Vito Roberto

Efficient stereo with multiple windowing

We present a new, efficient stereo algorithm addressing robust disparity estimation in the presence of occlusions. The algorithm is an adaptive, multi-window scheme using left-right consistency to compute disparity and its associated uncertainty. We demonstrate and discuss performances with both synthetic and real stereo pairs, and show how our results improve on those of closely related techniques for both robustness and efficiency.

Robust motion and correspondence of noisy 3-D point sets with missing data

Abstract We describe RICP, a robust algorithm for registering and finding correspondences in sets of 3-D points with significant percentages of missing data, and therefore useful for both motion analysis and reverse engineering. RICP exploits LMedS robust estimation to withstand the effect of outliers. Our extensive experimental comparison of RICP with ICP shows RICPs superior robustness and reliability.

Making good features track better

This paper addresses robust feature tracking. We extend the well-known Shi-Tomasi-Kanade tracker by introducing an automatic scheme for rejecting spurious features. We employ a simple and efficient outlier rejection rule, called X84, and prove that its theoretical assumptions are satisfied in the feature tracking scenario. Experiments with real and synthetic images confirm that our algorithm makes good features track better; we show a quantitative example of the benefits introduced by the algorithm for the case of fundamental matrix estimation. The complete code of the robust tracker is available via ftp.

Improving Feature Tracking with Robust Statistics

Abstract: This paper addresses robust feature tracking. The aim is to track point features in a sequence of images and to identify unreliable features resulting from occlusions, perspective distortions and strong intensity changes. We extend the well-known Shi–Tomasi–Kanade tracker by introducing an automatic scheme for rejecting spurious features. We employ a simple and efficient outliers rejection rule, called X84, and prove that its theoretical assumptions are satisfied in the feature tracking scenario. Experiments with real and synthetic images confirm that our algorithm consistently discards unreliable features; we show a quantitative example of the benefits introduced by the algorithm for the case of fundamental matrix estimation. The complete code of the robust tracker is available via ftp.

Symmetric stereo with multiple windowing

We present a new, efficient stereo algorithm addressing robust disparity estimation in the presence of occlusions. The algorithm is an adaptive, multiwindow scheme using left–right consistency to compute disparity and its associated uncertainty. We demonstrate and discuss performances with both synthetic and real stereo pairs, and show how our results improve on those of closely related techniques for both accuracy and efficiency.

Model-based planning of optimal sensor placements for inspection

We report a system for sensor planning, GASP, which is used to compute the optimal positions for inspection tasks using known imaging sensors and feature-based object models. GASP (general automatic sensor planning) uses a feature inspection representation (the FIR), which contains the explicit solution for the simplest sensor positioning problem. The FIR is generated off-line, and is exploited by GASP to compute on-line plans for more complex tasks, called inspection scripts. Viewpoint optimality is defined as a function of feature visibility and measurement reliability. Visibility is computed using an approximate model. Reliability of inspection depends on both the physical sensors acquiring the images and on the processing software; therefore we include both these components in a generalized sensor model. These predictions are based on experimental, quantitative assessment. We show how these are computed for a real generalized sensor, which includes a 3-D range imaging system, and software performing robust outlier removal, surface segmentation, object location and surface fitting. Finally, we demonstrate a complete inspection session involving 3-D object positioning, planning optimal position inspection, and feature measurement from the optimal viewpoint.

Internet agents for telemedicine services

Telemedicine can be defined as telematic support of collaboration between distant medical professionals, co-operating on shared resources of various kinds. Attention should be paid to telematics and informatics concepts, especially those oriented towards collaboration. In particular, the recent agent paradigm seems suitable for the analysis, design and development of telemedicine services because of its commitment to intercommunication and sharing of resources. The present paper is an introduction to the agent paradigm from its theoretical basis to the technological issues, and describes an agent-based approach to telemedicine, specifically applied to telepathology applications. The system is based on an agent-based model and template (JAMES) using Java, which has been used to implement a prototype multipurpose telepathology application based on a federated agency architecture.

SSD Disparity Estimation for Dynamic Stereo.

We analyse experimentally some subpixel-accuracy disparity and uncertainty estimators based on the SSD method, frequently used in stereo and motion analysis. We identify key inadequacies, and introduce new, practical algorithms. We discuss results and performance tests, and demonstrate the eeective use of the new estimators in a complete , working system reconstructing dense depth maps using dynamic stereo. The system achieves good accuracy (average percentage errors smaller than few percents) and reliable uncertainty discrimination without any expensive smoothing or regularisation of disparity maps, adopted commonly.

Robust feature tracking in underwater video sequences

The paper proposes a robust feature tracker based on an efficient outlier rejection scheme, suitable for feature tracking in subsea video sequences. We extend the Shi-Tomasi-Kanade scheme (C. Tomasi and T. Kanade, 1991; J. Shi and C. Tomasi, 1994) by introducing a technique for rejecting spurious features. We employ a simple and efficient outlier rejection rule, called X84, and prove that its theoretical assumptions are satisfied in the feature tracking scenario. Experiments with synthetic and real subsea sequence confirm that our algorithm locates and discards unreliable features accurately and consistently, and tracks good features reliably over many frames. We also illustrate quantitatively the benefits introduced by the algorithm with the example of fundamental matrix estimation.

HTML generation and semantic markup for telepathology

Abstract The paper presents a new strategy for the authoring of hypermedia documents; describes an HTML generator called HistMaker, and its application to the domain of Anatomic Pathology. A simple extension to HTML is presented, whose aim is introducing a general-purpose grouping construct to allow the semantic markup of hierarchically structured hypermedia documents. Such a structural information can be used for an effective authoring, browsing and searching of documents. The authoring tool HistMaker is introduced on the basis of a model of a pathologic case; its implementation and practical results are also discussed.