{"title":"Noise in bilinear problems","authors":"J. Haddon, D. Forsyth","doi":"10.1109/ICCV.2001.937684","DOIUrl":"https://doi.org/10.1109/ICCV.2001.937684","url":null,"abstract":"Despite the wide application of bilinear problems to problems both in computer vision and in other fields, their behaviour under the effects of noise is still poorly understood. In this paper, we show analytically that marginal distributions on the solution components of a bilinear problem can be bimodal, even with Gaussian measurement error. We demonstrate and compare three different methods of estimating the covariance of a solution. We show that the Hessian at the mode substantially underestimates covariance. Many problems in computer vision can be posed as bilinear problems: i.e. one must find a solution to a set of equations of the form.","PeriodicalId":429441,"journal":{"name":"Proceedings Eighth IEEE International Conference on Computer Vision. ICCV 2001","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129625270","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":"Multi-agent event recognition","authors":"Somboon Hongeng, R. Nevatia","doi":"10.1109/ICCV.2001.937608","DOIUrl":"https://doi.org/10.1109/ICCV.2001.937608","url":null,"abstract":"This paper presents a new approach to recognizing multiagent events observed by a static camera. To track objects robustly, knowledge about the ground plane and the events is used. An event is considered as composed of action threads, each thread being executed by a single actor. A single thread of action is recognized from the characteristics of the trajectory and moving blob of the actor using Bayesian methods. A multi-agent event is represented by a number of action threads related by temporal constraints. Multi-agent events are recognized by propagating the constraints and likelihoods of event threads in a temporal logic network.","PeriodicalId":429441,"journal":{"name":"Proceedings Eighth IEEE International Conference on Computer Vision. ICCV 2001","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129183105","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":"Accurate catadioptric calibration for real-time pose estimation in room-size environments","authors":"Daniel G. Aliaga","doi":"10.1109/ICCV.2001.937508","DOIUrl":"https://doi.org/10.1109/ICCV.2001.937508","url":null,"abstract":"Omnidirectional video cameras are becoming increasingly popular in computer vision. One family of these cameras uses a catadioptric system with a paraboloidal mirror and an orthographic lens to produce an omnidirectional image with a single center-of-projection. In this paper, we develop a novel calibration model that we combine with a beacon-based pose estimation algorithm. Our approach relaxes the assumption of an ideal paraboloidal catadioptric system and achieves an order of magnitude improvement in pose estimation accuracy compared to calibration with an ideal camera model. Our complete standalone system, placed on a radio-controlled motorized cart, moves in a room-size environment, capturing high-resolution frames to disk and recovering camera pose with an average error of 0.56% in a region 15 feet in diameter.","PeriodicalId":429441,"journal":{"name":"Proceedings Eighth IEEE International Conference on Computer Vision. ICCV 2001","volume":"59 20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121417958","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}
N. Paragios, O. Mellina-Gottardo, Visvanathan Ramesh
{"title":"Gradient vector flow fast geodesic active contours","authors":"N. Paragios, O. Mellina-Gottardo, Visvanathan Ramesh","doi":"10.1109/ICCV.2001.937500","DOIUrl":"https://doi.org/10.1109/ICCV.2001.937500","url":null,"abstract":"This paper proposes a new front propagation flow for boundary extraction. The proposed framework is inspired by the geodesic active contour model and leads to a paradigm that is relatively free from the initial curve position. Towards this end, it makes use of a recently introduced external boundary force, the gradient vector field that refers to a spatial diffusion of the boundary information. According to the proposed flow, the traditional boundary attraction term is replaced with a new force that guides the propagation to the object boundaries from both sides. This new geometric flow is implemented using a level set approach, thereby allowing dealing naturally with topological changes and important shape deformations. Moreover the level set motion equations are implemented using a recently introduced numerical approximation scheme, the Additive Operator Splitting Schema (AOS) which has a fast convergence rate and stable behavior. Encouraging experimental results are provided using real images.","PeriodicalId":429441,"journal":{"name":"Proceedings Eighth IEEE International Conference on Computer Vision. ICCV 2001","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114624937","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":"Physics-based model acquisition and identification in airborne spectral images","authors":"D. Slater, G. Healey","doi":"10.1109/ICCV.2001.937633","DOIUrl":"https://doi.org/10.1109/ICCV.2001.937633","url":null,"abstract":"We consider the problem of acquiring models for unknown materials in airborne 0.4 /spl mu/m-2.5 /spl mu/m hyperspectral imagery and using these models to identify the unknown materials an image data obtained under significantly different conditions. The material models are generated using an airborne sensor spectrum measured under unknown conditions and a physical model for spectral variability. For computational efficiency, the material models are represented using low-dimensional spectral subspaces. We demonstrate the effectiveness of the material models using a set of material tracking experiments in HYDICE images acquired in a forest environment over widely varying conditions. We show that techniques based on the new representation significantly outperform methods based on direct spectral matching.","PeriodicalId":429441,"journal":{"name":"Proceedings Eighth IEEE International Conference on Computer Vision. ICCV 2001","volume":"108 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131990582","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":"Occlusion robust adaptive template tracking","authors":"H. Nguyen, M. Worring, R. V. D. Boomgaard","doi":"10.1109/ICCV.2001.937587","DOIUrl":"https://doi.org/10.1109/ICCV.2001.937587","url":null,"abstract":"We propose a new method for tracking rigid objects in image sequences using template matching. A Kalman filter is used to make the template adapt to changes in object orientation or illumination. This approach is novel since the Kalman filter has been used in tracking mainly for smoothing the object trajectory. The performance