Italian Chapter Conference 2006

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3D CT Segmentation for Clinical Evaluation of Knee Prosthesis Operations
(The Eurographics Association, 2006) Battiato, S.; Bosco, C.; Farinella, G. M.; Impoco, G.; S. Battiato and G. Gallo and F. Stanco
In surgical knee replacement, the damaged knee joint is replaced with artificial prostheses. An accurate clinical evaluation must be carried out before applying knee prostheses to ensure optimal outcome from surgical operations and to reduce the probability of having long-term problems. Useful information can be inferred from CT scans of the knee area, that can be used to estimate the stress that will be acting on the prosthesis being implanted. This information can be exploited to tailor the prothesis to the patient s anatomy. We present some ideas for a system intended to help surgeons in evaluating the post-operative outcome of knee prosthesis implantation. We also show some preliminary results about the 3D segmentation of CT data, that is the main activity of our lab in the project.
3D data segmentation using a non-parametric density estimation approach
(The Eurographics Association, 2006) Castellani, U.; Cristani, M.; Murino, V.; S. Battiato and G. Gallo and F. Stanco
In this paper, a new segmentation approach for sets of 3D unorganized points is proposed. The method is based on a clustering procedure that separates the modes of a non-parametric multimodal density, following the mean-shift paradigm. The main idea consists in projecting the source 3D data into a set of independent sub-spaces, forming a joint multidimensional space. Each sub-space describes a geometric aspect of the data set, such as the normals and principal curvatures, so as a dense region in a particular sub-space indicates a set of 3D points sharing a similar value of that feature. A non-parametric clustering method is applied in this joint space by using a multidimensional kernel. This kernel smoothly takes into account for all the subspaces, moving towards high density regions in the joint space, separating them and providing "natural" clusters of 3D points. The algorithm can be implemented very easily and only few parameters need to be freely tuned. Experiments are reported, both on synthetic and real data, assessing the quality of the proposed approach and promoting further developments.
3D Input devices integration in CAD environment
(The Eurographics Association, 2006) Bruno, F.; Caruso, G.; Muzzupappa, M.; S. Battiato and G. Gallo and F. Stanco
Virtual Reality (VR) technologies are becoming commonly used tools in the product development process, starting from the styling review in the conceptual design phase, until to the Digital Mock-up (DMU) validation in the advanced stages of the design process. What has not yet been sufficiently investigated is the possibility to interact with the DMU directly inside the CAD environment using 3D input devices. Although few CAD systems, like CATIA V5, have an additional module to support VR devices, in most cases it is still necessary to customize the application to obtain the functionalities desired by the user. The present paper discusses difficulties and advantages related to the integration of VR techniques and 3D input devices in CAD systems. The work has been conducted analyzing and testing the potentialities of the Unigraphics NX3 CAD environment and implementing a software plug-in that allows the user to perform such interaction tasks employing 3D input devices.
Adaptive Frame Rate Up-conversion with Motion Extraction from 3D Space for 3D Graphic Pipelines
(The Eurographics Association, 2006) Falchetto, M.; Barone, M.; Pau, D.; S. Battiato and G. Gallo and F. Stanco
A novel 3D Graphic Pipeline for mobile handheld devices is introduced. It s able to achieve increased frame-rate at its output, high picture quality, improved temporal anti-aliasing, thanks to frame-rate upconversion algorithm based on primitive s motion extraction and efficient compensation. Classic rendering process doesn t exploit spatial and temporal coherence of the motion: each frame is rendered by using a lot of the pipeline resources inside geometry, rasteriser and fragment processing stages. Moreover each frame is computed independently from the temporal adjacent one with a brute force approach. Video based algorithms instead (e.g. MPEG type of processing), heavily exploit temporal, spatial and statistical coherency of the content being coded, relying on motion estimation to extract motion vectors from pixel domain during coding process and apply them during motion compensation decoding process. Previous works on 3D graphics were based on the use of impostors, sprite or coherent layers. Those approaches are too much complex and requires high computational power. Other ones based on frame averaging are too much simple: they achieve poor spatial and temporal quality and artifacts become clearly visible as the motion dynamic increases. Proposed approach instead exploits motion temporal coherency by extracting motion vectors from motions of visible primitives in screen space. Temporal coherence has been exploited between key frames using an adaptive motion compensated stage. This method is able to reconstruct the frames without introducing noticeable artifacts on final pictures. Results achieved are 10-15 dB better quality than simple temporal frame average and show a natural motion with no annoying artifacts like real video content shows.
