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Item Interactive Remote Exploration of Massive Cityscapes(The Eurographics Association, 2009) Benedetto, Marco Di; Cignoni, Paolo; Ganovelli, Fabio; Gobbetti, Enrico; Marton, Fabio; Scopigno, Roberto; Kurt Debattista and Cinzia Perlingieri and Denis Pitzalis and Sandro SpinaWe focus on developing a simple and efficient unified level-of-detail structure for networked urban model viewers. At the core of our approach is a revisitation of the BlockMap [CDG*07] data structure, originally introduced for encoding coarse representations of blocks of buildings to be used as direction-independent impostors when rendering far-away city blocks. The contribution of this paper is manifold: we extend the BlockMap representation to support sloped surfaces and input-sensitive sampling of color; we introduce a novel sampling strategy for building accurate BlockMaps; we show that BlockMaps can be used as a versatile and robust way to parameterize the visible surface of a highly complex model; we improve the expressiveness of urban models rendering by integrating an ambient occlusion term in the representation and describe an efficient method for computing it; we illustrate the design and implementation of a urban models streaming and visualization system and demonstrate its efficiency when browsing large city models in a limited bandwidth setting.Item Pushing Time-of-Flight Scanners to the Limit(The Eurographics Association, 2009) Callieri, Marco; Cignoni, Paolo; Dellepiane, Matteo; Scopigno, Roberto; Kurt Debattista and Cinzia Perlingieri and Denis Pitzalis and Sandro SpinaThe paper describes a pipeline for 3D scanning acquisition and processing that allow to exploit the utmost precision and quality out of ToF scanners. The proposed approach capitalize on the knowledge of the distribution of the noise to apply sophisticated fairing techniques for cleaning up the data. Leveraging on the very dense sampling of this kind of scanners we show that is possible to attain high accuracy. We present a practical application of the proposed approach for the scanning of a large (5mt) statue with millimetric precision.Item Artifacts Removal for Color Projection on 3D Models using Flash Light(The Eurographics Association, 2009) Dellepiane, Matteo; Callieri, Marco; Corsini, Massimiliano; Cignoni, Paolo; Scopigno, Roberto; Kurt Debattista and Cinzia Perlingieri and Denis Pitzalis and Sandro SpinaAbstract Lighting artifacts are one of the main issues in digital photography: complex light setups are needed to attenuate or remove them. Flash light is a very easy way to illuminate an object or an environment, but it is rarely considered in most of the Computer Graphics and Computer Vision applications. This is due to the big amount of artifacts introduced by this lighting, and to the difficulty in modeling its behavior. In this paper we present a simple method to use flash light in the context of color acquisition and mapping on 3D models. We propose a simple way to accurately estimate the flash position with respect to the camera, and we propose two automatic methods to detect and remove artifacts from a set of images which are registered to a 3D model. These methods are integrated in the context of a color mapping framework. The results show that it is possible to obtain high quality colored 3D models using flash light, which is the most simple illumination setup. This results are extremely important especially in the context of Cultural heritage, where the acquisition of color has often to be performed on site, without a specific lighting setup.