Geometric attack resistant vector geographic point data lossless watermark generation and extraction method

Abstract

The invention discloses a geometric attack-resistant vector geographic point data lossless watermark generation and extraction method, which comprises the following steps of: before watermark embedding, firstly generating Thiessen polygons of vector point data, and enabling each point element to correspond to a unique Thiessen polygon; secondly, according to the relationship between the perimeter sizes of the Thiessen polygons of the adjacent point elements, determining the storage directions of the points, and normalizing the sum of the perimeter sizes of the Thiessen polygons of the adjacent points to establish a Hash mapping relationship with the watermark information; and finally, rearranging the storage sequence of the point elements to embed the watermark. And when the watermark is detected, generating a Thiessen polygon of vector point data to be detected, and extracting the watermark according to the storage direction of adjacent point elements. Experimental results show that the algorithm has good robustness on translation, zooming and rotation, lossless embedding of the watermark is realized due to the fact that coordinate values are not changed, the requirement of high-precision data is met, and the algorithm has good practicability.

Description

Technical Field

[0001] This invention relates to the field of vector geographic data copyright protection technology, specifically to a method for generating and extracting lossless watermarks from vector geographic point data that resists geometric attacks. Background Technology

[0002] Vector geographic data, as crucial data in surveying, remote sensing, and GIS, is an indispensable strategic resource for national economic and defense development. With the increasing demand for sharing geographic data, illegal use and infringement of vector geographic data occur frequently, thus urgently requiring effective technical means for copyright protection and source tracing.

[0003] Currently, there are many research results both domestically and internationally on using digital watermarking technology to protect the security of vector geographic data. Based on different embedding domains, watermarking algorithms can be divided into spatial domain, transform domain, and geometric domain algorithms. Spatial domain watermarking algorithms directly embed watermark information into the spatial coordinates of the data, exhibiting strong resistance to point addition / deletion and pruning attacks. Transform domain watermarking algorithms embed watermark information into the coefficients of the transform domain, offering some resistance to noise, translation, and rotation attacks. Geometric domain watermarking algorithms embed the watermark into the geometric features of the geographic data, demonstrating good robustness against geometric attacks.

[0004] However, geometric attacks are a common attack method for vector geographic data. Many scholars have proposed different algorithms, all of which can resist geometric attacks to some extent, but all suffer a loss of spatial data accuracy. Existing technologies include a lossless watermarking algorithm that reorders the storage sequence. This algorithm embeds the watermark by changing the storage order of adjacent line or polygon features. Since the watermark embedding process does not change the coordinate values, it achieves lossless embedding of watermark information. However, the storage direction in this algorithm is defined using the number of vertices in adjacent line or polygon data. Therefore, this algorithm is only applicable to line and polygon data, and cannot be used for point data. Based on the above problems, this invention proposes a lossless watermarking algorithm suitable for vector point data. It generates Thiessen polygons from the vector point data to be watermarked, determines the storage direction based on the perimeter relationship of the Thiessen polygons, and embeds the watermark information by rearranging the storage order. This not only resists arbitrary geometric transformations but also achieves lossless embedding of watermark information. Summary of the Invention

[0005] This application provides a method for generating and extracting lossless watermarks from vector geographic point data that is resistant to geometric attacks, in order to solve the problems of spatial data accuracy loss, applicability only to line and polygon data, and inability to use point data in existing technologies.

[0006] According to a first aspect, one embodiment provides a lossless watermarking method for vector geographic point data resistant to geometric attacks, the method comprising:

[0007] Obtain the original binary watermark image, scramble the watermark image, and then convert it into a one-dimensional watermark sequence;

[0008] Acquire vector geographic point data and construct unique Thiessen polygons for all point features;

[0009] Based on the comparison of the perimeters of the Thiessen polygons of two adjacent point pairs, the storage direction value of the two adjacent point pairs is determined.

[0010] Obtain the normalized value of the sum of the perimeters of the Thiessen polygons of two adjacent point pairs, and establish a hash mapping relationship between the normalized value and the watermark bits in the one-dimensional watermark sequence to determine the watermark embedding position.

[0011] Based on whether the storage direction value and the corresponding watermark bit value of two adjacent point pairs are consistent, the storage order of the two adjacent point pairs is rearranged, and finally watermarked vector geographic point data is generated.

