Abstract: Aiming at the problem of low measurement accuracy caused by the poor roundness of the traditional type of retro-reflective target,a new type of retro-reflective target is designed,that is,the round hole mold slice with small roundness error is covered on the glass bead reflective film,and the new type of retro-reflective target is tested to reduce the roundness error of the traditional type retro-reflective target by an average of 0.03 mm.The image point center positioning model of the new retro-reflective target is established,the influence of the thickness of the mold slice on the center positioning accuracy of the image point is analyzed,and the accuracy of the new retro-reflective target is evaluated from the aspects of internal accord accuracy and external accord accuracy.The experimental results show that the repeatability measurement accuracy and standard length measurement accuracy of the new retro-reflective target are improved by 25.0% and 28.1% respectively compared with the traditional retro-reflective target,the high measurement performance of the new return light reflection mark is fully proved.

Key words: Industrial photogrammetry, Retro-reflective targets, Targets roundness, Internal accord accuracy, External accord accuracy