Due to the surface meshes produced at increasing complexity in many applications, interest in efficient simplification algorithms and multiresolution representation is very high. An enhanced simplification approach together with a general multiresolution data scheme are presented here. JADE, a new simplification solution based on the Mesh Decimation approach has been designed to provide both increased approximation precision, based on global error management, and multiresolution output. Moreover, we show that with a small increase in memory, which is needed to store the multiresolution data representation, we are able to extract any level of detail representation from the simplification results in an extremely efficient way. Results are reported on empirical time complexity, approximation quality, and simplification power. Keywords: surface modeling, mesh simplification, bounded approximation error, multiresolution. Address to which proofs should be sent: R. SCOPIGNO, CNUCE -- Consigl...

The Virtual Assembly Design Environment (VADE) is a Virtual Reality (VR)-based engineering application that allows engineers to evaluate, analyze, and plan the assembly of mechanical systems. This system focuses on utilizing an immersive, virtual environment tightly coupled with commercial computer aided design (CAD) systems. Salient features of VADE include: 1) data integration (two-way) with a parametric CAD system, 2) realistic interaction of user with parts in the virtual environment, 3) creation of valued design information in the virtual environment, 4) reverse data transfer of design information back to the CAD system, 5) significant interactivity in the virtual environment, 6) collision detection, and 7) physically-based modeling. This paper describes the functionality and applications of VADE. A discussion of the limitations of virtual assembly and a comparison with automated assembly planning systems are presented. Experiments conducted using real-world engineering models are also described. 1.

A significant unsolved problem in scientific visualization is how to efficiently visualize extremely large time-varying datasets. Using parallelism provides a promising solution. One drawback of this approach is the high overhead and specialized knowledge often required to create parallel visualization programs. In this paper, we present a parallel visualization system that is scalable, portable and encapsulates parallel programming details for its users. Our approach was to augment an existing visualization system, the visualization toolkit(VTK). Process and communication abstractions were added in order to support task, pipeline and data parallelism. The resulting system allows users to quickly write parallel visualization programs and avoid rewriting these programs when porting to new platforms. The performance of a collection of parallel visualization programs written using this system and run on both a cluster of SGI Origin 2000s and a Linux-based PC cluster is presented. In addit...

This paper describes the 3Book, a 3D interactive visualization of a codex book as a component for digital library and information-intensive applications. The 3Book is able to represent books of almost unlimited length, allows users to read large format books, and has features to enhance reading and sensemaking.

The paper presents a simple and efficient algorithm for the removal of small topological inconsistencies and high frequency details from surface models. The method, called Marching Intersections (MI), adopts a volumetric approach and acts as a resampling filter: all the intersection points between the input model and the lines of a user selected 3D reference grid are located and then, beginning from these intersections, an output surface is reconstructed. MI, which presents good characteristics in terms of efficiency, compactness, and quality of the output models, can be also used: for the conversion between different representation schemes; to perform logical operations on geometric models; for the topological simplification of surfaces; and for the simplification of huge meshes, i.e. meshes too large to be allocated in main memory during the simplification process. All these aspects are discussed in the paper and timing and graphic results are presented.

A research agenda is presented which addresses the current role and potential of map displays. By considering the geospatial data used in visualization, the form and design of maps, the purposes for which map displays are created, the nature of the map user community, and the technology employed to visualize geospatial data, a thorough overview of the nature of cartographic visualization is given. Under the same themes, and sourced in cartographic tradition, cartographic practice and technological opportunities, a series of possible research avenues are highlighted. The important links between representation and the user interface, map user cognition and the geospatial database are stressed.

Abstract—This paper presents a visual-servoing method that is based on 2-D ultrasound (US) images. The main goal is to guide a robot actuating a 2-D US probe in order to reach a desired cross-section image of an object of interest. The method we propose allows the control of both in-plane and out-of-plane probe motions. Its feedback visual features are combinations of moments extracted from the observed image. The exact analytical form of the interaction matrix that relates the image-moments time variation to the probe velocity is developed, and six independent visual features are proposed to control the six degrees of freedom of the robot. In order to endow the system with the capability of automatically interacting with objects of unknown shape, a model-free visual servoing is developed. For that, we propose an efficient online estimation method to identify the parameters involved in the interaction matrix. Results obtained in both simulations and experiments validate the methods presented in this paper and show their robustness to different errors and perturbations, especially those inherent to the noisy US images. Index Terms—Medical robotics, model-free servoing, modeling, ultrasound (US) imaging, visual servoing.

Abstract — A new visual servoing method based on B-mode ultrasound images is proposed to automatically control the motion of a 2D ultrasound probe held by a medical robot in order to reach a desired B-scan image of an object of interest. In this approach, combinations of image moments extracted from the current observed object cross-section are used as feedback visual features. The analytical form of the interaction matrix, relating the time variation of these visual features to the probe velocity, is derived and used in the control law. Simulations performed with a static ultrasound volume containing an egg-shaped object, and in-vitro experiments using a robotized ultrasound probe that interacts with a rabbit heart immersed in water, show the validity of this new approach and its robustness with respect to modeling and measurements errors. Index Terms — Visual servoing, ultrasound, image moments, medical robotics.

Computational grids are enabling collaboration between scientists and organizations to generate and archive extremely large datasets across shared, distributed resources. There is a need to visually explore such data throughout the life-cycle of projects. Practical exploration of large datasets requires visualization tools that can function in the same grid environment in which the data is created and stored. Resource management interfaces are an important structural component of grid computing environments because they enable uniform access to the wide variety of resources necessary for scientific work. We describe a new advancereservation system for graphics resources; and an application of existing grid technology to create general-purpose active storage systems. We report our experience with prototype infrastructure and application components, involving experiments coupling end-to-end resources for interactive visual exploration of large data in representative distributed environments.

In this paper we present a technique for tracking borescope tip pose in real-time. While borescopes are used regularly to inspect machinery for wear or damage, knowing the exact location of a borescope is difficult due to its flexibility. We present a technique for incremental borescope pose determination consisting of off-line feature extraction and on-line pose determination. The offline feature extraction precomputes from a CAD model of the object the features visible in a selected set of views. These cover the region over which the borescope should travel. The on-line pose determination starts from a current pose estimate, determines the visible model features, and projects them into a two-dimensional image coordinate system. It then matches each to the current borescope video image (without explicitly extracting features from this image), and uses the differences between the predicted and matched feature positions in a least squares technique to iteratively refine the pose estimat...