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Alkanethiols CHsfCtLin-iSH (Cn, n = 4, 6, 8, 10) were self-assembled from ethanolic solutions onto a single-crystal Au( 111) surface and characterized using an ultrahigh vacuum scanning tunneling microscope (STM). Short-chain homologues (C4 and Cg) exhibited a two-dimensional (2-D) liquid phase at room temperature. Facile mass transport of surface gold atoms was observed in the presence of the liquid phase. The short-chain homologues exhibited slow desorption of surface thiolate which led to the nucleation and growth of ordered domains having a unit cell of px J3 (8 < p < 10). No 2-D liquid phase was observed for longer chain homologues (Cs and C10).

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image acquisition systems are rapidly becoming more affordable, especially systems based on commodity electronic cameras. At the same time, personal computers with graphics hardware capable of displaying complex 3D models are also becoming inexpensive enough to be available to a large population. As a result, there is potentially an opportunity to consider new virtual reality applications as diverse as cultural heritage and retail sales that will allow people to view realistic 3D objects on home computers. Although there are many physical techniques for acquiring 3D data-including laser scanners, structured light and time-of-flight-there is a basic pipeline of operations for taking the acquired data and producing a usable numerical model. We look at the fundamental problems of range image registration, line-of-sight errors, mesh integration, surface detail and color, and texture mapping. In the area of registration we consider both the problems of finding an initial global alignment using manual and automatic means, and refining this alignment with variations of the Iterative Closest Point methods. To account for scanner line-of-sight errors we compare several averaging approaches. In the area of mesh integration, that is finding a single mesh joining the data from all scans, we compare various methods for computing interpolating and approximating surfaces. We then look at various ways in which surface properties such as color (more properly, spectral reflectance) can be extracted from acquired imagery. Finally, we examine techniques for producing a final model representation that can be efficiently rendered using graphics hardware.

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AbstractÐThe creation of three-dimensional digital content by scanning real objects has become common practice in graphics applications for which visual quality is paramount, such as animation, e-commerce, and virtual museums. While a lot of attention has been devoted recently to the problem of accurately capturing the geometry of scanned objects, the acquisition of high-quality textures is equally important, but not as widely studied. In this paper, we focus on methods to construct accurate digital models of scanned objects by integrating high-quality texture and normal maps with geometric data. These methods are designed for use with inexpensive, electronic camera-based systems in which low-resolution range images and high-resolution intensity images are acquired. The resulting models are well-suited for interactive rendering on the latest-generation graphics hardware with support for bump mapping. Our contributions include new techniques for processing range, reflectance, and surface normal data, for image-based registration of scans, and for reconstructing high-quality textures for the output digital object.

We describe a project to create a three-dimensional digital model of Michelangelo's Florentine Pietà. The model is being used in a comprehensive art-historical study of this sculpture that includes a consideration of historical records and artistic significance as well as scientific data. A combined multi-view and photometric system is used to capture hundreds of small meshes on the surface, each with a detailed normals and reflectance map aligned to the mesh. The overlapping meshes are registered and merged into a single triangle mesh. A set of reflectance and normals maps covering the statue are computed from the best data available from multiple color measurements. In this paper, we present the methodology we used to acquire the data and construct a computer model of the large statue with enough detail and accuracy to make it useful in scientific studies. We also describe some preliminary studies being made by an art historian using the model. CR Categories I.

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