[01] Sun Yu, Dept. of Computer Science & Technology, Xi’an University of Science and Technology, Xi’an, China.

Aiming at enhancing the spatial coordinates precision solved from 2D images, a new method for calculation of 3D model coordinate transformation between image side and object side space is proposed based on projective geometry. CCD camera imaging geometric principle is analyzed based on perspective transformation and cross-ratio invariant properties. Imaging geometric model based on linear feature is established using the relationship of parallel, perpendicular and intersecting between straight lines. With acquired photographs and camera parameters, the shape and size of the corresponding scene space is deduced and proved on the basis of the cross ratio invariability of collinear points with perspective projection. The coordinate transformation between image side and object side space of the 3D model is calculated. And perspective correspondence from image side to object side space is built. Experimental results prove that calculation accuracy of the spatial points coordinates can be enhanced using image geometric information. The method can be applied to enhance the precision of image feature extraction and location of geometric features such as circle, and to increase the measurement precisiong of the photogrammetry system and 3-D coordinate reconstruction.

CCD Camera, Projective Geometry, Perspective Transformation, Cross Ratio, Imaging Model

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