[0012] Further, the original binary watermark image is obtained, and after scrambling the watermark image, it is converted into a one-dimensional watermark sequence, specifically including:

[0013] The Arnold transform is applied to scramble the watermark image and convert it into a one-dimensional watermark sequence. ,in It is the length of the watermark. It is the value of a single watermark bit, and i is the position index of the one-dimensional sequence.

[0014] Furthermore, based on the comparison of the perimeters of the Thiessen polygons of two adjacent point pairs, the storage direction of the points is determined, specifically including:

[0015] If the perimeter of the Thiessen polygon at the previous point is greater than the perimeter of the Thiessen polygon at the next point, then the storage direction value is 1; otherwise, the storage direction value is 0.

[0016] Furthermore, the sum of the perimeters of the Thiessen polygons of two adjacent point pairs is obtained, normalized, and a hash mapping relationship is established between the normalized value and the watermark bits in the one-dimensional watermark sequence to determine the watermark embedding position. Specifically, this includes:

[0017] The sum of the perimeters of the Thiessen polygons for any two adjacent point pairs is min-max normalized, and the normalized value is then amplified. The hash mapping relationship is established between the watermark bits in the one-dimensional watermark sequence and the watermark position to determine the watermark embedding position. The value is determined by the length of the watermark;

[0018] The mapping relationship is Decision, among which Amplify the normalized value times, This represents the length of the watermark.

[0019] Furthermore, based on whether the storage direction values ​​and corresponding watermark bit values ​​of two adjacent point pairs are consistent, the storage order of the two adjacent point pairs is rearranged to finally generate watermarked vector geographic point data, specifically including:

[0020] If the storage direction value of two adjacent point pairs is consistent with the value of the watermark bit mapped by the two adjacent point pairs, the storage order of the adjacent point pairs will not be changed; otherwise, the storage order of the adjacent point pairs will be changed.

[0021] According to a second aspect, one embodiment provides a method for lossless watermark extraction of vector geographic point data resistant to geometric attacks, the method comprising:

[0022] Obtain watermarked vector geographic point data and construct unique Thiessen polygons for all point features;

[0023] Obtain the normalized value of the sum of the perimeters of the Thiessen polygons of two adjacent point pairs, and establish a hash mapping relationship between the normalized value and the watermark bits in the one-dimensional watermark sequence to determine the watermark embedding position.

[0024] The values ​​of individual watermark bits are extracted sequentially based on the watermark embedding position. In the case where multiple adjacent point pairs are mapped to the same watermark bit, a voting principle is used to determine the final watermark bit value, resulting in a one-dimensional watermark sequence.

[0025] The extracted one-dimensional watermark sequence is up-dimension processed and de-scrambled to obtain the final binarized watermark image.

[0026] Furthermore, the sum of the perimeters of the Thiessen polygons of two adjacent point pairs is obtained, normalized, and a hash mapping relationship is established between the normalized value and the watermark bits in the one-dimensional watermark sequence to determine the watermark embedding position. Specifically, this includes:

[0027] The sum of the perimeters of the Thiessen polygons for any two adjacent point pairs is min-max normalized, and the normalized value is then amplified. The hash mapping relationship is established between the watermark bits in the one-dimensional watermark sequence and the watermark position to determine the watermark embedding position. The value is determined by the length of the watermark.

[0028] Furthermore, for cases where multiple adjacent point pairs map to the same watermark bit, a voting principle is used to determine the final watermark bit value, resulting in a one-dimensional watermark sequence, specifically including:

[0029] First, define a one-dimensional sequence of the same length as the embedded watermark. ,in This is the length of the watermark; The initial value for each watermark bit is 0; i is the position index of the defined one-dimensional sequence.

[0030] Watermark values ​​mapped to the same location are summed using an accumulation formula. To conduct statistics, among which It is by The rule is: if ,but ,otherwise ; This is the value extracted each time the watermark is retrieved, and it can only take the values ​​0 and 1. Depend on The assignment takes only two values: 1 and -1. If... If the value is 1, then the corresponding watermark bit is 1; otherwise, the corresponding watermark bit is 0. The calculation formula is as follows:

[0031]

[0032]

[0033] in The perimeter of the Thiessen polygon generated for the first point feature in a pair of adjacent points. The perimeter of the Thiessen polygon generated for the second point feature in a pair of adjacent points; It stores the direction value for two adjacent point pairs; The final value of the watermark bit can only be 0 or 1; i is the position index of the defined one-dimensional sequence.