An Architecture for Distributed Behavioral Models with GPUs
(The Eurographics Association, 2006) Chiara, R. De; Erra, U.; Scarano, V.; S. Battiato and G. Gallo and F. Stanco
We describe an architecture for massive simulation of a distributed behavioral model using graphics hardware. By leveraging on the recent programmable capabilities of GPUs we implemented the model capable of managing a large aggregate motion of birds in a virtual environment that can avoid both static and dynamic obstacles. We demonstrate the effectiveness of our GPU implementation by comparing the results to a CPU implementation and, emphasize the modularity of the proposed architecture that favors reusability in several contexts.
Color Palette Images Re-indexing by Self Organizing Motor Maps
(The Eurographics Association, 2006) Battiato, S.; Rundo, F.; Stanco, F.; S. Battiato and G. Gallo and F. Stanco
Palette re-ordering is a well known and very effective approach for improving the compression of color-indexed images. If the spatial distribution of the indexes in the image is smooth, greater compression ratios may be obtained. As known, obtaining an optimal re-indexing scheme is not a simple problem. In this paper we provide a novel algorithm for palette re-ordering problem showing the advantages of using a neural network instead of classical heuristic methods. We propose to apply the Motor Map neural network which is considered an extension of the well-known SOM Kohonen neural network. Experiments confirm the effectiveness of the proposed technique.
Compressed SVG Representation of Raster Images Vectorized by DDT Triangulation
(The Eurographics Association, 2006) Battiato, S.; Greco, F.; Nicotra, S.; S. Battiato and G. Gallo and F. Stanco
This paper presents a portable compression algorithm applied to raster data images properly triangulated by using DDT (Data Dependent Triangulation). In particular the input source data are encoded to be rendered by standard SVG (Scalable Vector Graphics) engine. The proposed compression strategy works reducing the overall entropy implementing some heuristic strategies to properly re-code the redundancy inside the mesh representation. The compressed data are enclosed into an SVG player able to both decompress and show the original image. Results show the effectiveness of the approach.
Data-Driven Facial Feature Morphing for 3D Face Synthesis
(The Eurographics Association, 2006) Zhang, Yu; S. Battiato and G. Gallo and F. Stanco
This paper presents a data-driven method for synthesizing new realistic 3D human faces by morphing a set of facial features. The method takes as examples 3D scanned human face models in order to exploit the shape variations presented in the real faces of individuals. We automatically compute a vertex-to-vertex correspondence between the unregistered face scans by deforming a generic mesh to fit the specific person s face geometry in a global-tolocal fashion. Exploiting the statistics of the generated datasets of feature shapes we transform them into vector space representations by applying a principal component analysis (PCA). Our feature shape morphing model is formed as a linear combination of the main modes of feature shape variations. We introduce a shape smoothing and blending method for generating a seamlessly deformed mesh around the feature borders. We demonstrate our method by combining 3D morphing of four features to generate a wide range of different face shapes.
DentroTrento: an Example of Application of Computer Graphics to the Evolution of the Archaeological Site of Tridentum
(The Eurographics Association, 2006) Piffer, S.; Conti, G.; Girardi, G.; Ucelli, G.; Amicis, R. De; S. Battiato and G. Gallo and F. Stanco
This paper illustrates the DentroTrento project, commissioned by the local authority for Cultural Heritage, which has lead to the creation of an edutainment system for the visitors of an archaeological site in the town of Trento. In particular, the aim of the project was to enhance the didactic and entertaining potential of a Roman archaeological site which is located between the Theatre s foundations through the development of a computer graphics-based application capable of high visual and emotional impact. This has been made possible through the creation of an interactive system where the virtual reconstruction becomes the main means of guiding the visitor through a virtual walk across time. The relevance of the work illustrated is underlined by the profile of the project and the nature and importance of the site, which is located underground below a square. In fact this circumstance does not let the visitor perceive the urban outline of the roman town nor it lets visitors fully perceive, through the use of traditional teaching material, the way of life typical of the time. The system proposed instead engages the visitor into a more exciting experience replicating, not only the architecture, but the way of life of the Roman town. The scope of the project together with the heterogeneity of the working team has required a rigorous approach to the management of the entire project.
Designing a Virtual Reality Game for the CAVE
(The Eurographics Association, 2006) Livatino, S.; Agerbech, V.; Johansen, A.; Johansen, B.; S. Battiato and G. Gallo and F. Stanco
Virtual Reality has for many years been a technology which has stagnated in application and software development for games. The applications available for VR environments have increased but they mostly remain related to scientific purposes while computer games in VR are still being developed and only show a part of their actual potential. The game industry has begun to see the possibilities of VR games in a near future with the implementation of some popular games to a CAVE system. However, a full immersion VR solution still remains uncommon and expensive. This paper aims to demonstrate the potential of VR games, and in particular games for the CAVE, now that affordable solutions are close to reach as more powerful hardware is available at low price. The focus is also on the methodology to be pursued while designing a VR game. Results were encouraging and tests performed on a first prototype demonstrates system feasibility.
