Vector geospatial data digital watermarking method based on angle difference

The invention discloses a vector geospatial data digital watermarking method based on an angle difference, comprising the following steps: establishing watermark carrier models based on an angle difference by using maps as objects; selecting all curves in each map object by using the map objects as units, and defining identifications (IDs) of all the curves based on a curve feature length ratio; modulating watermark information into the watermark carrier model of each map object based on a quantization index watermark model and the IDs of all the curves; extracting the watermark information; and verifying the watermark information. The watermark information is modulated into the watermark carrier model of each map object based on the angle difference by using the quantization index modulation idea, and the intensity of the watermark information is embedded into a plurality of feature points constituting the angle, so that the invisibility of the watermark is effectively improved and the high fidelity of data is achieved without reducing the algorithm robustness.