Proceedings. XV Brazilian Symposium on Computer Graphics and Image Processing

This work aims at the implementation of Brazilian vehicle plate localization using image processing techniques. In this paper, we show how to find the horizontal position of the plate based on its frequency characteristics in the whole vehicle image. Preliminary results show efficiencies above 96% for images in good illumination conditions. View full abstract»

We present a model for geometric modeling and rendering of individual feathers for computer graphics purposes. The model represents feather structure with a collection of parameterized Bezier curves. This parametrization allows easy generation of the existent types of feather structures with biologically-motivated parameters. Once the feather structure is defined, feathers can be rendered either i... View full abstract»

This paper presents a new algorithm for recognition of objects in a given image. This algorithm transforms the input image into a directed graph which is constructed through several defined rules. The graph characteristics represent the global shape information of the object inside the input image, and are extracted during graph construction. This strategy prevents the postprocessing traversing to... View full abstract»

We present an experimental setup to evaluate the relative performance of single Gaussian models and Gaussian mixture models for skin color modeling. Firstly, a sample set of 1,120,000 skin pixels from a number of ethnic groups is selected and represented in the chromaticity space. Parameter estimation for both the single Gaussian and seven (with 2 to 8 Gaussian components) Gaussian mixture models ... View full abstract»

The watershed transform has been used for image segmentation relying mostly on image gradients. However, background noise tends to produce spurious gradients, that cause over-segmentation and degrade the output of the watershed transform. Also, low-contrast edges produce gradients with small magnitudes, which may cause different regions to be erroneously merged. In this paper, a new technique is p... View full abstract»

This article reports on the application of the recently introduced concept of multiscale fractal dimension (MFD) as a resource for quantifying three-dimensional gene expression patterns in embryonic development. While traditional fractal dimensions provide interesting possibilities for quantifying pattern complexity, as defined by the intensity in which the pattern interacts with its surrounding s... View full abstract»

This paper presents a model describing intelligent information present in the virtual environment, as well as camera control. We are interested in modeling intelligent virtual environments, integrated with intelligent camera control in order to provide information to be used in behavioural simulations. Our main goal is to be able to populate virtual environments with virtual agents endowed with di... View full abstract»

An improved Zernike moment using as a region-based shape descriptor is presented. The improved Zernike moment not only has rotation invariance, but also has scale invariance that the unimproved Zernike moment does not have. The experimental results show that the improved Zernike moment has better invariant properties than unimproved Zernike moment using as region-based shape descriptor. View full abstract»

The boundary identification represents an interesting and difficult problem in image processing, mainly if two flat zones are separated by a gradual transition. The most common operators work very well for sharp edges, but fail for gradual transitions. In this work, we have done a characterization for gradient by a study of the opening residues. This characterization is useful to identify and clas... View full abstract»

Interaction between human and computer has been used in a large scale in computer graphics and virtual reality. This paper presents a system to provide interaction between user and virtual humans. The system uses a data glove and an artificial neural network system responsible for the recognition of hand postures. View full abstract»

This paper presents a new hierarchical facial model that conforms to the human anatomy for realistic and fast 3D facial expression synthesis. The facial model has a skin/muscle/skull structure. The deformable skin model uses a kind of nonlinear spring to directly simulate the nonlinear visco-elastic behavior of soft tissue, and a new kind of edge repulsion spring is developed to prevent model coll... View full abstract»

We present a hybrid system using computer vision and graphics methods that effectively combines fast automatic 3D model extraction with view-dependent texture mapping for the purpose of real-time person-to-person 3D video teleconferencing. In our approach the problem of creating a dense disparity map is bypassed. We compute only a sparse geometric model, which is textured from multiple cameras usi... View full abstract»

New advances in image based texture synthesis techniques allow the generation of arbitrarily sized textures based on a small sample. The generated textures are perceived as very similar to the given sample. One main drawback of these techniques, however, is that the synthesized result cannot be locally controlled, that is, we are able to synthesize a larger version of the sample but without much v... View full abstract»

This paper presents the generation of realistic morphologically neural cells employing a modified L-System. These grammars incorporate functions that refer to the morphological features extracted from natural cells (e.g. branch dendritic, angle and size). A parser is used to generate the neural cells, which can be viewed by a 3D visualization software specifically developed to show the branching s... View full abstract»

In a collaborative modelling environment, multiple users may interact in a virtual environment to deform or modify shared 3D objects (e.g., for modelling and visualization of virtual prototypes). The challenges to collaborative modelling are related mainly to four aspects: user interaction with the virtual modelling environment, 3D object concurrent editing, consistency maintenance among client te... View full abstract»

This paper tackles the problem of estimating the parameters of relevant distributions that describe speckled imagery. Speckle noise appears in data obtained with coherent illumination, as is the case of sonar, laser, ultrasound-B and synthetic aperture radar images. This noise is non-Gaussian and non-additive and, therefore, classical techniques of processing and analysis may fail. A universal par... View full abstract»

We show how to use affine arithmetic to represent a parametric curve with a strip tree. The required bounding rectangles for pieces of the curve are computed by exploiting the linear correlation information given by affine arithmetic. As an application, we show how to compute approximate distance fields for parametric curves. View full abstract»

We address the problem of filtering three-dimensional sparse data representing real objects. The main application is to eliminate points that are not structured on surfaces. Points classified as organized can be the input for other processes. An accumulation process infers the organization of each input element. The tensorial fields used in our method act as three-dimensional structuring elements.... View full abstract»

We present a new method for painterly rendering of images. Our method extends the image-moment stroke placement algorithm in two ways: we employ a multiscale scheme for computing strokes and we provide a parametrized mechanism for controlling stroke distribution. In addition, we present a specialized image abstraction for the algorithm. View full abstract»

Digital change detection methods have been broadly divided into either pre-classification spectral change detection or post-classification change detection. Since all spectral change detection methods are based on pixel-wise operations, or scene-wise plus pixel-wise operations, accuracy in image registration and scene-to-scene radiometric normalization is more critical for these methods than for o... View full abstract»

This work presents a method to output the 3D structure of an urban area from only one aerial photo. The reconstruction is based on the inverse process done when a parallel projection is used to construct a two-dimensional image from a three-dimensional object. A new algorithm for reconstruction is developed and implemented. It recovers depth information by identification of object height on the im... View full abstract»

The visualization of medical images, e.g. Computed Tomography (CT) and Magnetic Resonance Imaging (MRI), and the utilization of measurement tools to define distances, areas and volumes are very important to health professionals. The quantitative analysis of spatial relations among structures is useful for medical diagnosis. This work describes a visualization system that provides interactive measu... View full abstract»

We discuss the importance of using different elements to accomplish a better learning of computer graphics related concepts, and how to make this information available in a way accessible for students that is useful as learning support tools. We propose and assess the use of a resource site in order to increase the interaction between the courses in the area. View full abstract»