Computer Graphics, Image Processing, and Vision, 1998. Proceedings. SIBGRAPI '98. International Symposium on

The point containment predicate which specifies if a point is part of a mathematically defined shape or not is a crucial problem in computer graphics. This paper presents a stroking technique that counteracts the main disadvantage of point containment algorithms: their quadratic time complexity with increasing resolution. It is also presented an efficient algorithm to perform simultaneously the fi... View full abstract»

This paper describes a technique developed to analyze and recognize paper based electronic circuit diagram images. One of the key aspects of this recognition system relies on the identification of feature points used to guide a new line vectorization method developed for circuit diagram images. The feature paints are also used as a discriminate element in the symbol classification process. Once th... View full abstract»

This paper addresses the problem of automatic synthesis of visual detectors. We present a method using genetic techniques to learn visual features and a program which combines and integrates the features in non-linear ways. The method is integrated in a face tracking system to generate a variety of new visual perceptual processes View full abstract»

The paper presents the foundations of IBAL, a general specification for scene animation. IBAL regulates interactions among graphical elements, such as geometric models and behavioral algorithms, to describe animated scenes. Interactions among graphical elements are managed by primitives which are arranged into three graphs. The three graphs logically partition an animation into “who”, ... View full abstract»

This paper summarizes work done in our laboratory with a special emphasis on functional aspects of the visual field. The quality of the perceived image within a visual display depends on the information available within the display itself but also on the capacity of the human visual system to process visual information. Specifically, the paper discusses work on human visual processing which deals ... View full abstract»

The paper is devoted to the pattern recognition procedure based on the set of expert rules with unprecisely formulated weights understood as conditional probabilities. Adopting the probabilistic model, the recognition algorithm is derived and evaluation of its probability of misclassification is given. Furthermore, the case with both expert rules and the learning set is considered. The proposed al... View full abstract»

Optimal filters are characterized by parameters based on image and filter structure and these parameters need to be estimated from realizations. For fully optimal mean-absolute-error binary filters, conditional expectations need to be estimated. Owing to lack of estimation precision, the resulting estimated filter is likely to be suboptimal. The estimation dilemma can be mitigated by using a const... View full abstract»

This paper presents a system for three-dimensional image reconstruction based on the combination of both adaptive and wavelet reconstruction methods and the use of B-wavelets function for interpolation. Results show the usefulness of the system for three-dimensional image reconstruction and also after interpolation with data obtained by X and γ-ray computerized minitomograph scanners for soi... View full abstract»

This paper describes a method to correct lens distortion for digital cameras. A simple but effective distortion model using local spatial transformation will be used. In addition, the effect of effective focal length on the distortion model will be considered, and we will discuss how to introduce this factor to enhance the model. Finally we have some theoretical analysis and experiments demonstrat... View full abstract»

We describe an interactive video-on-demand (VoD) service, which supports VCR-like functions. It consists of two parts. The first part is a database, which contains the information concerning the videos. This information is published on an Intranet Web. The second part is the actual video distribution using the client server model. The architecture combines network manipulation of high level and a ... View full abstract»

Due to the concentration of users in certain regions of the virtual world, distributed virtual reality systems-DVRS-may become unbalanced, resulting in low performance and bad utilization of system resources. The authors studied this problem and proposed a queueing model and load balancing algorithms to reduce these effects. Some experiments showed how the utilization and response time of the syst... View full abstract»

Visual information retrieval systems have been developed from the necessity of searching and recovering data in libraries with million of daily produced digital images. In image retrieval based on their color content, the distance between color histograms defines usually the matching degree. Results of an image querying depend, at least, on the following features: the underlying color space, the n... View full abstract»

In this work we study algorithms for obtaining simplified representations of terrain models. Terrain data is difficult to deal with, due to its complexity and size. Simplification methods are some of the techniques used to reduce its natural complexity. Among these methods, greedy insertion with vertical local error measure is considered to be the one that yields best results. In spite of its qual... View full abstract»

The correction of handwritten word skew is an arduous task that must be independent of due to style and writing conditions variations. We propose here a morphology-based method to detect and correct handwritten word skew in the treatment of dates written on bank checks. Our aim is to limit the number of parameters and heuristic features necessary for a good skew correction. Our approach is based o... View full abstract»

This paper presents a nonlinear adaptive filter based on the the maximum a posteriori (MAP) approach to reduce speckle in one-look, linear detected SAR images. The k-means clustering algorithm is combined with the MAP filter in order to cluster pixels with similar statistics (Changle Li's variance ratio). Assigned to each cluster there is a window size which is used to estimate the filter paramete... View full abstract»

Vision is an active process where behaviorally important information is selectively gathered. We present a model of visual recognition in which the high resolution fovea is deployed to interesting regions by selective attention processes. The raw image is initially represented by a space variant complex cell, or oriented edge map. This transformed input is processed by a decision system which atte... View full abstract»

Computer animation is a multifaceted field of computer graphics. This presentation explores one of these facets. At first computer animation is surveyed through the use of a framework to help to order and classify its main approaches related to movement modeling. Then the use of Petri nets as a modeling and simulation tool to obtain some kind of foresight of a developed animation is discussed View full abstract»

In the advent of the ubiquity of distributed computing with multimedia capabilities, it is very natural to contemplate collaborations that were not previously possible. In the past scientists, doctors, educators, engineers always had need to share, exchange, debate their work, designs, methodology, knowledge and experience. This was commonly done by attending meetings, publishing in common journal... View full abstract»

An image compression/decompression method is proposed, based on a new interpolation formula of Hermite-Birkhoff type. It is based on a function representation that uses a truncated multipoint Taylor (MT) series. Given a regularly tabulated image, first spatial derivatives (up to a chosen order) are computed by a FFT algorithm. Secondly a knot placing strategy selects sample point positions. The im... View full abstract»

We present a two-step camera calibration process based on linear least squares formulations. We show how to apply this process to build an integrated modeling environment, in which a scene is modeled by having the user specify, on a given image, a set of reference points (used for camera calibration) and object points (used for positioning the objects in the scene). Once this has been done, synthe... View full abstract»

The problem of matching two images can be posed as finding a displacement field which assigns each point of the reference image to a point in the test image. In this paper we present an iterative algorithm to estimate the probability density function relating the intensity distribution of two MR scanners, based on the topological constraints embedded in the elastic matching model. The set of image... View full abstract»

The paper describes Interface, a real time facial animation system. The system uses a simple set of pre modeled facial expressions to create a wide range of emotions, mouth positions and complete head movements. The animation is done through layered groups of actions that combined gives the virtual actor complete freedom to perform different actions independently and simultaneously, without the in... View full abstract»

Computational visualization systems and techniques have improved information gathering activities and changed the ways in which science is studied. However, the complexity of the data handled by such systems has suggested the need for alternative representation and display techniques. Auditory display has been considered to be a real possibility in this area, in a field known as sonification. The ... View full abstract»