There are a large number of Earthen sites which have great historical and scientific value

and are easily affected by cracks

but the exsiting calculation methods of crack width of the Earthen sites are mechanical measurements

which takes much time

energy and cost

even makes damage to the Earthen sites.Therefore

propose a calculation method of crack width of the Earthen sites via directions of the centerlines.Firstly

this method carry out de-noising and morphological processing on crack image.Then the centerlines of cracks are obtained by thinning.Finally

based on direction of each point in centerline

calculate the distances between the intersection points of its normal and left / right boundaries of the crack

and these distances are used as the crack widths.Experimental results demonstrate that this calculation method has high accuracy and commonality.