Dual Perspective Imaging Measurement By No-reference Distance And Space Control Point

At present,single camera vertical target plate imaging measurement system is used for static measurement of laser irradiation accuracy.The system uses visible light camera which is sensitive to near infrared to photograph target plate and laser spot at the same time,which has the problem of low imaging quality,however,the dynamic measurement of illumination accuracy puts higher requirements on image quality,and the problem of large angle perspective error can also be produced by moving target,it is still impossible to solve this problem by using single camera measurement system.Therefore,a dual perspective imaging measurement technique without reference distance,spatial control point,simultaneous Imaging of visible Light camera and Infrared camera is proposed in this paper.(1)Design a measurement system of a dual perspective imaging.The laser illuminator irradiates the target plate moving in a straight line on the target track;The dual camera system installed on the turntable is used to collect the target plate image and the laser spot image respectively.The method proposed in this paper is used to correct the perspective error of the image,locate the feature target and calculate the illumination accuracy.(2)Correct the perspective error of the collected image.Indoors,calculate the coordinate transformation matrix by using the coordinate system relationship between the visible light camera and the infrared light camera;Outdoors,adopt the control point transformation method,calculate the perspective error correction matrix for visible-light images by positioning the cooperation target,and the perspective error correction matrix of infrared image is obtained by combining the two methods.Thus,the perspective error correction of visible and infrared images is realized,that is dual perspective imaging measurement technology.(3)Detect and locate feature targets.Firstly,the projection method is used to calculate the cross center of the target;then,the Gaussian surface fitting is combined with the local gray center of gravity to accurately locate the laser spot center;finally,the offset from the center of the laser spot to the cross center of the target plate is calculated,which is the illumination accuracy to be measured.The experimental results show: In indoor registration experiment,the re-projection error of coordinate transformation is less than 0.5 pixels,in the field test,the dual perspective imaging measurement technology can effectively remove the perspective error of the image and accurately locate the feature target;the average error of static detection is 3.88 mm and the relative error is 0.53%;the average error of dynamic measurement is 5.93 mm,and the relative error is 0.81%,which meets the actual measurement requirements,it can accurately measure the laser irradiation accuracy,and it has the characteristics of fast measuring speed,simple structure and convenient to carry out the experiment.