Range Image Sampling in Orientation Variation Space

La información proveniente de un conjunto de imágenes de rango puede utilizarse para producir modelos computacionales en 3D de la escena. Sin embargo, cada imagen esta referida a las coordenadas de la cámara en el momento de la adquisición. Encontrar un conjunto de transformaciones tales que, aplicadas a las imágenes, lleven el conjunto a un sistema coordenado común, es usualmente denominado registro de imágenes de rango. Uno de los grandes problemas en dicho proceso está relacionado con datos seleccionados de forma arbitraria y que no son relevantes en el registro. En éste artículo se propone un nuevo método de muestreo, basado en el uso de la información local de variación de la orientación (curvatura). Se muestra que, el rendimiento del algoritmo es adecuado en comparación con las técnicas habituales en la reconstrucción de modelos a partir de imágenes de rango.Palabras claves: Imágenes de rango, métodos de muestreo, registro.The information provided by a set of range images can be used in order to produce a computational 3D model of the scene. However, each image is refered to the camera coordinates at its acquisition. To fi nd a set of transformations that takes the whole set into a common coordinate system is what we usually call range images registration. One of the mayor problems of this process is produced by arbitrary data that is not relevant for the registration. In this paper I propose a new method of data sampling in which local variation in orientation (curvature) is used. I show that the proposed algorithm performs well against the ones typically used in model reconstruction from range images

Muestreo de imágenes de rango en el espacio de variación de la orientación

La información proveniente de un conjunto de imágenes de rango puede utilizarse para producir modelos computacionales en 3D de la escena. Sin embargo, cada imagen esta referida a las coordenadas de la cámara en el momento de la adquisición. Encontrar un conjunto de transformaciones tales que, aplicadas a las imágenes, lleven el conjunto a un sistema coordenado común, es usualmente denominado registro de imágenes de rango. Uno de los grandes problemas en dicho proceso está relacionado con datos seleccionados de forma arbitraria y que no son relevantes en el registro. En éste artículo se propone un nuevo método de muestreo, basado en el uso de la información local de variación de la orientación (curvatura). Se muestra que, el rendimiento del algoritmo es adecuado en comparación con las técnicas habituales en la reconstrucción de modelos a partir de imágenes de rango.Palabras claves: Imágenes de rango, métodos de muestreo, registro

Dos agentes con algoritmos GBFS trabajando de forma cooperativa para obtener la ruta más corta

This study is carried out in order to verify if the implementation of the concept of cooperative work among two agents, that use path planners A* to obtain the shortest path (previous work of the authors) is also valid when the cooperative strategy is applied using another path planner such as the so-called GBFS (Greedy Best First Search). In this sense, this paper shows a path planning strategy that combines the capabilities of two Agents each one with its own path planner GBFS (slightly different from each other) in order to obtain the shortest path. The comparisons between paths are made by analyzing the behavior and results obtained from the agents operating in different forms: (1) Working individually; (2) Working as a team (cooperating and exchanging information). The results show that in all analyzed situations are obtained shortest traveled distances when the path planners work as a cooperative team.Este estudio se lleva a cabo con el fin de verificar si la implementación del concepto de trabajo cooperativo entre dos agentes, usado con planificadores A* para obtener la ruta más corta (trabajo previo de los autores) también es válida cuando la estrategia cooperativa es aplicada usando otro planificador de rutas como el llamado GBFS (Greedy Best First Search). En este sentido, el articulo muestra una estrategia de planificación de rutas que combina las capacidades de dos agentes cada uno con su propio planificador de rutas GBFS (ligeramente diferentes entre sí) para obtener la ruta más corta. La comparación entre las dos rutas se realiza analizando el comportamiento y comparando los resultados obtenidos para cada uno de los que operan en diferentes formas: (1) Trabajando individualmente; (2) Trabajando como un equipo (cooperando e intercambiando información). Los resultados muestran que para todos los casos analizados se obtiene la distancia recorrida más corta cuando los planificadores de ruta trabajan como un equipo colaborativo

Dos agentes con algoritmos GBFS trabajando de forma cooperativa para obtener la ruta más corta

