An Ellipse Conformation Deviation Estimation Method Based on Tangent Method

Abstract

The invention discloses an ellipse imaging deviation estimation method based on a tangent method. The method comprises the following steps: S101) constructing a common vertical plane and a rotation axis of a circle plane and an image plane; S102) obtaining two limit rotation angles of the common vertical plane around the rotation axis and two points on corresponding circles; and S103) calculating two tangency points of an ellipse according to the two points on the corresponding circles, the middle point between the two tangency points being the center of the ellipse, and calculating difference of projection of the ellipse center and the circle center on the image plane, the difference being ellipse imaging deviation. The method has the following advantages: 1) only a world coordinate system and a camera coordinate system are used, thereby preventing coordinate transformation among a plurality of coordinate system, and improving simplicity and precision of the method; and 2) calculation speed and precision depend on extremum calculation speed and accuracy of a rotation angle function, so that the method can meet different precision and speed requirements by adjusting function extremum calculation modes according to different actual application occasions.

Description

technical field [0001] The invention relates to the field of computer vision, in particular to a method for estimating ellipse conformation deviation based on a tangent method. Background technique [0002] After perspective projection, the circle is projected as an ellipse when the imaging plane is not parallel to the circle plane. However, the center of the projected ellipse is not the projection of the center of the circle on the image plane. The deviation between the two is called the ellipse conformation deviation. Because circular marks are often used in camera calibration, and the existing mark point recognition algorithms often use the center of the ellipse as the center of the circle for calculation. When performing high-precision optical measurement, the error introduced by the approximation process cannot be ignored. The literature "On the accuracy of videometry" (Lenz R and Fritsch D. International Archives of Photogrammetry and Remote Sensing, vol. 27 (B5), pp....

AI Technical Summary

Problems solved by technology

Because circular marks are often used in camera calibration, and the existing mark point recognition algorithms often use the center of the ellipse as the center of the circle for calculation. When performing high-precision optical measurement, the error introduced by the approximation process cannot be ignored

The literature "On the accuracy of videometry" (Lenz R and Fritsch D. International Archives of Photogrammetry and Remote Sensing, vol. 27 (B5), pp. 334-345, 1984.) first proposed that when the size of the circular feature is larger, the same as When the camera distance is too short, the eccentricity error of the ellipse will affect the accuracy of the measurement

The document "Systematic Geometric Image Measurement Errors of Circular Object Targets: Mathematical Formulation and Correction" (Ahn S J, Warnecke H J, Kotowski R. Photogrammetric Record, vol.16(93), pp.485-502, 1999.) proposed an elliptical conformation The algebraic calculation method of the deviation, but its method limits the position of the circular feature, and introduces multiple intermediate coordinate systems, and the value of the eccentricity error is given as an approximate result

This method has shortcomings in terms of simplicity, versatility and accuracy

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