Optics: measuring and testing – Contour plotting
Patent
1992-01-30
1993-11-16
Rosenberger, Richard A.
Optics: measuring and testing
Contour plotting
356243, 356376, A61C 1904
Patent
active
052628353
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a method of making stereophotographic documentation and photogrammetric measurements of impressions or of models of jaws. The invention also relates to an apparatus useable for carrying out the method.
Within dentistry, plaster models are frequently made, which are used for visual screening and measurement of bite conditions (jaw properties), sliding callipers or the like being used for the measurement. According to current regulations, within a certain political jurisdiction about which the inventors are knowledgeable, jaw models belong to patient records and must be kept during a minimum period of three years. In most cases there is required a considerably longer storage time due to long time periods of treatment, which accordingly means that large storage spaces are needed for the plaster models during a long period of time.
Three-dimensional photographs of jaw models may to a certain extent replace plaster models. Such three-dimensional photographs may well be used for documentation, provided that measurements can be performed in these three-dimensional photographs. Thus, such photographs can be used for storage purposes instead of plaster models, which reduces the need of large storage spaces.
SUMMARY OF THE INVENTION
This invention relates to a photographic method that has been developed for documentation of jaw properties. Three-dimensional photographs are made from plaster models or impressions, the plaster models or the impressions being able to be documented in desired directions and perspectives. With the aid of computer programs desired distances and angles within the three-dimensional photographs of the jaws can be determined after measurement points have been digitized.
According to the invention, these purposes are achieved by a method of the kind mentioned by way of introduction, which in preferred practices, is characterized by the combination of the following features.
The impression or the model of a jaw is placed on a reference object which in its turn is placed on a base plate of a photographic apparatus comprising a camera mounted on a stand at a distance from the bottom plate and a light source for illuminating the article on the reference object;
One photograph of the impression or the model of a jaw is exposed with the aid of the camera when camera has taken a position at an angle distance from the vertical line, whereafter a second photograph is exposed of the impression or the model of a jaw when the camera has taken a corresponding position on the other side of the vertical line;
The two photographs are placed on a tray which is intended to cooperate with a stereoscope in such a way that the two exposed photographs may be viewed three-dimensionally in the stereoscope;
The photographs, in magnified condition, are brought to cooperate with a computer which is so programmed that three-dimensional coordinates for desired image points can be determined, which allows calculation of desired distances and angles.
BRIEF DESCRIPTION OF THE DRAWING
A preferred embodiment of an apparatus for carrying out the method is shown in the accompanying drawings, wherein:
FIG. 1 shows a stereophotographic apparatus according to the invention;
FIG. 2 shows the use of a stereoscope; and
FIG. 3 shows a reference object for use in practicing the method of the invention.
DETAILED DESCRIPTION
In FIG. 1 there is shown stereophotografic apparatus comprising a camera arranged on a stand 2. This stand 2 comprises a base plate 3 from which two generally vertical rods 4, 5 are placed at a distance from each other and have their upper parts connected by means of a plate 6 in which there is made an arched slot 7. The lower end of a generally vertical rod 8 is pivotably arranged in the base plate 3. The camera 1 is fastened to the upper end of the rod 8 and is directed towards the central portion of the base plate. The rod 8 is intended to cooperate with the plate 6 in such a way that it can be pivoted in the vertical plane between the outer pos
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patent: 4973114 (1990-11-01), Edwardson et al.
Wolf, Paul R. Elements of Photogrammetry, McGraw Hill Book Company, New York. .COPYRGT.1974, p. 309.
Lindqvist Berit
Welander Ulf
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