This study is carried out in order to verify if the implementation of the concept of cooperative work among two agents, that use path planners A* to obtain the shortest path (previous work of the authors) is also valid when the cooperative strategy is applied using another path planner such as the so-called GBFS (Greedy Best First Search). In this sense, this paper shows a path planning strategy that combines the capabilities of two Agents each one with its own path planner GBFS (slightly different from each other) in order to obtain the shortest path. The comparisons between paths are made by analyzing the behavior and results obtained from the agents operating in different forms: (1) Working individually; (2) Working as a team (cooperating and exchanging information). The results show that in all analyzed situations are obtained shortest traveled distances when the path planners work as a cooperative team.Este estudio se lleva a cabo con el fin de verificar si la implementación del concepto de trabajo cooperativo entre dos agentes, usado con planificadores A* para obtener la ruta más corta (trabajo previo de los autores) también es válida cuando la estrategia cooperativa es aplicada usando otro planificador de rutas como el llamado GBFS (Greedy Best First Search). En este sentido, el articulo muestra una estrategia de planificación de rutas que combina las capacidades de dos agentes cada uno con su propio planificador de rutas GBFS (ligeramente diferentes entre sí) para obtener la ruta más corta. La comparación entre las dos rutas se realiza analizando el comportamiento y comparando los resultados obtenidos para cada uno de los que operan en diferentes formas: (1) Trabajando individualmente; (2) Trabajando como un equipo (cooperando e intercambiando información). Los resultados muestran que para todos los casos analizados se obtiene la distancia recorrida más corta cuando los planificadores de ruta trabajan como un equipo colaborativo

Estimating Acceleration from a Single Uniform Linear Motion-Blurred Image using Homomorphic Mapping and Machine Learning

Context:  Vision-based measurement (VBM) systems are becoming popular as an affordable and suitable alternative for scientific and engineering applications. When cameras are used as instruments, motion blur usually emerges as a recurrent and undesirable image degradation, which in fact contains kinematic information that is usually dismissed. Method: This paper introduces an alternative approach to measure relative acceleration from a real invariant uniformly accelerated linear motion-blurred image. This is done by using homomorphic mapping to extract the characteristic Point Spread Function (PSF) of the blurred image, as well as machine learning regression. A total of 125 uniformly accelerated motion-blurred pictures were taken in a light- and distance-controlled environment, at five different accelerations ranging between 0,64 and 2,4 m/s2. This study evaluated 19 variants such as tree ensembles, Gaussian processes (GPR), and linear, support vector machine (SVM), and tree regression. Results: The best RMSE result corresponds to GPR (Matern 5/2), with 0,2547 m/s2 and a prediction speed of 530 observations per second (obs/s). Additionally, some novel deep learning methods were used to obtain the best RMSE value (0,4639 m/s2 for Inception ResNet v2, with a prediction speed of 11 obs/s. Conclusions: The proposed method (homomorphic mapping and machine learning) is a valid alternative for calculating acceleration from invariant motion blur in real-time applications when additive noise is not dominant, even surpassing the deep learning techniques evaluated

Revista Colombiana de Computación. Volumen 7 Número 2 Diciembre de 2006

Tenemos la satisfacción de presentar a la comunidad académica el último número del año 2006 de la Revista Colombiana de Computación. Continuamos recibiendo artículos de diferentes países del mundo, de gran calidad, como los que se publican en este número.We are pleased to present to the academic community the last issue of 2006 of the Revista Colombiana de Computación. We continue to receive articles from different countries around the world, of great quality, such as those published in this issue

Guía Mexicana para el Diagnóstico y el Tratamiento de la Urticaria

La urticaria es una enfermedad que padece una quinta parte de la población en algún momento de su vida. Las guías inter- nacionales recientes han propuesto unos cambios de fondo en su diagnóstico y tratamiento, por lo que había la necesidad de crear una guía nacional y multidisciplinaria, con base amplia en los gremios de especialistas y médicos de primer contacto en México. ABSTRACT Urticaria is a disease that a fifth of the population shall suffer once in a lifetime. Recent clinical guidelines have proposed some fundamental changes in the diagnosis and treatment of urticaria, making the development of a national, multidisciplinary guideline, with wide acceptability among different professional groups –both specialists and primary health care workers–, necessary in Mexico

Geographic patterns of tree dispersal modes in Amazonia and their ecological correlates

Aim: To investigate the geographic patterns and ecological correlates in the geographic distribution of the most common tree dispersal modes in Amazonia (endozoochory, synzoochory, anemochory and hydrochory). We examined if the proportional abundance of these dispersal modes could be explained by the availability of dispersal agents (disperser-availability hypothesis) and/or the availability of resources for constructing zoochorous fruits (resource-availability hypothesis). Time period: Tree-inventory plots established between 1934 and 2019. Major taxa studied: Trees with a diameter at breast height (DBH) ≥ 9.55 cm. Location: Amazonia, here defined as the lowland rain forests of the Amazon River basin and the Guiana Shield. Methods: We assigned dispersal modes to a total of 5433 species and morphospecies within 1877 tree-inventory plots across terra-firme, seasonally flooded, and permanently flooded forests. We investigated geographic patterns in the proportional abundance of dispersal modes. We performed an abundance-weighted mean pairwise distance (MPD) test and fit generalized linear models (GLMs) to explain the geographic distribution of dispersal modes. Results: Anemochory was significantly, positively associated with mean annual wind speed, and hydrochory was significantly higher in flooded forests. Dispersal modes did not consistently show significant associations with the availability of resources for constructing zoochorous fruits. A lower dissimilarity in dispersal modes, resulting from a higher dominance of endozoochory, occurred in terra-firme forests (excluding podzols) compared to flooded forests. Main conclusions: The disperser-availability hypothesis was well supported for abiotic dispersal modes (anemochory and hydrochory). The availability of resources for constructing zoochorous fruits seems an unlikely explanation for the distribution of dispersal modes in Amazonia. The association between frugivores and the proportional abundance of zoochory requires further research, as tree recruitment not only depends on dispersal vectors but also on conditions that favour or limit seedling recruitment across forest types

