TAILIEUCHUNG - MECHANICAL DIGITIZING FOR PALEONTOLOGY - NEW AND IMPROVED TECHNIQUES

Problems of nonholonomic mechanics, including many problems in robotics, wheeled vehicular dynamics and motion generation, have attracted considerable attention. These problems are intimately connected with important engineering issues such as path planning, dynamic stability, and , the investigation of many basic issues, and in particular, the role of symmetry in such problems, remains an important subject today. Despite the long history of nonholonomicmechanics, the establishment of pro- ductive links with corresponding problems in the geometric mechanics of systems with configuration-space constraints (., holonomic systems) still requires much development. The purpose of this work is to bring these topics closer together with a focus on nonholonomic systems with symmetry. Many of. | Palaeontologia Electronica http MECHANICAL DIGITIZING FOR PALEONTOLOGY - NEW AND IMPROVED TECHNIQUES Heinrich Mallison Alexander Hohloch and Hans-Ulrich Pfretzschner ABSTRACT Three-dimensional digitized representations of bones offer several advantages over real bones or casts. However creation of 3D files can be time consuming and expensive and the resulting files are difficult to handle due to their size. Mechanical digitizing was hitherto limited to large bones. Here new and improved data collection techniques for mechanical digitizers are described facilitating file creation and editing. These include - Improvements to the in-program digitizing procedure reducing time and financial demands. - Specifics for an easy to assemble and transportable holder for small fossils. - A significant increase in the size range of digitizable bones allowing both exact digitizing of bones only a few centimeters long and bones larger than the range of the digitizer. This increase allows the study of assemblages including both small and large bones. - Complex shapes such as costae and vertebrae can now be digitized with ease. - Step-by-step directions for digitizer and program use to facilitate easy acquisition of the techniques. 3D-files of fossils digitized with these methods can be added to online databases easily as small-scale preview and complete files. The file formats are common and the file sizes relatively small in comparison to CT or laser-scan data. Pointcloud files can be used interchangeably with laser-scan files of similar resolution. Other possible uses for mechanical digitizing data are described. Additionally techniques to extract and edit comparable data from CT scans are briefly described. CT-based data is used to check the accuracy of mechanically digitized data. Heinrich Mallison. Institut fur Geowissenschaften Eberhard-Karls-Universitat Tubingen Sigwartstrasse 10 72076 Tubingen Germany. Current address Museum fur Naturkunde - .

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