{"title":"Comparing the influence of color spaces and metrics in content-based image retrieval","authors":"E. Mathias, A. Conci","doi":"10.1109/SIBGRA.1998.722775","DOIUrl":"https://doi.org/10.1109/SIBGRA.1998.722775","url":null,"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 number of histogram bins, and the metric used for histogram matching. Several systems have been designed for image retrieval. Comparison among them is not feasible because they use completely different implementation aspects. The purpose of this paper is to evaluate the influence of color spaces and metrics on the performances of recovering by color similarity based on color histograms. A system that performs queries through the Internet and allows one to combine metrics and color spaces is implemented. We design a database with groups of perceptually similar color image, with parameters to measure the performance among combined approaches, and with a user-consult simulator. This leads to a process of establishing the influence of spaces and metrics which evaluate the better combination on retrieval.","PeriodicalId":282177,"journal":{"name":"Proceedings SIBGRAPI'98. International Symposium on Computer Graphics, Image Processing, and Vision (Cat. No.98EX237)","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126722123","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Visualization of geological prospecting data","authors":"K. Basso, C. M. Dal Sasso Freitas","doi":"10.1109/SIBGRA.1998.722744","DOIUrl":"https://doi.org/10.1109/SIBGRA.1998.722744","url":null,"abstract":"Oil reservoirs searching is based on several exploratory methods, which produce a large quantity of data that must be interpreted and analyzed by geologists. Graphic systems can help these tasks by providing three-dimensional representations to convey information in a more natural and efficient way to the users. Therefore, they are typical scientific visualization applications. This paper presents results from work on the development of interactive visualization tools for the analysis of geological data obtained from well samples. Since these data are essentially scattered, interpolation techniques are required to the creation of geological models. The system provides a data base management system for storing information used by both interpolation and visualization modules. The modified Shepard interpolation method was implemented and some improvements were made to generate more accurate results in sparsely sampled regions. The visualization module uses the Visualization Toolkit (VTK) to create images showing geological layers as three-dimensional surfaces with attributes mapped to colors and isocontour maps.","PeriodicalId":282177,"journal":{"name":"Proceedings SIBGRAPI'98. International Symposium on Computer Graphics, Image Processing, and Vision (Cat. No.98EX237)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131445293","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D.C. Fernandez, R. De Peralta Menendez, S. Andino, E.O. Farras
{"title":"Comparison of different source localization methods","authors":"D.C. Fernandez, R. De Peralta Menendez, S. Andino, E.O. Farras","doi":"10.1109/SIBGRA.1998.722767","DOIUrl":"https://doi.org/10.1109/SIBGRA.1998.722767","url":null,"abstract":"The localization of the neural generators of the brain's electromagnetic activity based an electrical or magnetic recordings requires the solution of an ill-posed inverse problem. In its general form, this inverse problem has no unique solution. The only way to deal with this problem, is to restrict the set of possible solutions by using either anatomical or mathematical constraints or a combination of both. On the basis of these restrictions, different reconstructions of the sources of EEG and MEG are possible, each providing a different representation of the electrical processes in the brain. Opposed to the more classical dipole localization methods, inverse procedures that produce distributed estimates of neuronal currents have received increasing attention in the last few years. In this paper, we compare different source localization methods using data from a pathological subject. Among these methods are: (1) spatio-temporal source models (BESA); (2) generalized minimum norm solutions (MNS) and (3) electromagnetic temporal tomography (EMTT). In order to assess their specific performance, each method is compared with the information contained in the CT.","PeriodicalId":282177,"journal":{"name":"Proceedings SIBGRAPI'98. International Symposium on Computer Graphics, Image Processing, and Vision (Cat. No.98EX237)","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132634843","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Antunes Montenegro, M. Gattass, P. Cezar Pinto Carvalho
{"title":"Error measures in greedy insertion simplification methods","authors":"A. Antunes Montenegro, M. Gattass, P. Cezar Pinto Carvalho","doi":"10.1109/SIBGRA.1998.722736","DOIUrl":"https://doi.org/10.1109/SIBGRA.1998.722736","url":null,"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 qualities, the method presents shortcomings, especially when applied to terrain with different height variation regions. We investigate the existence of better error measures to deal with this situation and propose the adoption of greedy insertion methods in which the local vertical error is modified according to the variability of the surface in a neighborhood of the point under consideration. The proposed error measure used with the greedy algorithms yields a significant improvement in the visualization process.","PeriodicalId":282177,"journal":{"name":"Proceedings SIBGRAPI'98. International Symposium on Computer Graphics, Image Processing, and Vision (Cat. No.98EX237)","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133919783","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E.O. Farras, R. De Peralta Menendez, S. G. González Andino, D.C. Fernandez, E. A. Vázquez
