The circle center location technique which based on imaging sensor is applied to various non-contact measuring systems

yet the requirement of the environment measuring is very strict.To enhance the adaptability of center location technique

an improvement program is proposed which is practical in dealing with the key technologies in measuring process such as anti-jamming

edge examination

center point fitting

etc.It comprehensively uses the methods of time recursive filtering

depth first search algorithm and iterative least square method.The improved measuring system has good stability and adaptability

and has been used successfully in the monitoring system for deformation of subway tunnel.