[0034] According to a third aspect, one embodiment provides a lossless watermark generation system for vector geographic point data resistant to geometric attacks, the system comprising:

[0035] The one-dimensional sequence generation module is used to obtain the original binary watermark image and convert it into a one-dimensional watermark sequence after scrambling the watermark image.

[0036] The Thiessen polygon generation module is used to acquire vector geographic point data and construct unique Thiessen polygons for all point features;

[0037] The storage direction determination module is used to determine the storage direction value of two adjacent point pairs based on the comparison results of the perimeters of the Thiessen polygons of the two adjacent point pairs.

[0038] The watermark mapping module is used to obtain the normalized value of the sum of the perimeters of the Thiessen polygons of two adjacent point pairs, and to establish a hash mapping relationship between the normalized value and the watermark bits in the one-dimensional watermark sequence to determine the watermark embedding position.

[0039] The order reordering module is used to rearrange the storage order of two adjacent point pairs based on whether the storage direction value and the corresponding watermark bit value are consistent, and finally generate watermarked vector geographic point data.

[0040] According to the fourth aspect, one embodiment provides a lossless watermark extraction system for vector geographic point data resistant to geometric attacks, the system comprising:

[0041] The Thiessen polygon generation module is used to acquire watermarked vector geographic point data and construct unique Thiessen polygons for all point features.

[0042] The watermark mapping module is used to obtain the normalized value of the sum of the perimeters of the Thiessen polygons of two adjacent point pairs, and to establish a hash mapping relationship between the normalized value and the watermark bits in the one-dimensional watermark sequence to determine the watermark embedding position.

[0043] The one-dimensional sequence generation module is used to extract the value of a single watermark bit in sequence according to the watermark embedding position. When multiple adjacent point pairs are mapped to the same watermark bit, a voting principle is used to determine the final watermark bit value to obtain a one-dimensional watermark sequence.

[0044] The watermark acquisition module is used to perform dimensionality upscaling and descrambling on the extracted one-dimensional watermark sequence to obtain the final binarized watermark image.

[0045] This application, based on the invariant characteristics of vector geographic data, provides a lossless watermark generation and extraction method for vector geographic point data that is resistant to geometric attacks. First, it utilizes the stability property of Thiessen polygons in the point data to construct the relationship between the watermark information and the data, effectively resisting arbitrary geometric attacks. Second, it rearranges the storage order of the point features to embed the watermark information, achieving lossless embedding. Simulation experiments demonstrate that the algorithm exhibits excellent robustness against geometric attacks, and the lossless embedding of watermark information also addresses the need for high-precision data. Attached Figure Description

[0046] Figure 1 A flowchart illustrating a lossless watermarking method for vector geographic point data resistant to geometric attacks, provided as an embodiment of the present invention;

[0047] Figure 2 A flowchart illustrating the watermark embedding process in a lossless watermarking method for vector geographic point data resistant to geometric attacks, provided as an embodiment of the present invention.

[0048] Figure 3 A diagram showing the change in storage order before and after watermarking in a lossless watermarking method for vector geographic point data resistant to geometric attacks, provided as an embodiment of the present invention;

[0049] Figure 4A flowchart of watermark extraction in a lossless watermarking method for vector geographic point data resistant to geometric attacks provided in an embodiment of the present invention;

[0050] Figure 5 Experimental data diagram of a lossless watermarking method for vector geographic point data resistant to geometric attacks provided in an embodiment of the present invention;

[0051] Figure 6 The watermark image is provided in a lossless watermarking method for vector geographic point data that resists geometric attacks, as an embodiment of the present invention.

[0052] Figure 7 A visual comparison chart of a lossless watermarking method for vector geographic point data resistant to geometric attacks provided in an embodiment of the present invention;

[0053] Figure 8 An enlarged experimental image of a lossless watermarking method for vector geographic point data resistant to geometric attacks provided in an embodiment of the present invention;

[0054] Figure 9 A scaled-down experimental image is provided in an embodiment of the present invention for a lossless watermarking method for vector geographic point data that resists geometric attacks;

[0055] Figure 10 This is a translational experimental diagram in a lossless watermarking method for vector geographic point data that resists geometric attacks, provided as an embodiment of the present invention.

