In large scale measurement

digital image processing technique plays an essential role.And the precision of center extraction is one of the core factors that impact digital image processing.The common methods are traditional centroid method

gray threshold centroid method

square weighting centroid method and gauss curve fitting centroid method.For that the results of these extraction methods at different distances are different

the characters of these four methods are compared both through theoretical analysis and simulation experiment.The results show that Gauss curve fitting centroid method is more suitable for pictures taken from longer distance

while the other three methods are more suitable for photos taken from shorter distance.