Geography and ecology shape the phylogenetic composition of Amazonian tree communities

Aim: Amazonia hosts more tree species from numerous evolutionary lineages, both young and ancient, than any other biogeographic region. Previous studies have shown that tree lineages colonized multiple edaphic environments and dispersed widely across Amazonia, leading to a hypothesis, which we test, that lineages should not be strongly associated with either geographic regions or edaphic forest types. Location: Amazonia. Taxon: Angiosperms (Magnoliids; Monocots; Eudicots). Methods: Data for the abundance of 5082 tree species in 1989 plots were combined with a mega-phylogeny. We applied evolutionary ordination to assess how phylogenetic composition varies across Amazonia. We used variation partitioning and Moran\u27s eigenvector maps (MEM) to test and quantify the separate and joint contributions of spatial and environmental variables to explain the phylogenetic composition of plots. We tested the indicator value of lineages for geographic regions and edaphic forest types and mapped associations onto the phylogeny. Results: In the terra firme and várzea forest types, the phylogenetic composition varies by geographic region, but the igapó and white-sand forest types retain a unique evolutionary signature regardless of region. Overall, we find that soil chemistry, climate and topography explain 24% of the variation in phylogenetic composition, with 79% of that variation being spatially structured (R$^{2}$ = 19% overall for combined spatial/environmental effects). The phylogenetic composition also shows substantial spatial patterns not related to the environmental variables we quantified (R$^{2}$ = 28%). A greater number of lineages were significant indicators of geographic regions than forest types. Main Conclusion: Numerous tree lineages, including some ancient ones (>66 Ma), show strong associations with geographic regions and edaphic forest types of Amazonia. This shows that specialization in specific edaphic environments has played a long-standing role in the evolutionary assembly of Amazonian forests. Furthermore, many lineages, even those that have dispersed across Amazonia, dominate within a specific region, likely because of phylogenetically conserved niches for environmental conditions that are prevalent within regions

Geography and ecology shape the phylogenetic composition of Amazonian tree communities

AimAmazonia hosts more tree species from numerous evolutionary lineages, both young and ancient, than any other biogeographic region. Previous studies have shown that tree lineages colonized multiple edaphic environments and dispersed widely across Amazonia, leading to a hypothesis, which we test, that lineages should not be strongly associated with either geographic regions or edaphic forest types.LocationAmazonia.TaxonAngiosperms (Magnoliids; Monocots; Eudicots).MethodsData for the abundance of 5082 tree species in 1989 plots were combined with a mega-phylogeny. We applied evolutionary ordination to assess how phylogenetic composition varies across Amazonia. We used variation partitioning and Moran's eigenvector maps (MEM) to test and quantify the separate and joint contributions of spatial and environmental variables to explain the phylogenetic composition of plots. We tested the indicator value of lineages for geographic regions and edaphic forest types and mapped associations onto the phylogeny.ResultsIn the terra firme and várzea forest types, the phylogenetic composition varies by geographic region, but the igapó and white-sand forest types retain a unique evolutionary signature regardless of region. Overall, we find that soil chemistry, climate and topography explain 24% of the variation in phylogenetic composition, with 79% of that variation being spatially structured (R2 = 19% overall for combined spatial/environmental effects). The phylogenetic composition also shows substantial spatial patterns not related to the environmental variables we quantified (R2 = 28%). A greater number of lineages were significant indicators of geographic regions than forest types.Main ConclusionNumerous tree lineages, including some ancient ones (>66 Ma), show strong associations with geographic regions and edaphic forest types of Amazonia. This shows that specialization in specific edaphic environments has played a long-standing role in the evolutionary assembly of Amazonian forests. Furthermore, many lineages, even those that have dispersed across Amazonia, dominate within a specific region, likely because of phylogenetically conserved niches for environmental conditions that are prevalent within regions