[0056] Figure 11 This is a rotating experimental diagram in a lossless watermarking method for vector geographic point data that resists geometric attacks, provided as an embodiment of the present invention. Detailed Implementation

[0057] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings. Similar elements in different embodiments are referred to by associated similar element reference numerals. In the following embodiments, many details are described to facilitate a better understanding of this application. However, those skilled in the art will readily recognize that some features may be omitted in different situations, or may be replaced by other elements, materials, or methods. In some cases, certain operations related to this application are not shown or described in the specification. This is to avoid obscuring the core parts of this application with excessive description. For those skilled in the art, detailed description of these related operations is not necessary; they can fully understand the related operations based on the description in the specification and general technical knowledge in the art.

[0058] Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various embodiments. At the same time, the steps or actions in the method description can be rearranged or adjusted in a manner obvious to those skilled in the art. Therefore, the various orders in the specification and drawings are only for the clear description of a particular embodiment and do not imply a necessary order, unless otherwise stated that a particular order must be followed.

[0059] The first embodiment of this invention provides a method for generating lossless watermarks for vector geographic point data that is resistant to geometric attacks. The following is in conjunction with... Figure 1 Please provide a detailed explanation.

[0060] like Figure 1 As shown, in step S110, the original binary watermark image is obtained, and after scrambling the watermark image, it is converted into a one-dimensional watermark sequence.

[0061] Specifically, in this embodiment, the Arnold transform is used to scramble the watermark image and convert it into a one-dimensional watermark sequence. ,in It is the length of the watermark. It is the value of a single watermark bit, and i is the position index of the one-dimensional sequence.

[0062] like Figure 1 As shown, in step S120, vector geographic point data is acquired, and a unique Thiessen polygon is constructed for all point features.

[0063] like Figure 1 As shown, in step S130, the storage direction value of the two adjacent point pairs is determined based on the comparison result of the size of the perimeter of the Thiessen polygon of the two adjacent point pairs.

[0064] Specifically, if the perimeter of the Thiessen polygon at the previous point is greater than the perimeter of the Thiessen polygon at the next point, the storage direction value is 1; otherwise, the storage direction value is 0.

[0065] like Figure 1 As shown, in step S140, the sum of the perimeters of the Thiessen polygons of two adjacent point pairs is obtained and normalized. The normalized value is then used to establish a hash mapping relationship with the watermark bit in the one-dimensional watermark sequence to determine the watermark embedding position.

[0066] Specifically, the sum of the perimeters of the Thiessen polygons for any two adjacent point pairs is min-max normalized, and the normalized value is then amplified. The hash mapping relationship is established between the watermark bits in the one-dimensional watermark sequence and the watermark position to determine the watermark embedding position. The value is determined by the length of the watermark;

[0067] The mapping relationship is Decision, among which Amplify the normalized value times, This represents the length of the watermark.

[0068] The normalization formula is as follows:

[0069]

[0070] In the formula The sum of the perimeters of the Thiessen polygons of adjacent point features. and Let these represent the minimum and maximum values ​​of the sum of the perimeters, respectively. It is the normalized value, and this value will be mapped to... between.

[0071] like Figure 1 As shown, in step S150, the storage order of two adjacent point pairs is rearranged according to whether the storage direction value and the corresponding watermark bit value of two adjacent point pairs are consistent, and finally watermarked vector geographic point data is generated.

[0072] Specifically, if the storage direction values ​​of two adjacent point pairs are consistent with the values ​​of the watermark bits mapped to the adjacent point pairs, then the storage order of the adjacent point pairs will not be changed; otherwise, the storage order of the adjacent point pairs will be changed. For example... Figure 3 As shown.

[0073] The second embodiment of the present invention provides a method for lossless watermark extraction and generation of vector geographic point data resistant to geometric attacks, the specific steps of which are as follows:

[0074] In step S210, watermarked vector geographic point data is obtained, and unique Thiessen polygons for all point features are constructed.

[0075] In step S220, the sum of the perimeters of the Thiessen polygons of two adjacent point pairs is obtained and normalized. The normalized value is then used to establish a hash mapping relationship with the watermark bits in the one-dimensional watermark sequence to determine the watermark embedding position.

[0076] Specifically, the sum of the perimeters of the Thiessen polygons at two adjacent points is subjected to min-max normalization, and the normalized value is then amplified. The hash mapping between the watermark and the hash value is established to determine the watermark's location. The value is consistent with the embedding.

[0077] In step S230, the values ​​of individual watermark bits are extracted sequentially according to the watermark embedding position. When multiple adjacent point pairs are mapped to the same watermark bit, the voting principle is used to determine the final watermark bit value, resulting in a one-dimensional watermark sequence.

