Research On The Model Of The Digital Watermarking For Vector Geo-spatial Data Based On DFT

Vector geospatial data is a national geospatial data infrastructure and the support of Earth science research results, it occupies a very important position in the national economy, national defense building, its security relates to science and technology cooperation, intellectual property rights, national security and so on. Traditional encryption technology can no longer meet the vector geospatial data security needs; a reliable technology is needed ugently to protect the vector geospatial data security. Digital watermark is becoming a cutting-edge technology of information security with the development of digital process. The Research of vector geospatial data digital watermarking technology used to protect the vector geospatial data security is extremely important theoretical and applied value.Based on the theory of discrete Fourier transform (DFT) and the characteristic of vector geospatial data for digital watermarking, the study and practice of theories, models and applications about DFT-based vector geospatial data digital watermarking is carried out in-depth,The issues in this dissertation are as the following:1. The background and current research of digital watermarking for vector geospatial data at home and abroad are analyzed; the concept, classification, algorithms, applications and attacks of digital watermarking are sumarrized. By analyzing the advantages of DFT in digital watermarking for the vector geospatial data, the content of the research are brought forward.2. A digital watermarking model for the vector geospatial data DFT-based amplitude is designed. After analyzing digital watermarking generating, the DFT of the vector geospatial data, embedding and extracting of digital watermarking, the availability, imperceptibility, and robustness of the model are confirmed by experiment.3. A digital watermarking model for vector geo-spatial data DFT-based phase is designed. This model is contrasted with the model of DFT amplitude according to the embedding, extracting of digital watermarking, the availability, imperceptibility, and robustness of the carrier data with embedded watermarking. Virtues and defects of two methods are pointed out.4. A combined digital watermarking model for vector geospatial data DFT-based is designed. In this model, the digital watermarking is embed in the both amplitude and phase of DFT, so it makes up the defeats of the independent DFT phase model and DFT amplitude model , the capacity of digital watermarking is high, so the model can resist more kinds of attacks.5. The autocorrelation detection is used to assist judge the result of exacted watermarking, make sure the result is objective; moreover, the detection method can make up the limitation of the models. 6. The carrier data type are studied by contrast, The experiment shows that the result of floating vector geo-spatial data is better than integer data by the model DFT-based phase and the result of the model DFT-based amplitude has few differences comparatively. The extracted result of the combined model is better than that of integer type.7. A blind detection model of the digital watermarking of vector geo-spatial data DFT-based is put forward, its understanding is from the quantization of mean value, the parameter is variable when the watermark is embedded in the amplitude of DFT, Experiments show that the model has the good detecting blind characteristics, better able to extract watermark information8. An experiment system for the digital watermarking of DFT-based vector geospatial data is developed.The system design and main functions are discussed.At last, research work is summarized and the potential research topics are discussed.