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Item 3D Scene Comparison using Topological Graphs(The Eurographics Association, 2007) Paraboschi, L.; Biasotti, S.; Falcidieno, B.; Raffaele De Amicis and Giuseppe ContiNew technologies for shape acquisition and rendering of digital shapes have simplified the process of creating virtual scenes; nonetheless, shape annotation, recognition and manipulation of both the complete virtual scenes and even of subparts of them are still open problems. In this paper we deal with the problem of comparing two (or more) object sets, where each model is represented by an attributed graph. We will define a new distance to estimate the possible similarities among the sets of graphs and will validate our work using the shape graph [BGSF06].Item Product Design, Reverse Engineering, Rapid Prototyping - a Case Study in Cutlery Production(The Eurographics Association, 2007) Magrassi, Grazia; Bordegoni, Monica; Raffaele De Amicis and Giuseppe ContiReverse Engineering and Rapid Prototyping are consolidated practices in the industrial product design process. In any case, best practices should be set up according to the type of product and of objectives. This paper presents the results of a product re-engineering application in the field of high quality stainless steel cutlery. This activity included a re-modeling of a basis-shape that reproduces at best the original shape of a cutlery set designed in the Thirties for Alessi, which is still considered to be very fashionable. The shape of the manufactured physical pieces of cutlery has changed in time in respect to the original design, mainly because of some problems related to their manufacturing, which has been transferred from the central plant to other branches. We have obtained the digital model of the pieces of cutlery on the basis of the analysis of the available original 2D drawings, and of the laser scanning and subsequent re-engineering design of the available manufactured objects. Particularly complex activity was the removal of the shapes deviations due to the different forming techniques used in the various production factories. At the end of the reconstruction activity, physical prototypes of the new models were produced by means of a sintering process in order to evaluate and compare them to the original ones.Item Rendering Order Optimization for SVGStat Improvement(The Eurographics Association, 2007) Battiato, Sebastiano; Puglisi, Giovanni; Raffaele De Amicis and Giuseppe ContiVector representation of digital images offers a number of advantages over the more common raster representation, such as scalability and resolution independence. Many efforts have been made to deploy scalable raster standards for photographic imagery addressed to portable applications. However, they lack the flessibility and simplicity of vector representation. Vector graphics is a new and little explored alternative to the more common representation. In this paper we present our raster to vector technique, called SVGStat, improved with a new boundaries simplification algorithm.Item The Dance of the Air: a Case Study in Interactive Digital Art(The Eurographics Association, 2007) Cuoghi, E.; Gherardi, R.; Toldo, R.; Raffaele De Amicis and Giuseppe ContiThis paper describes the conception and realization of an interactive art installation called The Dance of the Air . The whole process is taken as a case study for the different challenges encounteredduring the implementation of the system. The project is followed from the seminal idea to the artistic specifications, the translation into technical requirements and the final deployment step.Item Techniques for Computer Assisted Surgery(The Eurographics Association, 2007) Turini, G.; Pietroni, N.; Ganovelli, F.; Scopigno, R.; Raffaele De Amicis and Giuseppe ContiIn the recent decades robotic and computer science have been gaining more and more relevance in all aspects of our lives. In surgery, for example, they gave birth to procedures that would be impossible to perform otherwise (e.g. tele-surgery, nano-surgery). On this regard, these applied sciences already play an important role in assisting the surgeon both in the operative room and as a support in the education of young surgeons, but much work has still to be done. This paper presents some research and applicative results on Computer Assisted Surgery achieved in the framework of Endocas, a newly founded Center of Excellence in Pisa: a method for segmentation of anatomic parts from 3D dataset able to recover shapes from noisy 3D dataset; a technique for simulating bone drilling using a adaptive decomposition of tetrahedral meshes; a new open source library to support the implementation of techniques for simulating deformable objects.Item Ramses: a Visual Steganographic System(The Eurographics Association, 2007) Battiato, S.; Blasi, G. Di; Gallo, G.; Patti, S.; Raffaele De Amicis and Giuseppe ContiSteganography is the art of "secret communication". Its goal is to transmit a message (information) hidden