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Camera based system for measuring dental arc morphology
Orthometrics is a 3-D measurement system designed for professional use in dental research. It is suitable for measuring distances and angles between morphologically interesting points on dental crowns. The measurements are performed using plaster models of jaws where the points are marked by small dots. The distances and angles are obtained in three-dimensional domain which allows also the depth information to be exploited.
The measurement system consists of one video camera, frame grabber, stand and PC. The stand holds the camera in a fixed position, and allows the plaster model to be turned in five different orientations. The camera used is a standard off-the-shelf CCD camera, which is calibrated with high precision. The accuracy of the resulting point locations in each dimension is better than 0.1 mm.
The measurement session is started by capturing five digital images from the target. The locations and the correspondences of the measurement points are then determined by picking them manually from the images. The amount of laborious human intervention is minimized by a smart and easy to use graphical user interface. After the manual stage, the measurement software takes care of the rest of the processing. The 3-D structure, distances and angles are now computed automatically based on the measurement plan. The results are visualized in the user interface and they can be saved as an ascii file, which is accessible, for example, by Microsoft Excel. Also, the camera calibration procedure included in the system is fully automatic.
The software package is completely free and it can be downloaded here. It runs under Windows NT 4.0 and Windows 95. The GUI is compiled with Borland C++ 5.0, the computation and calibration modules are generated from MATLAB code with MATCOM translator. Testing the software does not require any special equipment, because there are some example images included in the package. You can try them, and if you are interested to get the hardware, send email to Dr. Pertti Pirttiniemi from the Department of Dentistry, University of Oulu.
Click the pictures below to see what Orthometrics looks like.
camera + stand:
Department of Dentistry
- Pertti Pirttiniemi
- Kirsi Pirilä
Department of Information Processing Science
- Jari Granroth
- Janne Kiiskilä
- Arto Oinas
- Antti Peteri
Department of Electrical Engineering