Digital photogrammetry based automatic measurement of sandstone roof of a mine |
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| Authors: | Rajendra Singh D P Chapman K B Atkinson |
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| Institution: | 1. CMRI, Dhanbad, India
2. University College London, UK
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| Abstract: | Automatic close range photogrammetric measurements are of immense importance for a hazardous industry like mining. Unfortunately, available stereomatching techniques fail for high resolution close range images due to the large variation of object depth. In this paper a diffraction grating based laser dot-matrix projector along with a CCD camera is used for automatic close range measurement of a textureless and featureless object like massive sand stone strata. Targeting of object’s surface with large number of laser dots simultaneously solved two major problems: identification of conjugate points and precise image co-ordinate measurement. Least squares based template matching is used for centroid location of images of laser dots which provided 0.03 (mean) pixels accuracy. Using analytical techniques, camera model of the projector was developed by placing it rigidly on the teleseope of a geodimeter Bundle adjustment procedure is adopted for accurate estimation of interior orientation parameters of the projector which resulted precise co-ordinates of the object space during a test scan by the developed system. |
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