[0078] Specifically, due to each watermark position It may be embedded multiple times, so a voting principle is used to determine the final watermark information. The method is as follows:

[0079] First, define a one-dimensional sequence of the same length as the watermark. , This represents the length of the watermark. The initial value for each watermark bit is 0, and i is the position index of the defined one-dimensional sequence.

[0080] Watermark information at the same location is accumulated using a formula. To conduct statistics It is by The rule is: if ,but ,otherwise .in This is the value extracted each time the watermark is retrieved, and this value can only be 0 or 1; Depend on The assignment is performed, and the value can only take the values ​​1 and -1. Ultimately, if... If the value is 1, the watermark information is 1; otherwise, the watermark information is 0. This can be calculated using a formula.

[0081]

[0082]

[0083] in The perimeter of the Thiessen polygon generated for the first point feature in a pair of adjacent points. The perimeter of the Thiessen polygon generated for the second point feature in a pair of adjacent points; It stores the direction value for two adjacent point pairs; The final value of the watermark bit can only be 0 or 1; i is the position index of the defined one-dimensional sequence.

[0084] Each extracted watermark is mapped to a defined one-dimensional sequence according to the mapping relationship. Each position may be mapped multiple times. Each time the same position is mapped, it is accumulated once by the above accumulation formula. The result of the accumulation is either >0 or ≤0. Finally, if >0, the value of the watermark position is 1; if ≤0, the value of the watermark position is 0.

[0085] In step S240, the extracted one-dimensional watermark sequence is up-dimension processed and de-scrambled to obtain the final binarized watermark image.

[0086] Experimental example:

[0087] To verify the algorithm's performance, a simulation experiment was conducted using Python 3.7 on a Windows 10 operating system. The experimental data included vector point data of some buildings in Mexico (Data 1), vector point data of some buildings in New Zealand (Data 2), and vector point data of various schools in some regions of China (Data 3). The basic information of the three sets of experimental data is shown in Table 1 below, and the graphs for the three sets of experimental data are as follows. Figure 5 (a), Figure 5 (b) and Figure 5 (c):

[0088] Table 1 Basic Information of Experimental Data

[0089]

[0090] This invention uses root mean square error (RMSE) to measure the impact of watermark embedding on the accuracy of vector data, as shown in the formula.

[0091]

[0092] In the formula, This indicates the number of vector point data. This indicates the absolute error between the coordinates of the original point feature and the coordinates of the watermarked point feature.

[0093] The correlation coefficient (NC) is typically used to evaluate the extracted watermark image against the original watermark image, as shown in the calculation formula.

[0094]

[0095] In the formula, Indicates the size of the watermark image; This represents the original watermark information; This indicates the extracted watermark information; This represents the XOR NOT operation.

[0096] (1) Error and Invisibility Analysis

[0097] The data in the table comes from three datasets in the experiment. As can be seen from the table, the RMSE value is 0 for all datasets, meaning that the coordinates of all data points remained unchanged after watermark embedding, achieving lossless watermark embedding. Therefore, even after watermark embedding, the algorithm of this invention does not affect the usability of the data at all. The error results are shown in Table 2.

[0098] Table 2. Statistics on Coordinate Value Changes

[0099]

[0100] By visually overlaying and comparing the data before and after watermark embedding, and zooming in on specific areas, it is evident that the data coordinates remain unchanged, thus exhibiting excellent invisibility. Figure 7 As shown.

[0101] (2) Robustness analysis

[0102] To verify the algorithm's resistance to geometric attacks, four sets of experiments were conducted to test geometric attacks. Figure 8 It is a scaling-down experiment, from a reduction of 0.1 times to a reduction of 1.0 times. Figure 9 It is a magnification experiment, from magnification of 1.0 times to magnification of 10 times. Figure 10 It is a translation experiment. The translation experiment involves taking the difference between the maximum and minimum x-coordinates and multiplying it by a translation transformation coefficient to perform the translation. The translation of the y-coordinate follows the same rules as the x-coordinate. Figure 11 It is a rotation experiment, from rotating 30° to rotating 360°.

[0103] Experiments show that the algorithm of this invention can completely extract the watermark information after arbitrary scaling, translation, and rotation, and the NC value is always 1. Therefore, the algorithm of this invention has good robustness against arbitrary geometric attacks.