Easy Access to Huge 3D Models ofWorks of Art
(The Eurographics Association, 2006) Callieri, M.; Ponchio, F.; Cignoni, P.; Scopigno, R.; S. Battiato and G. Gallo and F. Stanco
Automatic shape acquisition technologies evolved rapidly in recent years, and huge mass of 3D data can be easily produced. The high accuracy of range scanning technology makes the Cultural Heritage domain one of the ideal fields of use of these devices. Given this particular application domain, two issues arise: how to visualize at interactive rates these complex data on commodity computers (both locally and on web), and how to improve the ease of use of the visualization tools (as potential users are often not expert with interactive graphics). We present a new visualization system designed to support easy implementation of multimedia kiosk for museums or expositions, which has also been extended to web-based usage. The system allows naive users to inspect a large complex 3D model at interactive frame rates on off-the-shelf PC s, presenting the 3D model and all the multimedia data that has been linked to selected points of its surface. A main goal in the design of the system was to provide the user with a very easy and natural interaction approach, based on a straightforward "point and click" metaphor. Visualization efficiency is obtained by adopting a continuous level-of-detail (LOD) representation, where on-line automatic selection of the best-fit level of detail (according to the current view frustum) is coupled with visibility culling and ready-to-render representation of the geometry.
An Experimental Setup to Evaluate the Performance of Tone Mapping Algorithms
(The Eurographics Association, 2006) Marsi, S.; Impoco, G.; Ukovich, A.; Ramponi, G.; S. Battiato and G. Gallo and F. Stanco
Many algorithms have been proposed in the literature to solve the problem of mapping tones from high dynamic range sources to low dynamics displays, while preserving the information conveyed by the original scene. Methods and tools to evaluate the performance of tone mapping algorithms are needed. Some experiments have recently been presented involving human observers. In this paper, we propose method not relying on human scoring. Wellilluminated reference pictures of challenging scenes are captured and used as references. Low-quality shots of the same scenes are enhanced using some tone mapping algorithms and the outcome is compared to the reference images using a standard colour distance measure. The results clearly favour the more sophisticated local methods.
From Skull to Face: an Improved Framework for Ethnically Faithful 3D Face Reconstruction
(The Eurographics Association, 2006) Abate, A. F.; Nappi, M.; Ricciardi, S.; Sabatino, G.; S. Battiato and G. Gallo and F. Stanco
3D imagery can be a useful tool for archaeologists and anthropologists committed to the study of ancient people, helping them to better visualize the results of their theories and findings. This paper presents a methodology to generate a tridimensional model of a compatible face from its skull, and is specifically aimed to archaeological/anthropological applications. The proposed approach to facial reconstruction, that relies on craniometrical analysis and content based image retrieval technology, has two main purposes: to achieve a more ethnically faithful reproduction of main facial features respect to other techniques based on statistical data, and to allow a plausible reproduction of important physiognomic features (such as eyes, nose, lips, ears and hairs) which can t be inferred from the skull. The facial reconstruction of a female subject found in the archaeological site of Murecine (Pompei) who found death during the volcanic eruption in 79 a. C. is presented as a case study.
GPU based direct illuminance values computation for interactive lighting CAD
(The Eurographics Association, 2006) Selmo, D.; Musante, F.; Rossi, M.; S. Battiato and G. Gallo and F. Stanco
In this work we focus our attention on real-time direct illuminance values computation using dedicated 3D graphics hardware compatible with OpenGL 2 standard. Our method works with real light intensity distribution measured for lighting fixtures by enconding it in a texture for GPU data comunication. Illuminance values are reprensented in real-time by using a perceptual based colour scale. Illuminance computation is limited to direct light. This is not a severe limitation for exterior and road lighting design, and nevertheless it is a useful project parameter for interior lighting design too.
Hand Made 3d Modelling for the Reconstructive Study of Temple C in Selinunte : Preliminary Results
(The Eurographics Association, 2006) Gabellone, F.; S. Battiato and G. Gallo and F. Stanco
This paper illustrates the preliminary results of the virtual reconstruction of temple C in Selinunte. The reconstruction was undertaken as part of the Land-Lab Project launched by the University of Lecce in 2003 for the promotion and appropriate exploitation of the cultural, historic, artistic and archaeological heritage of two Italian regions, Puglia and Sicily, using advanced technologies. The reconstruction of temple C was launched with the help of numerous experts in the field of surveying and representation, as well as art historians, archaeologists and architects, following a fully multidisciplinary approach. The reconstructive study was conducted in a 3D environment mainly using NURBS modelling, Subdivision Surfaces and sub-polygonal displacement. Our reconstructive approach, which might be defined numerical, makes it possible to recompose, at least in the initial phases of the work, all the surveyed architectural elements in accordance with a procedure based on digital anastylosis. The reconstruction of the monument represents a contribution to the study of Doric architecture in southern Italy conducted with the help of modern technologies.