of the Kalman filter is further improved by employing a robust and adaptive filtering algorithm. Special attention is paid to occlusion handling.","PeriodicalId":429441,"journal":{"name":"Proceedings Eighth IEEE International Conference on Computer Vision. ICCV 2001","volume":"189 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131493404","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 data-driven model for monocular face tracking","authors":"Salih Burak Göktürk, J. Bouguet, R. Grzeszczuk","doi":"10.1109/ICCV.2001.937695","DOIUrl":"https://doi.org/10.1109/ICCV.2001.937695","url":null,"abstract":"This paper describes a two-stage system for 3D tracking of pose and deformation of the human face in monocular image sequences without the use of special markers. The first stage of the system learns the space of all possible facial deformations by applying principal component analysis on real stereo tracking data. The resulting model approximates any generic shape as a linear combination of shape basis vectors. The second stage of the system uses this low-complexity deformable model for simultaneous tracking of pose and deformation of the face from a single image sequence. This stage is known as model-based monocular tracking. There are three main contributions of this paper. First we demonstrate that a data-driven approach for model construction is suitable for tracking non rigid objects and offers an elegant and practical alternative to the task of manual construction of models using 3D scanners or CAD modelers. Second, we show that such a method exhibits good tracking accuracy (errors less than 5 mm) and robustness characteristics. Third, we demonstrate that our system exhibits very promising generalization properties in enabling tracking of multiple persons with the same 3D model.","PeriodicalId":429441,"journal":{"name":"Proceedings Eighth IEEE International Conference on Computer Vision. ICCV 2001","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131809839","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":"Indexing based on scale invariant interest points","authors":"K. Mikolajczyk, C. Schmid","doi":"10.1109/ICCV.2001.937561","DOIUrl":"https://doi.org/10.1109/ICCV.2001.937561","url":null,"abstract":"This paper presents a new method for detecting scale invariant interest points. The method is based on two recent results on scale space: (1) Interest points can be adapted to scale and give repeatable results (geometrically stable). (2) Local extrema over scale of normalized derivatives indicate the presence of characteristic local structures. Our method first computes a multi-scale representation for the Harris interest point detector. We then select points at which a local measure (the Laplacian) is maximal over scales. This allows a selection of distinctive points for which the characteristic scale is known. These points are invariant to scale, rotation and translation as well as robust to illumination changes and limited changes of viewpoint. For indexing, the image is characterized by a set of scale invariant points; the scale associated with each point allows the computation of a scale invariant descriptor. Our descriptors are, in addition, invariant to image rotation, of affine illumination changes and robust to small perspective deformations. Experimental results for indexing show an excellent performance up to a scale factor of 4 for a database with more than 5000 images.","PeriodicalId":429441,"journal":{"name":"Proceedings Eighth IEEE International Conference on Computer Vision. ICCV 2001","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133436831","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":"4-sensor camera calibration for image representation invariant to shading, shadows, lighting, and specularities","authors":"G. Finlayson, M. S. Drew","doi":"10.1109/ICCV.2001.937663","DOIUrl":"https://doi.org/10.1109/ICCV.2001.937663","url":null,"abstract":"Most lighting can be accurately modeled using a simplified Planckian function. If we form logarithms of color ratios of camera sensor values, then in a Lambertian plus specular two-lobe model of reflection the temperature-dependent term is separate and is seen as a straight line: i.e., changing lighting amounts to changing each pixel value in a straight line, for a given camera. Here we use a 4-sensor camera. In this case, forming color ratios reduces the dimensionality to 3. Applying logarithms and projecting onto the plane in the 3D color space orthogonal to the light-change direction results in an image representation that is invariant to illumination change. For a given camera, the position of the specular point in the 2D plane is always the same, independent of the lighting. Thus a camera calibration produces illumination invariance at a single pixel. In the plane, matte surfaces reduce to points and specularities are almost straight lines. Extending each pixel value back to the matte position, postulated to be the maximum radius from the fixed specular point, at any angle in the 2D plane, removes specularity. Thus images are independent of shading (by forming ratios), independent of shadows (by making them independent of illumination temperature) and independent of specularities. The method is examined by forming 4D images from hyperspectral images, using real camera sensors, with encouraging results.","PeriodicalId":429441,"journal":{"name":"Proceedings Eighth IEEE International Conference on Computer Vision. ICCV 2001","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131654182","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":"Omni-rig: linear self-recalibration of a rig with varying internal and external parameters","authors":"A. Zomet, Lior Wolf, A. Shashua","doi":"10.1109/ICCV.2001.937509","DOIUrl":"https://doi.org/10.1109/ICCV.2001.937509","url":null,"abstract":"We describe the principles of building a moving vision platform (a Rig) that once calibrated can thereon self-adjust to changes in its internal configuration and maintain an Euclidean representation of the 3D world using only projective measurements. We term this calibration paradigm \"Omni-Rig\". We assume that after calibration the cameras may change critical elements of their configuration, including internal parameters and centers of projection. Theoretically we show that knowing only the rotations between a set of cameras is sufficient for Euclidean calibration even with varying internal parameters and unknown translations. No other information of the world is required.","PeriodicalId":429441,"journal":{"name":"Proceedings Eighth IEEE International Conference on Computer Vision. ICCV 2001","volume":"174 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114439104","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}