New method to analyze resolution acquisition for intraoral scanners

International audienceIn dentistry, 3D intraoral scanners (IOSs) are gaining increasing popularity in the production of dental prostheses. However, the quality of an IOS in terms of resolution remains the determining factor of choice for the practitioner; a high resolution is a quality parameter that can reduce error in the production chain. To the best of our knowledge, the evaluation of IOS resolution is not clearly established in the literature. This study provides a simple assessment of resolution of an IOS by measuring a reference sample and highlights various factors that may influence the resolution. A ceramic tip was prepared to create a very thin object with an edge smaller than the current resolution stated by the company. The sample was scanned with microCT (micro-computed tomography) and an IOS. The resulting meshes were compared. In the mesh obtained with the IOS, the distance between two planes on the edge was approximately 100 micrometers, and that obtained with microtomography was 25 micrometers. The curvature values were 27.46 (standard deviation – SD) 14.71) μm−1 and 5.18 (SD 1.16) μm−1 for microCT and IOS, respectively. These results show a clear loss of information for objects that are smaller than 100 μm. As there is no normalized procedure to evaluate resolution of IOSs, the method that we have developed can provide a positive parameter for control of IOSs performance by practitioners

READ. Recognition and Documentanalysis. Version 1.2 Final report

The aim of the READ project is the improvement of automatic manufacturing of forms and recognition technology. Brainwork of CGK besides this concentrates upon camera-imaging methods and upon using of color informationin order to improve intelligent character recognition on documents. By expansion of existing applications - color processing on document reading and color based document analysis - new demands arise on recognition technology, calling for significant extensions of existing and modern processing. Therefore easy adaptability and robustness of these proceedings has to be in the limelight. Reading- and recognition process applied to documents are very strong depending on the generated image quality with the scanner and on the applied imaging. Just in domain of documents, distinguesed by a relative firm given layout structure, a large potential of mechanical processing will arise. Outgoing from these problems two priority subjects hav ebeen choosen of CGK 1. Color scanner It was our aim, making a high grade image source for document and blank forms imaging available for. On this occasion color quality of the images in their detailed structure was placed into the foreground, since exactly the color has to be used as important information support to segmentation process. 2. Color based object segmentation By suited instructions of color parameters a method was developed, which makes it possible to separate foreground- and background-informations on blank forms. Reduction of image data quantity will taken over from the image processing (inside of the scanner), since otherwise huge data volume will arise, which only can be difficult managed. Furthermore, based on the color information of blank forms, a method was developed, making a color based type recognition on a blank form possible. (orig.)SIGLEAvailable from TIB Hannover: F98B2079+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman