High Precision Monocular Plane Measurement for Large Field of View

Abstract

In order to obtain high precision in wide-area monocular plane measurement system, a target should be large enough to cover the whole field of view (FOV). For cameras with large FOV, using a small target will seriously reduce the precision of calibration. However, using a large target causes many difficulties in making, carrying and employing the large target. In order to solve this problem, a calibration method for cameras with a large field of view(FOV) by using a fictional large plane target(FLPT) is proposed in this paper, in which the FLPT consists of multiple small targets (MST) which are placed in the measurement plane. First, get a series of images when small target are in different positions of the measuring plane. Secondly, based on refer small target, the fictional small target of each image is obtained by rotation and translation, the FLPT is built by fictional small target. Finally, intrinsic and extrinsic parameters of the camera are calculated by using the FLPT, calculate the homography matrix, to achieve a large field of view plane measurement. The experimental results show that the error of measurement and positioning is lower than 0.3% in the trapezoidal measurement field with a upper line of 1400mm, lower line of 2200mm and height of 1600mm.