Stefano Foresti

Visual correlation for situational awareness

We present a novel visual correlation paradigm for situational awareness (SA) and suggest its usage in a diverse set of applications that require a high level of SA. Our approach is based on a concise and scalable representation, which leads to a flexible visualization tool that is both clear and intuitive to use. Situational awareness is the continuous extraction of environmental information, its integration with previous knowledge to form a coherent mental picture, and the use of that picture in anticipating future events. In this paper we build on our previous work on visualization for network intrusion detection and show how that approach can be generalized to encompass a much broader class of SA systems. We first propose a generalization that is based on what we term, the w/sup 3/ premise, namely that each event must have at least the what, when and where attributes. We also present a second generalization, which increases flexibility and facilitates complex visual correlations. Finally, we demonstrate the generality of our approaches by applying our visualization paradigm in a collection of diverse SA areas.

Effects of Integrated Graphical Displays on Situation Awareness in Anaesthesiology

Abstract: Anaesthetic information displays have been shown to influence anaesthesiologists’ situation awareness. In study 1 an object display was compared with the traditional display currently used. Twelve anaesthesiologists (residents and faculty members) participated in a simulator evaluation of the displays. Reaction times for detection of critical events and situation awareness were measured. The object display improved situation awareness for one of four test scenarios. Low-level situation awareness was higher with the traditional display, and medium-level situation awareness was higher with the new display. In study 2, an integrated 3D display was compared to the traditional display. Twelve students participated in the evaluation. The new 3D display helped the observers to see changes more rapidly. In one scenario, situation awareness was higher with the new display than with the traditional display. In summary, during 63% of the simulated scenarios, reliable differences were found in favour of the new displays. Thus, by introducing integrated graphical displays in the operating room, anaesthesiologists’ performance may be improved.

Eigen analysis of cone-beam scanning geometries

Eigen analysis is able to diagnose invertibility and noise sensitivity of systems of linear equations. An eigen analysis is applied to a realistic size cone-beam reconstruction problem in SPECT to evaluate various scanning orbit trajectories. Attenuation and truncation problems are considered. For each orbit, the cone-beam reconstruction problem is modeled as a system of 65 × 65 × 128 = 540800 linear equations. Due to the large system of linear equations, the Lanczos iterative method is used to estimate the condition number. A circular sine-wave trajectory is determined to be the most stable sampling scheme of the orbits investigated.

Efficient estimation of dynamic cardiac SPECT kinetic parameters using weighted least squares estimates of dynamic reconstructions

Efficient estimates of dynamic cardiac SPECT kinetic parameters are determined using weighted least squares fitting that incorporates the variance and covariance of weighted least squares estimates of dynamic reconstructions. Sequential tomographic projections are reconstructed into a sequence of 64/spl times/64 transaxial images for one transaxial slice using for each reconstruction in the time sequence a separate singular value decomposition to calculate the weighted reconstruction estimate. Attenuation factors are included in the projection equations and are calculated from a transmission reconstruction. Time-activity-curves for a sum of activity in a blood region inside the left ventricle and a sum in a cardiac tissue region, for the variance of the two estimates of the sum, and for the covariance between the two ROI estimates are generated from the attenuation corrected transaxial reconstructions. A two-compartment model is fit to the blood and tissue activity curves to give weighted least squares estimates of blood volume fraction, wash-in and wash-out rate constants specifying teboroxime kinetics for the left ventricular myocardium. For the data obtained in a dynamic cardiac SPECT study, weighted least squares reconstructions do not necessarily give more efficient estimates of the tissue kinetic parameters.

Parallel rapid operator for iterative finite element solvers on a shared memory machine

Abstract The p -version of the finite element method, which uses high order hierarchic basis functions within an element, allows for ease of adaptive computation, and high accuracy with relatively few degrees of freedom. However, the solution time and storage requirements for large three-dimensional problems can be very high when a global matrix is assembled. The use of rapid operator application in iterative methods leads to minimal storage requirements, because neither elemental nor global matrices are formed. We show in this paper that this algorithm is amenable to parallel and vector computation, and is readily implemented on shared memory machines. Elements are assigned to processors as they become available, and the computations are completely dominated by matrix-matrix multiplications, which can be tuned for maximum speed. Results showing the high efficiency and scalability of such a scheme on an IBM 3090/600 with Vector Facility are given.

VisAlert: From Idea to Product

Visalert is a visualization system designed to increase the monitoring and correlation capabilities of computer network analysts engaged in intrusion detection and prevention. VisAlert facilitates and promotes situational awareness in complex network environments by providing the user with a holistic view of network security to aid in the detection of sophisticated and malicious activities, and ability to zoom in-out information of interest. The system provides a mechanism to access data from multiple databases, and to correlate who, what, when and where. This chapter describes the design process that enabled the team to go from the conception of rough visual sketches to the implementation and deployment of a finished software. In addition, the chapter describes the issues that the interdisciplinary team had to address to carry the project from idea to product.

Between Art, Science and Technology: Data Representation Architecture

As our civilization continues to dive deeper into the information age, making sense of complex data becomes critical. This work takes on this challenge by means of a novel method based on complete inter disciplinarity, design process and built-in evaluations. The result is the design, construction, testing and deployment of data environments supporting real-time decision-making in such diverse domains as anesthesiology and live art performance. Fundraising success, technology licensing, market implementation and many live art performances provide evidence of the great potential of committed interdisciplinary work for advancing science, art and technology while benefiting society at large.

Visualizing the unseen body. Architectural potentials of data modeling

The project is a digital architectural visualization of an individuals physiological data in real time. It is both a probing and representational system that brings together science and art through architectural design. Architecture provides the conceptual and visual tools for expressing the complexities of an individuals physiological state. Visualizing the intricate nature of organic life awakens the unfolding nature of our being.

Architectural Research in Information Visualization: 10 Years after

As our civilization dives deeper into the information age, making sense of ever more complex and larger amounts of data becomes critical. This article reports on interdisciplinary work in Information Visualization addressing this challenge and using architectural expertise as its main engine. The goal of this research is to significantly improve real time decision making in complex data spaces while devising a new architecture that responds to complex information environments. Although we have been reporting in aspects of this work for the past 7 years, this paper covers unpublished knowledge, design methods, operational strategies, and other details that bring together all the material published by our group thus far into a comprehensive and useful whole. We conclude by presenting our latest InfoVis design work in Network Security.

Parallel Least Squares Estimates of 2-D SPECT Image Reconstructions on the SGI Power Challenge

Single photon emission computed tomography (SPECT) has become an important diagnostic tool in nuclear medicine, because of the important clinical role that it can offer. Reconstruction methods, necessary to compensate several effects that severely degrade the quality of the image, are computationally very intensive.