inside another visible message. The typical visible message used in many steganographic systems is a digital image and the embedded message is usually hidden by working in the Fourier domain. In this paper we present Ramses, a novel approach to the steganography based on the Puzzle Image Mosaic (PIM) technique ( [DGP05]) which uses the metaphor of the hieroglyphicwriting to hide the message in the image. Themessage is first coded by a sequence of small irregular images and then merged inside another image together with many other small images.We prove that the Kerckhoff's principle required by a steganographic technique is satisfied and experimental results show how it is very difficult to detect the hidden message.Item Realtime Wavelet Video Encoding with Generic Graphics Processing Unit(The Eurographics Association, 2007) Stocklöw, Carsten; Noll, Stefan; Raffaele De Amicis and Giuseppe ContiWavelet video encoding with multi-resolution analysis is the base for a layered coding scheme. From one video source streams of different resolutions can be generated in one coding process. To reduce computing time the graphics processing unit (GPU) of a PC system is used for tasks of video compression. Color space conversion and wavelet transformation with just one single rendering pass for horizontal and for vertical decomposition were done be the GPU. Together with the CPU the GPU increases the computed frames per second and possible resolutions for live videos. Live broadcasting and interactive systems with streaming video like video conferencing are applications which take advantage from the proposed concept. This is especially interesting for live video encoding up to the high definition TV (HDTV) formats 720p and better.Item A Mixed Environment for Ergonomics Tests: Tuning of Stereo Viewing Parameters(The Eurographics Association, 2007) Bordegoni, Monica; Caruso, Giandomenico; Ferrise, Francesco; Giraudo, Umberto; Raffaele De Amicis and Giuseppe ContiVirtual Reality and related technologies are becoming a common practice in the design industry in general and more specifically in the automotive field. By the joined use of virtual prototyping methodologies it is possible to achieve the reduction of the time-to-market, as well as the costs deriving from the creation of physical prototypes. Ergonomics tests conducted in Virtual Reality environments can be successfully used to influence the design of products. We have set up a mixed reality environment that allows us to simulate and test postural aspects as well as various levels and modalities of users' interaction. In order to achieve a performing interaction, correct registration and visualization parameters must be carefully set for preventing possible interaction errors, such as pointing with precision to the assigned target. The paper presents a methodology for tuning stereoscopic properties of the mixed reality environments used for ergonomic tests of a car interior in order to achieve correct visualization and positioning parameters. The environment includes a virtual human controlled by an optical motion tracking system, physical objects onto which the graphic virtual environment is superimposed, and a rotatory haptic device for controlling the car on-board infotainment. interface.Item Real Positioning in Virtual Environments Using Game Engines(The Eurographics Association, 2007) Chiara, Rosario De; Santo, Valentina Di; Erra, Ugo; Scarano, Vittorio; Raffaele De Amicis and Giuseppe ContiImmersive virtual environments offer a natural setting for educational and instructive experiences for users, and game engine technology offers an interesting, cost-effective and efficient solution for building them. In this paper we describe an ongoing project whose goal is to provide a virtual environment where the real location of the user is used to position the user's avatar into the virtual environment.Item A Practical Vision Based Approach to Unencumbered Direct Spatial Manipulation in Virtual Worlds(The Eurographics Association, 2007) Bettio, Fabio; Giachetti, Andrea; Gobbetti, Enrico; Marton, Fabio; Pintore, Giovanni; Raffaele De Amicis and Giuseppe ContiWe present a practical approach for developing interactive environments that allows humans to interact with large complex 3D models without them having to manually operate input devices. The system provides support for scene manipulation based on hand tracking and gesture recognition and for direct 3D interaction with the 3D models in the display space if a suitably registered 3D display is used. Being based on markerless tracking of a user's two hands, the system does not require users to wear any input or output devices. 6DOF input is provided by using both hands simultaneously,making the tracker more robust since only tracking of position information is required. The effectiveness of the method is demonstrated with a simple application for model manipulation on a large stereo display, in which rendering constraints are met by employing state-of-the-art multiresolution techniques.