A Fragile Watermarking Scheme for Vector Map Data Using Geographic Graticule Block-Wise Method

To solve the problem of vector map data integrity authentication,a fragile watermarking scheme using geographic graticule block-wise method is proposed.Initially,the whole vector map is divided into non-overlapping data subblocks by means of geographic graticule according to certain longitude difference and latitude difference.Then vertices in each subblock are sorted,and fragile watermarking is generated by utilizing the coordinate information before the embedding place.Finally,a vertice anti-overflow strategy is adopted to embed the authentication information through modifying the embedding digits of coordinates.Watermarking detection corresponds to the embedding procedure and does not require the participation of original vector map data.During the data authentication process,whether the map data has been tampered could be determined by comparing the consistency of the extracted watermarking with the generated watermarking.A road-linear data with a scale of 1:1 000 000 was adopted to evaluate the performance of the proposed scheme.Experimental results show that the proposed fragile watermarking scheme has satisfactory stability,imperceptibility and tamper localization ability.Therefore,the scheme is capable of authenticating the integrity of vector map data accurately.