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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...
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...
3D shape design tends to be a long and tedious process, with the design of a detailed 3D part usually requiring multiple revisions. Fabricating physical prototypes using low cost 3D fabrication technologies at intermediate stages of the design process is now a common practice, which helps the designer discover errors, and to incrementally refine the design. Most often, implementing the required changes...
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...
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 presents an image classification method based on bag of features, that needs less local features extracted for create a representative description of the image. The feature vector creation process of our approach is inspired in the cortex-like mechanisms used in "Hierarchical Model and X" proposed by Riesenhuber & Poggio. Bag of Max Features - BMAX works with the distance...
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...
When training morphological operators that are locally defined with respect to a neighborhood window, one must deal with the trade off between window size and statistical precision of the learned operator. More precisely, too small windows result in large restriction errors due to the constrained operator space and, on the other hand, too large windows result in large variance error due to often insufficient...
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...
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...
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...
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