[0104] The comparative experiments selected robust experimental methods. Method 1 is a spatial domain algorithm resistant to geometric attacks, while Method 2 is a lossless watermarking algorithm that rearranges the storage order. The results of the comparative experiments are shown in Table 3-4 below:

[0105] Table 3 Robustness assessment of translation and scaling attacks

[0106]

[0107] Table 4 Robustness Assessment of Spin Attack

[0108]

[0109] The experimental results in Tables 3 and 4 show that the algorithm offers some resistance to geometric attacks, but not to rotational attacks, requiring prior knowledge of the rotation parameters, thus limiting its effectiveness. For vector point data, although the idea of ​​rearranging the storage order to embed the watermark is also used, the storage direction is defined by the number of vertices of adjacent line or polygon features. Point data does not have this characteristic, therefore, watermark information cannot be extracted from vector point data at all. This invention uses the invariance and uniqueness of the Thiessen polygons of adjacent point features to embed the watermark, which can completely resist any geometric attack, thus exhibiting good robustness against geometric attacks.

[0110] Corresponding to the aforementioned method for generating lossless watermarks of vector geographic point data resistant to geometric attacks, this invention also discloses a system for generating lossless watermarks of vector geographic point data resistant to geometric attacks, which specifically includes:

[0111] The one-dimensional sequence generation module is used to obtain the original binary watermark image and convert it into a one-dimensional watermark sequence after scrambling the watermark image.

[0112] The Thiessen polygon generation module is used to acquire vector geographic point data and construct unique Thiessen polygons for all point features;

[0113] The storage direction determination module is used to determine the storage direction value of two adjacent point pairs based on the comparison results of the perimeters of the Thiessen polygons of the two adjacent point pairs.

[0114] The watermark mapping module is used to obtain the normalized value of the sum of the perimeters of the Thiessen polygons of two adjacent point pairs, and to establish a hash mapping relationship between the normalized value and the watermark bits in the one-dimensional watermark sequence to determine the watermark embedding position.

[0115] The order reordering module is used to rearrange the storage order of two adjacent point pairs based on whether the storage direction value and the corresponding watermark bit value are consistent, and finally generate watermarked vector geographic point data.

[0116] It should be noted that for a detailed description of the lossless watermarking system for vector geographic point data resistant to geometric attacks provided in the embodiments of the present invention, please refer to the relevant description of the lossless watermarking method for vector geographic point data resistant to geometric attacks provided in the embodiments of this application, which will not be repeated here.

[0117] Corresponding to the aforementioned method for extracting lossless watermarks from vector geographic point data resistant to geometric attacks, this invention also discloses a system for extracting lossless watermarks from vector geographic point data resistant to geometric attacks, which specifically includes:

[0118] The Thiessen polygon generation module is used to acquire watermarked vector geographic point data and construct unique Thiessen polygons for all point features.

[0119] The watermark mapping module is used to obtain the normalized value of the sum of the perimeters of the Thiessen polygons of two adjacent point pairs, and to establish a hash mapping relationship between the normalized value and the watermark bits in the one-dimensional watermark sequence to determine the watermark embedding position.

[0120] The one-dimensional sequence generation module is used to extract the value of a single watermark bit in sequence according to the watermark embedding position. When multiple adjacent point pairs are mapped to the same watermark bit, a voting principle is used to determine the final watermark bit value to obtain a one-dimensional watermark sequence.

[0121] The watermark acquisition module is used to perform dimensionality upscaling and descrambling on the extracted one-dimensional watermark sequence to obtain the final binarized watermark image.

[0122] It should be noted that for a detailed description of the non-destructive watermark extraction system for vector geographic point data resistant to geometric attacks provided in the embodiments of the present invention, please refer to the relevant description of the non-destructive watermark extraction method for vector geographic point data resistant to geometric attacks provided in the embodiments of this application, which will not be repeated here.

[0123] In addition, embodiments of the present invention also provide an electronic device, the device comprising: a processor and a memory; the memory being used to store one or more program instructions; the processor being used to execute one or more program instructions to perform the steps of a geometrically resistant vector geographic point data lossless watermarking method as described in any of the preceding embodiments.

[0124] It should be noted that for a detailed description of an electronic device provided in the embodiments of the present invention, please refer to the relevant description of a lossless watermarking method for vector geographic point data resistant to geometric attacks provided in the embodiments of this application, which will not be repeated here.

[0125] In addition, embodiments of the present invention also provide a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of a lossless watermarking method for vector geographic point data resistant to geometric attacks as described in any of the preceding embodiments.