{"title":"An approach to physiologically meaningful distributed inverse solutions to the neuro-electromagnetic inverse problem","authors":"E.O. Farras, R. De Peralta Menendez, S. G. González Andino, D.C. Fernandez, E. A. Vázquez","doi":"10.1109/SIBGRA.1998.722768","DOIUrl":"https://doi.org/10.1109/SIBGRA.1998.722768","url":null,"abstract":"The problem of determining the generators of brain electromagnetic activity has no unique solution. The only way to deal this problem, sometimes denominated \"the problem of the non-uniqueness\", is to restrict the set of possible solutions by using either physiological or mathematical constraints or a combination of both. The main purpose of this work is to propose a method for obtaining a unique distributed solution to the neuro-electromagnetic inverse problem by considering physiological constraints regarding the spatio temporal distribution of the generators. We will focus in discussing distributed inverse solutions (given in terms of the current density vector) which are general enough to include the concentrated inverse solution. Aspects related to the uniqueness of the new inverse solution proposed are discussed that suggest that this solution warrants further development. We consider as the main merit of this proposal the possibility of including new terms extracted from the new developments in neurophysiology.","PeriodicalId":282177,"journal":{"name":"Proceedings SIBGRAPI'98. International Symposium on Computer Graphics, Image Processing, and Vision (Cat. No.98EX237)","volume":"74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132213799","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A graph-anisotropic approach to 3-D data segmentation","authors":"R. Chaine, S. Bouakaz, D. Vandorpe","doi":"10.1109/SIBGRA.1998.722759","DOIUrl":"https://doi.org/10.1109/SIBGRA.1998.722759","url":null,"abstract":"In this paper, we present a general framework for the segmentation of surfaces represented by 3-D scattered data. The method we present is based on a contextual anisotropic diffusion scheme. Contextual information at each data point involves the selection of optimal directions, locally representing the shape. Over the set of points, graph based representations are well adapted to gather this kind of information in a single compact description. Thus, we introduce two structures respectively denoted minimal and maximal escarpment trees. Our segmentation process is tightly bound to these structures. It proceeds in two stages. The first stage corresponds to the exploration of the maximal escarpment tree and the detection of atomic regions. Then, the second stage permits the progressive merging of emergent regions over the minimal escarpment tree, subject to implicit conditions on the presence of singularities. The sequence of these two treatments has proven to be effective, it corresponds to a new an original approach of segmentation.","PeriodicalId":282177,"journal":{"name":"Proceedings SIBGRAPI'98. International Symposium on Computer Graphics, Image Processing, and Vision (Cat. No.98EX237)","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123855673","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Accuracy assessment of a photogrammetric close-range reconstruction system","authors":"A. Tommaselli","doi":"10.1109/SIBGRA.1998.722732","DOIUrl":"https://doi.org/10.1109/SIBGRA.1998.722732","url":null,"abstract":"Geometric accuracy of a close-range photogrammetric system is assessed in this paper considering surface reconstruction with structured light as its main purpose. The system is based on an off-the-shelf digital camera and a pattern projector. The mathematical model for reconstruction is based on the parametric equation of the projected straight line combined with collinearity equations. A sequential approach for system calibration was developed and is presented. Results obtained from real data are also presented and discussed. Experiments with real data using a prototype have indicated 0.5 mm of accuracy in height determination and 0.2 mm in the XY plane considering an application where the object was 1630 mm distant from the camera.","PeriodicalId":282177,"journal":{"name":"Proceedings SIBGRAPI'98. International Symposium on Computer Graphics, Image Processing, and Vision (Cat. No.98EX237)","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126134438","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Virtual seismic interpretation","authors":"L. A. Lima, R. Bastos","doi":"10.1109/SIBGRA.1998.722741","DOIUrl":"https://doi.org/10.1109/SIBGRA.1998.722741","url":null,"abstract":"This paper presents an application of the virtual reality paradigm to scientific visualization. We describe how the seismic interpretation task performed in oil and gas companies can be facilitated by using immersion techniques inherent to virtual reality. The feeling of immersion allows an easier and better understanding and manipulation of the three-dimensional data associated with seismic interpretation. Volume rendering is used to provide visual feedback. Acceleration techniques are described to allow the interactivity demanded by virtual environments. Methods for intuitively moving with respect to and interacting with this environment are also presented.","PeriodicalId":282177,"journal":{"name":"Proceedings SIBGRAPI'98. International Symposium on Computer Graphics, Image Processing, and Vision (Cat. No.98EX237)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123558127","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A general specification for scene animation","authors":"G.S. Lee","doi":"10.1109/SIBGRA.1998.722753","DOIUrl":"https://doi.org/10.1109/SIBGRA.1998.722753","url":null,"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\", \"what\", and \"when\". IBAL's unique design permits applications to represent, save, and restore a wide variety of complex scenes. A short summary of existing formats for scene modeling and scene animation is presented to distinguish and to assess the utility of IBAL's design.","PeriodicalId":282177,"journal":{"name":"Proceedings SIBGRAPI'98. International Symposium on Computer Graphics, Image Processing, and Vision (Cat. No.98EX237)","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128372541","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Density estimation for MR image elastic matching","authors":"A. Machado, James C. Gee, Mario F. M. Campos","doi":"10.1109/SIBGRA.1998.722766","DOIUrl":"https://doi.org/10.1109/SIBGRA.1998.722766","url":null,"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 images used as input for the algorithm is the Harvard Atlas. The density estimation resulting from this method is compared with two other algorithms which do not assume any prior information about the media being imaged. The results show that the density estimation obtained with the elastic matching approach produce more realistic deformed images and is suitable to represent MR sensor models.","PeriodicalId":282177,"journal":{"name":"Proceedings SIBGRAPI'98. International Symposium on Computer Graphics, Image Processing, and Vision (Cat. No.98EX237)","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133774112","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}