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Deaf people use systems of communication based on sign language and finger spelling. Finger spelling is a system where each letter of the alphabet is represented by a unique and discrete movement of the hand. RGB and depth images can be used to characterize hand shapes corresponding to letters of the alphabet. There exists an advantage of depth sensors, as Kinect, over color cameras for finger spelling...
Agents path planning is an essential part of games and crowd simulations. In those contexts they are usually restricted to planar surfaces due to the huge computational cost of mapping arbitrary surfaces to a plane without distortions. Mapping is required to benefit from the lower computational cost of distance calculations on a plane (Euclidean distance) when compared to distances on arbitrary surfaces...
We present an adaptive integration strategy to evaluate the volume rendering integral for regular volumes. We discuss different strategies to control the step size for both the inner and the outer integrals in the volume rendering equation. We report a set of computational experiments that compare both accuracy and efficiency of our proposal against Riemann summation with uniform step size. The comparisons...
The improvement of digital cameras and computers' processing capabilities have made applicable the solutions of a wide range of problems regarding image processing and computer vision. Among the most interesting tasks in this field of expertise, there are several face related problems. Many works have been proposed to solve problems such as face recognition, expression and age estimation, facial reconstruction,...
The difficulty to understand the complex behavior of vector fields makes its visual segmentation an area of constant interest in scientific visualization. In this paper, we present a novel interactive segmentation framework for discrete vector fields. In our method, the vector field domain is partitioned into multiple regions with same flow patterns. In order to accomplish this task, feature vectors...
In this paper, we present an approach to streaming graph-based hierarchical video segmentation by simple label propagation. Here, we transform the streaming video segmentation into a graph partitioning problem in which each part corresponds to one region of the video, furthermore, we apply a simple method for merging the segmentations of two consecutive blocks to achieve the temporal coherence. The...
We present a method for segmenting 2D microscopy images of freshwater green microalgae. Our approach is based on a specialized level set method, leading to efficient and highly accurate algae segmentation. The level set formulation of our problem allows us to generate an algae's boundary curve as the result of an evolving level curve, based on computed background and algae regions in a given image...
Clustering techniques have been widely used in areas that handle massive amounts of data, such as statistics, information retrieval, data mining and image analysis. This work presents a novel image clustering method called Partial Least Square Image Clustering (PLSIC), which employs a one against-all Partial Least Squares classifier to find image clusters with low redundancy (each cluster represents...
This work aims to build a comparison basis for analyzing global illumination methods. We have compared six state-of-the-art global illumination methods, ranging from Monte Carlo Path Tracing techniques to Density Estimation methods such as Progressive Photon Mapping, and the mixture approach Vertex Connection and Merging, using nine test scenes with very different characteristics, including many different...
Due to the subjective nature of the segmentation process, quantitative evaluation of image segmentation methods is still a difficult task. Humans perceive image objects in different ways. Consequently, human segmentations may come in different levels of refinement, ie, under- and over-segmentations. Popular segmentation error measures in the literature (Arbelaez and OCE) are supervised methods (also...
This paper presents a half toning-based watermarking method. This method enables the embedding of a color image into a binary black-and-white halftone, while maintaining the image quality. The proposed technique is capable of embedding watermarks of three color channels into a binary halftone. To achieve high quality halftones, the method maps colors to halftone channels with homogeneous dot patterns...
Multi-frame super-resolution is possible when there is motion and non-redundant information from a sequence of low-resolution input images. Remote sensors, surveillance videos and modern mobile phones are examples of devices able to easily gather multiple images of a same scene. However, combining a large number of frames into a higher resolution image may not be computationally feasible by complex...
Emergency events involving fire are potentially harmful, demanding a fast and precise decision making. The use of crowd sourcing image and videos on crisis management systems can aid in these situations by providing more information than verbal/textual descriptions. Due to the usual high volume of data, automatic solutions need to discard non-relevant content without losing relevant information. There...
Detection of rolling and adhered leukocytes in intravital microscopy image sequences is an important task in studies of leukocyte-endothelial interactions in the microcirculation of living small animals under different inflammatory conditions. This procedure is usually performed by visual assessment of the image sequences. However, despite being tedious and time consuming, this procedure is prone...
We present an efficient technique for modeling and rendering complex surface details defined at multiple scales. Conceptually, meta-relief texture mapping can be described as recursively mapping finer relief-texture layers on top of coarser ones. Such a factorization has several desirable properties. For instance, it provides a way of simulating highly-complex surface details as a combination of simpler...
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