[0126] It should be noted that for a detailed description of the computer-readable storage medium provided in the embodiments of the present invention, please refer to the relevant description of the lossless watermarking method for vector geographic point data resistant to geometric attacks provided in the embodiments of this application, which will not be repeated here.

[0127] Those skilled in the art will understand that all or part of the functions of the various methods in the above embodiments can be implemented by hardware or by computer programs. When all or part of the functions in the above embodiments are implemented by computer programs, the program can be stored in a computer-readable storage medium, which may include: read-only memory, random access memory, disk, optical disk, hard disk, etc., and the program is executed by a computer to achieve the above functions. For example, the program can be stored in the memory of a device, and when the program in the memory is executed by the processor, all or part of the above functions can be achieved. In addition, when all or part of the functions in the above embodiments are implemented by computer programs, the program can also be stored in a server, another computer, disk, optical disk, flash drive, or external hard drive, etc., and can be downloaded or copied to the memory of a local device, or the system of the local device can be updated. When the program in the memory is executed by the processor, all or part of the functions in the above embodiments can be achieved.

[0128] The above examples illustrate the present invention only to aid in understanding it and are not intended to limit the scope of the invention. Those skilled in the art can make various simple deductions, modifications, or substitutions based on the principles of this invention.

Claims

1. A method for generating lossless watermarks from vector geographic point data resistant to geometric attacks, characterized in that, The method includes: Obtain the original binary watermark image, scramble the watermark image, and then convert it into a one-dimensional watermark sequence; Acquire vector geographic point data and construct unique Thiessen polygons for all point features; Based on the comparison of the perimeters of the Thiessen polygons of two adjacent point pairs, the storage direction value of the two adjacent point pairs is determined. Obtain the normalized value of the sum of the perimeters of the Thiessen polygons of two adjacent point pairs, and establish a hash mapping relationship between the normalized value and the watermark bits in the one-dimensional watermark sequence to determine the watermark embedding position. Based on whether the storage direction value and the corresponding watermark bit value of two adjacent point pairs are consistent, the storage order of the two adjacent point pairs is rearranged, and finally watermarked vector geographic point data is generated.

2. The method for generating lossless watermarks for vector geographic point data resistant to geometric attacks as described in claim 1, characterized in that, Obtain the original binary watermark image, scramble the watermark image, and then convert it into a one-dimensional watermark sequence. Specifically, this includes: The Arnold transform is applied to scramble the watermark image and convert it into a one-dimensional watermark sequence. ,in It is the length of the watermark. It is the value of a single watermark bit, and i is the position index of the one-dimensional sequence.

3. The method for generating lossless watermarks for vector geographic point data resistant to geometric attacks as described in claim 1, characterized in that, The storage direction of a point is determined based on the comparison of the perimeters of the Thiessen polygons of two adjacent point pairs. Specifically, this includes: If the perimeter of the Thiessen polygon at the previous point is greater than the perimeter of the Thiessen polygon at the next point, then the storage direction value is 1; otherwise, the storage direction value is 0.

4. The method for generating lossless watermarks for vector geographic point data resistant to geometric attacks as described in claim 1, characterized in that, Obtain the normalized sum of the perimeters of the Thiessen polygons for two adjacent point pairs, and establish a hash mapping relationship between the normalized value and the watermark bits in the one-dimensional watermark sequence to determine the watermark embedding position. Specifically, this includes: The sum of the perimeters of the Thiessen polygons for any two adjacent point pairs is min-max normalized, and the normalized value is then amplified. The hash mapping relationship is established between the watermark bits in the one-dimensional watermark sequence and the watermark position to determine the watermark embedding position. The value is determined by the length of the watermark; The mapping relationship is Decision, among which Amplify the normalized value times, This represents the length of the watermark.

5. The method for generating lossless watermarks for vector geographic point data resistant to geometric attacks as described in claim 1, characterized in that, Based on whether the storage direction values ​​and corresponding watermark bit values ​​of two adjacent point pairs are consistent, the storage order of the two adjacent point pairs is rearranged to finally generate watermarked vector geographic point data, specifically including: If the storage direction value of two adjacent point pairs is consistent with the value of the watermark bit mapped by the two adjacent point pairs, the storage order of the adjacent point pairs will not be changed; otherwise, the storage order of the adjacent point pairs will be changed.

