{"title":"Cache management for real time visualization of 2D data sets","authors":"A. Matos, João Pedro Gomes, Luiz Velho","doi":"10.1109/SIBGRA.1998.722740","DOIUrl":"https://doi.org/10.1109/SIBGRA.1998.722740","url":null,"abstract":"We present a general cache management algorithm with data pre-loading that optimizes access to data in real-time applications. We show that our algorithm provides the optimum results when the visualization sequence is known. We also present an oracle that estimates the visualization sequence for 2D data sets, and show the results of the algorithm in a virtual panorama viewer.","PeriodicalId":282177,"journal":{"name":"Proceedings SIBGRAPI'98. International Symposium on Computer Graphics, Image Processing, and Vision (Cat. No.98EX237)","volume":"28 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":"133976922","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":"Image-based modeling using a two-step camera calibration method","authors":"P. Carvalho, F. Szenberg, M. Gattass","doi":"10.1109/SIBGRA.1998.722777","DOIUrl":"https://doi.org/10.1109/SIBGRA.1998.722777","url":null,"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, synthetic information can be superimposed onto the image and arbitrary views can be produced. Using this methodology, we developed virtual referee, an application to analyze soccer plays from still images, generating an OpenGL camera over a 3D field model.","PeriodicalId":282177,"journal":{"name":"Proceedings SIBGRAPI'98. International Symposium on Computer Graphics, Image Processing, and Vision (Cat. No.98EX237)","volume":"31 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":"130017854","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":"An algorithm for intersecting and trimming parametric meshes","authors":"L. Coelho, M. Gattass, L. de Figueiredo","doi":"10.1109/SIBGRA.1998.722737","DOIUrl":"https://doi.org/10.1109/SIBGRA.1998.722737","url":null,"abstract":"We present an algorithm for intersecting finite-element meshes defined on parametric surface patches. The intersection curves are modeled precisely and both meshes are adjusted to the newly formed borders. The algorithm is part of an interactive shell modeling program, which has been used in the design of large offshore oil structures. We avoid unacceptable interaction delays by using a variant of the DCEL data structure that stores topological entities in spatial indexing trees instead of linked lists. These trees speed up the intersection computations required to determine points of the trimming curves, and also allows mesh reconstruction using only local queries.","PeriodicalId":282177,"journal":{"name":"Proceedings SIBGRAPI'98. International Symposium on Computer Graphics, Image Processing, and Vision (Cat. No.98EX237)","volume":"52 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":"115373575","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":"Evaluation of three-dimensional reconstructions from arbitrary images","authors":"R. Mendonca, M. Campos","doi":"10.1109/SIBGRA.1998.722779","DOIUrl":"https://doi.org/10.1109/SIBGRA.1998.722779","url":null,"abstract":"This paper investigates computer vision techniques for three-dimensional reconstruction having as source of information non-professional images captured from cameras of arbitrary position and orientation. The main purpose is to compose a methodology for 3D reconstruction, aiming specially at its use in the documentation of historic buildings and monuments through their three-dimensional modeling. For being particularly suitable, the technique of shape from stereo is then more closely analysed. Laboratory experiments, with controlled environment and objects are carried out in order to study the influence of some elements in the quality of reconstruction. A practical application with actual photographs of old buildings is presented, and final conclusions are drawn.","PeriodicalId":282177,"journal":{"name":"Proceedings SIBGRAPI'98. International Symposium on Computer Graphics, Image Processing, and Vision (Cat. No.98EX237)","volume":"72 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":"122614374","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":"Binary filter estimation for large windows","authors":"E. Dougherty","doi":"10.1109/SIBGRA.1998.722728","DOIUrl":"https://doi.org/10.1109/SIBGRA.1998.722728","url":null,"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 constrained filter requiring less parameters. This paper examines the relationship between estimation precision and constraint. It focuses on binary filters, relevant Chebyshev bounds, and the relationships between the kernels of optimal, constrained, and estimated filters. It describes constraint via iterative design and secondarily constrained filters, as well as using suboptimal filters as prior filters for the estimation of optimal filters using new data.","PeriodicalId":282177,"journal":{"name":"Proceedings SIBGRAPI'98. International Symposium on Computer Graphics, Image Processing, and Vision (Cat. No.98EX237)","volume":"34 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":"123188628","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":"Computer vision-based navigation for autonomous blimps","authors":"L.S. de Coelho, M. Campos, V. Kumar","doi":"10.1109/SIBGRA.1998.722762","DOIUrl":"https://doi.org/10.1109/SIBGRA.1998.722762","url":null,"abstract":"Autonomous dirigibles-aerial robots that are a blimp controlled by computer based on information gathered by sensors-are a new and promising research field in robotics, offering several original work opportunities. One of them is the study of visual navigation, that would allow an autonomous dirigible to follow precise trajectories based on environmental visual information imaged by on-board cameras. The first step in the direction of the developing of such a capacity is the creation of a computer vision system able to supply to the autonomous dirigible its position and orientation in tridimensional space from the acquired images. This project describes such a system, capable of estimating position and orientation from images of visual beacons-objects with known geometrical properties and recognizable by the system. Experimental results showing the correct and efficient functioning of the system are shown and implications and future possibilities are discussed.","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":"128814546","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":"Three-dimensional reconstruction and visualization of tomographic images system using frequential techniques and wavelets","authors":"E. R. Minatel, P. E. Cruvinel","doi":"10.1109/SIBGRA.1998.722731","DOIUrl":"https://doi.org/10.1109/SIBGRA.1998.722731","url":null,"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 /spl gamma/-ray computerized minitomograph scanners for soil science developed at the Brazilian Enterprise for Agricultural Research (EMBRAPA Agricultural Instrumentation). Also for two-dimensional images some advantages were observed when compared with the filtered backprojection method for a particular set of phantom images. The system was developed in Pascal and C/C++ languages under a Windows environment.","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":"116661572","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":"On the efficacy of texture analysis for crowd monitoring","authors":"A. Marana, L. F. Costa, R. Lotufo, S. Velastín","doi":"10.1109/SIBGRA.1998.722773","DOIUrl":"https://doi.org/10.1109/SIBGRA.1998.722773","url":null,"abstract":"The goal of this work is to assess the efficacy of texture measures for estimating levels of crowd densities in images. This estimation is crucial for the problem of crowd monitoring and control. The assessment is carried out on a set of nearly 300 real images captured from Liverpool Street Train Station, London, UK, using texture measures extracted from the images through the following four different methods: gray level dependence matrices, straight line segments, Fourier analysis, and fractal dimensions. The estimations of crowd densities are given in terms of the classification of the input images in five classes of densities (very low, low, moderate, high and very high). Three types of classifiers are used: neural (implemented according to the Kohonen model), Bayesian, and an approach based on fitting functions. The results obtained by these three classifiers, using the four texture measures, allowed the conclusion that, for the problem of crowd density estimation, texture analysis is very effective.","PeriodicalId":282177,"journal":{"name":"Proceedings SIBGRAPI'98. International Symposium on Computer Graphics, Image Processing, and Vision (Cat. No.98EX237)","volume":"17 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":"121877711","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}