detection independent of the road structure.

Objetivo: Diseñar y desarrollar un modelo de simulación de eventos discretos para el proceso de atención del cliente de una Pyme dedicada al negocio de la comida rápida con el fin de conducir experimentos direccionados a comprender el comportamiento del sistema y evaluar estrategias de optimización. Metodología: El procedimiento se clasifica en cuatro etapas: (I) Análisis de la empresa y definición del problema, (II) Descripción de procesos y contextualización de un modelo, (III) Generación del modelo preliminar, verificación, validación y análisis de sensibilidad, (IV) Análisis de resultados y propuestas de mejoramiento. Resultados: El modelamiento realizado permitió sugerir una serie de optimizaciones para los procesos y de la Pyme analizada, que resultarían en la reducción de los tiempos de espera en la venta de bebidas, pizzas y otros productos.  Conclusiones: Se mostró que mediante herramientas como Simul8® es posible modelar con facilidad procesos, al igual que sugerir optimizaciones pertinentes para estos, si bien cabe anotar que la herramienta no es tan efectiva para el modelamiento de servicios.

In recent years, the use of deep learning-based models for developing advanced healthcare systems has been growing due to the results they can achieve. However, the majority of the proposed deep learning-models largely use convolutional and pooling operations, causing a loss in valuable data and focusing on local information. In this paper, we propose a deep learning-based approach that uses global and local features which are of importance in the medical image segmentation process. In order to train the architecture, we used extracted three-dimensional (3D) blocks from the full magnetic resonance image resolution, which were sent through a set of successive convolutional neural network (CNN) layers free of pooling operations to extract local information. Later, we sent the resulting feature maps to successive layers of self-attention modules to obtain the global context, whose output was later dispatched to the decoder pipeline composed mostly of upsampling layers. The model was trained using the Mindboggle-101 dataset. The experimental results showed that the self-attention modules allow segmentation with a higher Mean Dice Score of 0.90 ± 0.036 compared with other UNet-based approaches. The average segmentation time was approximately 0.038 s per brain structure. The proposed model allows tackling the brain structure segmentation task properly. Exploiting the global context that the self-attention modules incorporate allows for more precise and faster segmentation. We segmented 37 brain structures and, to the best of our knowledge, it is the largest number of structures under a 3D approach using attention mechanisms.

High-resolution 3D scanning devices produce high-density point clouds, which require a large capacity of storage and time-consuming processing algorithms. In order to reduce both needs, it is common to apply surface simplification algorithms as a preprocessing stage. The goal of point cloud simplification algorithms is to reduce the volume of data while preserving the most relevant features of the original point cloud. In this paper, we present a new point cloud feature-preserving simplification algorithm. We use a global approach to detect saliencies on a given point cloud. Our method estimates a feature vector for each point in the cloud. The components of the feature vector are the normal vector coordinates, the point coordinates, and the surface curvature at each point. Feature vectors are used as basis signals to carry out a dictionary learning process, producing a trained dictionary. We perform the corresponding sparse coding process to produce a sparse matrix. To detect the saliencies, the proposed method uses two measures, the first of which takes into account the quantity of nonzero elements in each column vector of the sparse matrix and the second the reconstruction error of each signal. These measures are then combined to produce the final saliency value for each point in the cloud. Next, we proceed with the simplification of the point cloud, guided by the detected saliency and using the saliency values of each point as a dynamic clusterization radius. We validate the proposed method by comparing it with a set of state-of-the-art methods, demonstrating the effectiveness of the simplification method.

La fusión de imágenes genera una imagen  que combina las características más relevantes de un conjunto de imágenes de la misma escena adquiridas con diferentes cámaras o configuraciones. La Fusión de Imágenes Multifoco (MFIF) parte de un conjunto de imágenes con diferente distancia focal para generar una imagen  con una profundidad de campo extendida. Lo que constituye una solución al problema de la profundidad de campo limitada en la configuración de un sistema óptico. La literatura muestra una amplia variedad de trabajos que abordan este problema. Las transformaciones de dominios y el análisis de bloques de píxeles son la base de los principales enfoques propuestos. En este trabajo se presenta una evaluación de diferentes sistemas de aprendizaje supervisado aplicados a MFIF, incluyendo k-vecinos más cercanos, análisis discriminante lineal, redes neuronales y máquinas de soporte vectorial. El método inicia con dos imágenes de la misma escena, pero con diferentes distancias focales que se dividen en regiones rectangulares. El objetivo principal del sistema de clasificación, que está basado en aprendizaje de máquina, es elegir las partes de ambas imágenes que deben estar en la imagen fusionada para obtener una imagen completamente enfocada. Para la cuantificación del enfoque se utilizaron las métricas más populares propuestas en la literatura como: la Energía Laplaciana, el Laplaciano Modificado por Suma y el Gradiente de Energía, entre otras. La evaluación del método propuesto incluye la fase de prueba de los clasificadores y las métricas de calidad de fusión utilizadas comúnmente en la investigación, tales como la fidelidad de la información visual y la característica de información mutua. Los resultados muestran que el concepto de clasificación automática puede abordar satisfactoriamente el problema MFIF.

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