6. A method for lossless watermark extraction from vector geographic point data resistant to geometric attacks, characterized in that, The method includes: Obtain watermarked vector geographic point data and construct unique Thiessen polygons for all point features; Obtain the normalized value of the sum of the perimeters of the Thiessen polygons of two adjacent point pairs, and establish a hash mapping relationship between the normalized value and the watermark bits in the one-dimensional watermark sequence to determine the watermark embedding position. The values ​​of individual watermark bits are extracted sequentially based on the watermark embedding position. In the case where multiple adjacent point pairs are mapped to the same watermark bit, a voting principle is used to determine the final watermark bit value, resulting in a one-dimensional watermark sequence. The extracted one-dimensional watermark sequence is up-dimension processed and de-scrambled to obtain the final binarized watermark image.

7. The method for lossless watermark extraction of vector geographic point data resistant to geometric attacks as described in claim 6, characterized in that, Obtain the normalized sum of the perimeters of the Thiessen polygons for two adjacent point pairs, and establish a hash mapping relationship between the normalized value and the watermark bits in the one-dimensional watermark sequence to determine the watermark embedding position. Specifically, this includes: The sum of the perimeters of the Thiessen polygons for any two adjacent point pairs is min-max normalized, and the normalized value is then amplified. The hash mapping relationship is established between the watermark bits in the one-dimensional watermark sequence and the watermark position to determine the watermark embedding position. The value is determined by the length of the watermark.

8. The method for lossless watermark extraction of vector geographic point data resistant to geometric attacks as described in claim 6, characterized in that, For cases where multiple adjacent point pairs map to the same watermark bit, a voting principle is used to determine the final watermark bit value, resulting in a one-dimensional watermark sequence, specifically including: First, define a one-dimensional sequence of the same length as the embedded watermark. ,in This is the length of the watermark; The initial value for each watermark bit is 0; i is the position index of the defined one-dimensional sequence. Watermark values ​​mapped to the same location are summed using an accumulation formula. To conduct statistics, among which It is by The rule is: if ,but ,otherwise ; This is the value extracted each time the watermark is retrieved, and it can only take the values ​​0 and 1. Depend on The assignment takes only two values: 1 and -1. If... If the value is 1, then the corresponding watermark bit is 1; otherwise, the corresponding watermark bit is 0. The calculation formula is as follows: in The perimeter of the Thiessen polygon generated for the first point feature in a pair of adjacent points. The perimeter of the Thiessen polygon generated for the second point feature in a pair of adjacent points; It stores the direction value for two adjacent point pairs; The final value of the watermark bit can only be 0 or 1; i is the position index of the defined one-dimensional sequence.

9. A lossless watermark generation system for vector geographic point data resistant to geometric attacks, characterized in that, The system includes: The one-dimensional sequence generation module is used to obtain the original binary watermark image and convert it into a one-dimensional watermark sequence after scrambling the watermark image. The Thiessen polygon generation module is used to acquire vector geographic point data and construct unique Thiessen polygons for all point features; The storage direction determination module is used to determine the storage direction value of two adjacent point pairs based on the comparison results of the perimeters of the Thiessen polygons of the two adjacent point pairs. The watermark mapping module is used to obtain the normalized value of the sum of the perimeters of the Thiessen polygons of two adjacent point pairs, and to establish a hash mapping relationship between the normalized value and the watermark bits in the one-dimensional watermark sequence to determine the watermark embedding position. The order reordering module is used to rearrange the storage order of two adjacent point pairs based on whether the storage direction value and the corresponding watermark bit value are consistent, and finally generate watermarked vector geographic point data.

10. A lossless watermark extraction system for vector geographic point data resistant to geometric attacks, characterized in that, The system includes: The Thiessen polygon generation module is used to acquire watermarked vector geographic point data and construct unique Thiessen polygons for all point features. The watermark mapping module is used to obtain the normalized value of the sum of the perimeters of the Thiessen polygons of two adjacent point pairs, and to establish a hash mapping relationship between the normalized value and the watermark bits in the one-dimensional watermark sequence to determine the watermark embedding position. The one-dimensional sequence generation module is used to extract the value of a single watermark bit in sequence according to the watermark embedding position. When multiple adjacent point pairs are mapped to the same watermark bit, a voting principle is used to determine the final watermark bit value to obtain a one-dimensional watermark sequence. The watermark acquisition module is used to perform dimensionality upscaling and descrambling on the extracted one-dimensional watermark sequence to obtain the final binarized watermark image.

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