Als Saureamidacetale, Harnsto5acetale und Lactamacetale werden Verbindungen bezeichnet, in denen die CO-Gruppe der Carbonsaureamide, Harnstoffe und Lactame durch die C(OR)+ruppe ersetzt ist. Es werden Darstellung und Eigenschaften dieser neuen, ungemein reaktionsfahigen Korperklassen beschrieben. Im Gegensatz zu den ihnen zugrunde liegenden Carbonylverbindungen reagieren sie rnit gr6lDter Leichtigkeit und ohne Mitwirkung eines Katalysators mit allen nucleophilen Agenzien, insbesondere kondensieren sie rnit allen Verbindungen rnit reaktiver CH3-oder CHz-Gruppe unter Bildung von Aminoalkyliden-Verbindungen. Diese groI3e Reaktionsfahigkeit wird zuriickgefilhrt auf die Fahigkeit der Slureamidacetale, Harnstoffacetale und Lactamacetale zur Ionisation unter Bildung von Carbonium-Oxonium-Imonium-alkoholaten. Bei einigen dieser Verbindungen gibt sich diese Ionisationsfahigkeit durch eine wenn auch nur geringe elektrische Leitfahigkeit in geeigneten organischen Losungsmitteln zu erkennen.
We describe a new method to register surface data measured by optical three-dimensional (3-D) sensors from various views of an object. With our method, complete 3-D models of objects can be generated without user interaction. Circumferential acquisition of 3-D objects is done by taking several views from different directions. To generate a complete 3-D-model, the views must be aligned with each other. This process is called registration and is commonly done interactively by searching for so-called corresponding points in the different views and by use of these points to calculate the appropriate rotation and translation. Our approach is based on automatically finding points that are eye catching or salient compared with other surface points. We derive a quantitative measure of point salience and a feature definition for free-form surfaces by introducing a concept to measure pragmatic information. Experiments confirm that our salient points can be robustly located on general free-form surfaces, even if there are no corners or edges. Furthermore, the neighborhoods of the salient points are highly distinguishable from each other. This results in a large reduction of the complexity of the subsequent geometric matching. The computing time is only a few seconds. We present results from various fields of application.
The 3D reconstruction method enables an effective tool to relate a tracking system to a FD-CT imaging system and provide adequate accuracy for most navigation applications.
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