Implementing Mesh-Based Approaches for Deformable Objects on GPU
(The Eurographics Association, 2006) Ranzuglia, G.; Cignoni, P.; Ganovelli, F.; Scopigno, R.; S. Battiato and G. Gallo and F. Stanco
These latest years witnessed an impressive improvement of graphics hardware both in terms of features and in terms of computational power. This improvement can be easily observed in computer games, where effects which, until few years ago, could only be achieved with expensive CPU computation are now shown interactively. Although the GPU has been designed for implementing graphics effects, it is still it basically a processing unit with its own memory, and, being specialized for algebraic tasks, supplies a number of floating point operations per second which is orders of magnitude greater than the CPU. This suggested to the graphics community that the GPU could also be used for general purpose computation and a number of papers have been published on how to hack the GPU to this target. Following this trend we propose a framework for using GPU for implementing techniques for deformable objects represented as generic meshes. The framework only assumes than the global computation is the union of local computations, which is true for all the explicit methods.
Maya Sun Simulation of Bosnian Gravestone Virtual Model
(The Eurographics Association, 2006) Rizvic, S.; Sadzak, A.; Avdagic, Z.; Chalmers, A.; S. Battiato and G. Gallo and F. Stanco
Bosnia and Herzegovina is very rich with cultural heritage sites. Perhaps the most famous of these are the stecaks; the monumental gravestones of Bosnian Heretic Christians. The orientation of the stecaks was important to the ancient Bosnians, Unfortunately, their orientation towards the sun has been changed when they were moved from their original locations to more secure sites at museums. This is particularly true of the stecak from Donje Zgosce, one of the most beautiful stecaks in B&H. Using high-fidelity graphics techniques we have created a detailed virtual reconstruction of this stecak and produced a sun simulation in Maya This enables archaeologists to be able to investigate the interaction of the light with the stecak s carvings as it may have appeared in 14th century.
A Message-Based Annotation System for Collaborative Design Review
(The Eurographics Association, 2006) Witzel, M.; Conti, G.; Amicis, R. De; S. Battiato and G. Gallo and F. Stanco
The paper illustrates a shared annotation mechanism developed within a collaborative virtual environment for design review. This represents one of the first prototypes being developed within the European Project IMPROVE and it has been designed to be used within two distinct industrial scenarios: automotive and architectural design. The key feature of the system is that its functionalities (modelling, rendering, tracking) are distributed across a network of computers performing specific tasks and that the communication among these takes place through a standardised data message exchange. This paper shows the effectiveness of this approach by focusing on the implementation of the distributed annotation feature.
Multi-Modal Presentation of Work of Arts in Virtual Reality with Simulation of Multi-Mirror Reflection
(The Eurographics Association, 2006) Livatino, S.; Cuciti, D.; Wojciechowki, A.; S. Battiato and G. Gallo and F. Stanco
The use of different media such as photography and virtual reality combined with different presentation modalities may provide a user with an extraordinary tool for exploration and appreciation of real work of art. This is especially important in case of time-spatial works-of-art where the problem of functionalities presentation becomes much more demanding. The possibility offered by latest graphics machines has attracted the interest of researchers to investigate this new area. The goal of the presented work is the creation of a multi-modal presentation of a piece of contemporary art, tightening the relation between computer graphics and arts. The focus is on an application that it is capable to cope in real-time with simulation of mirror reflections, including multi-reflections. The results were very encouraging which led to optimistic conclusions with a wide range of options for future works.
Multi-resolution Morphological Representation of Terrains
(The Eurographics Association, 2006) Danovaro, E.; Floriani, L. De; Vitali, M.; Papaleo, L.; S. Battiato and G. Gallo and F. Stanco
Mesh-based terrain representations provide accurate descriptions of a terrain, but fail in capturing its morphological structure. The morphology of a terrain is defined by its critical points and by the critical lines joining them, which form a so-called surface network. Besides being compact, a morphological terrain description supports a knowledge-based approach to the analysis, visualization and understanding of a terrain dataset. Moreover, because of the large size of current terrain data sets, a multi-resolution representation of the terrain morphology is crucial. Here, we address the problem of representing the morphology of a terrain at different resolutions. The basis of the multi-resolution terrain model, that we call a Multi-resolution Surface Network (MSN), is a generalization operator on a surface network, which produces a simplified representation incrementally. An MSN is combined with a multi-resolution mesh-based terrain model, which encompasses the terrain morphology at different resolutions. We show how variable-resolution representations can be extracted from an MSN, and we present also an implementation of an MSN in a compact encoding data structure.

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