Robust Watermarking Scheme for Vector Geographic Data Based on the Ratio Invariance of DWT–CSVD Coefficients

Traditional frequency-domain watermarking algorithms for vector geographic data suffer from disadvantages such as the random watermark embedding position, unpredictable strength, and difficulty in resisting multiple attacks at same time. To address these problems, we propose a novel algorithm based on geometric invariance of ratios discrete wavelet transform (DWT) complex singular value decomposition (CSVD) coefficients, which embeds information new domain. The proposed scheme first extracts feature points original using Douglas–Peucker algorithm, then constructs sequence set. two-level DWT is performed to obtain low frequency coefficients (L2) high (H2). On this premise, CSVD utilized calculate values L2 H2, ratio H2 acquired During process, created by fusion index bits improve recognition information, decimal part different positions altered control strength. experimental results show that not only robust common geometric, cropping, simplification, coordinate point editing, but also can extract images with probability under attacks.