A method for cross-network transmission and fusion of map symbols and annotations

Abstract

A method for cross-network transmission and fusion of map symbols and annotations, comprising step 1: deploying multiple sets of sending-end GIS systems; controlling the opening or closing of base maps and map symbols and annotation layers; step 2: deploying front-end equipment and fusion-end GIS systems in another network environment; step 3: setting control points in the sending-end GIS system and the fusion-end GIS system; step 4: receiving real-time video, identifying map symbols and annotations, and sending map symbols and annotation data to a data encryption module; step 5: the data encryption module encrypts the vector file and transmits it to a data decryption device; step 6: the data decryption device decodes the vector file and fuses and displays all map symbols and annotation layers on the fusion-end GIS system. The present invention solves the problem of cross-network transmission of map symbols and annotation elements.

Description

Technical Field

[0001] The present invention relates to the field of cross-network data transmission, and in particular to a method suitable for cross-network transmission and fusion of map symbols and annotations. Background Art

[0002] With the advancement of intelligent construction, public security, military industry, scientific research institutions and other units have generated a lot of confidential map data and established a large number of confidential geographic information systems (GIS). In order to ensure the confidentiality, security, integrity, non-repudiation and high availability of these map data and GIS systems, these map data and GIS systems are mostly deployed in confidential networks, private networks and special networks. Some top-secret map data and GIS systems are deployed in non-network devices, and even some map data are saved in paper form.

[0003] These maps and GIS systems cannot be transmitted over the network at will, so in daily work, multiple maps are usually drawn and multiple GIS systems are built in different network environments for the same area according to different business goals. Since maps can be divided into geographic environment base maps and map symbols and annotations, these two usually appear on the same map at the same time. The areas represented by these maps are exactly the same, only the map symbols and annotations are different, and it is the map symbols and annotations that cause the different levels of confidentiality of the maps, so they cannot be transmitted arbitrarily over the network, which not only causes system redundancy, but also prevents the map data from playing a greater role.

[0004] Invention patent application CN202010601820.1 (publication number CN111832329A, publication date 2020.10.27) discloses a one-way cross-network transmission method based on QR two-dimensional code, which converts the file information of the sending end into a two-dimensional code image, and the receiving end uses a camera to scan the two-dimensional code image generated by the sending end. The two-dimensional code receiving software pre-processes the image captured by the camera, calculates the integral image of the image and extracts the Haarlike feature, which is input into the trained cascade Adaboost classifier, and uses the Zbar two-dimensional code detection algorithm to parse the results of the cascade classifier recognition to obtain the sent file. The invention application of the one-way cross-network transmission method based on QR two-dimensional code adopts the two-dimensional code image transmission method, which has low transmission efficiency and a small amount of information stored in the two-dimensional code. The map file generally has a large amount of data, and multiple two-dimensional codes need to be spliced ​​to complete the transmission of the entire map file, which increases the two-dimensional code recognition time and file conversion time, and reduces the file transmission efficiency.

[0005] Invention patent application CN201911273249.9 (application publication number CN111062302 A, publication date April 24, 2020) discloses a method for exchanging data between physically isolated internal and external networks based on a combination of icon recognition and OCR. The method splits and encodes the data to be exchanged, and displays the data information of each encoded data packet on the intranet display screen. The camera collects the screen data information image, and obtains the data of the data packet to be exchanged through icon recognition, OCR recognition and data decoding; encodes the data packet to be exchanged, and displays the data information of each encoded data packet on the display screen. The camera collects the screen data information image, and obtains the data of the data packet to be compared through icon recognition, OCR recognition and data decoding, and compares it with the data packet to be exchanged. If they are the same, the data exchange is correct, and the display data information on the screen of the system device is switched. The disadvantages of this method are:

[0006] There is a delay problem and it cannot adapt to the real-time update frequency of the map. Map data has the characteristics of real-time update. Map elements including location and route change with the changes of real entities. However, this method needs to convert the map file into a data packet first during the data conversion process. Figure 1 If the map data is being updated continuously, it cannot be transmitted in real time.

[0007] As can be seen from the above, the main problems of the background technology are:

[0008] 1. Low transmission efficiency. The main drawback of encoding files into QR codes for cross-network map data transmission is that the amount of information stored in QR codes is small, while map files generally have large amounts of data. Multiple QR codes need to be spliced ​​together to complete the transmission of the entire map file, which increases the QR code recognition time and file conversion time, and reduces file transmission efficiency;

[0009] 2. Limited usage scenarios. When using online maps such as Baidu Maps and Amap, it is not possible to download map data separately, so the method of converting it into a QR code cannot be used;

[0010] The difficulty of solving the above problems and defects is: transmission efficiency and usage scenarios are relatively difficult to solve. For low transmission efficiency, it is necessary to optimize the data format, reduce the number of data encoding and decoding, and design a more efficient transmission method. For limited usage scenarios, it is necessary to design a more general transmission method suitable for map data transmission.

[0011] The significance of solving the above problems and defects is: solving the above problems can ensure the real-time transmission of maps, ensure the timeliness of map data, and make the use of scenarios more extensive.

[0012] The urgent problem to be solved now is: how to ensure that confidential map data and GIS systems are safe, reliable and physically isolated, and at the same time, transmit and integrate multi-source data and systems in real time and efficiently, so that multiple maps with the same base map can be integrated into one map to display all map symbols and annotations. Summary of the invention

[0013] The purpose of the present invention is to disclose a method suitable for cross-network transmission and fusion of map symbols and annotations.

[0014] The technical solution for achieving the purpose of the present invention is:

[0015] A method for cross-network transmission and fusion of map symbols and annotations, comprising the following steps:

[0016] Step 1: Deploy multiple sending-end GIS systems in network environment 1-network environment n.

[0017] The GIS system has a layer control function, which is used to control the opening or closing of the base map and map symbols and annotation layers. The base map is a map that can show the geographical environment of an area, such as a remote sensing image map or a topographic map. Map symbols and annotations refer to points, routes, and regional map elements related to certain businesses. The map symbols and annotations to be transmitted are displayed in the sending GIS system. The data types include point, line, and surface vector types, as well as text elements. The text elements include latitude and longitude, azimuth, and text annotations.

[0018] The network environment is the Internet, confidential network, private network, special network and no network.

[0019] Step 2: Deploy front-end shooting equipment, data processing equipment, data decryption equipment and a fusion-end GIS system in the network environment n+1; the data processing equipment consists of an image recognition module and a data encryption module.

[0020] Among them, the network environment where the front-end shooting equipment and data processing equipment are located is the Internet, a confidential network, a private network, or a special network.

[0021] The front-end shooting device is used to shoot the multiple sending-end GIS systems described in step 1. Each sending-end GIS system has and only has one front-end shooting device for shooting, and the sending-end GIS system interface needs to be shot completely. The higher the resolution of the front-end shooting device, the clearer the picture, and the clearer the map elements after transmission. The front-end shooting device has a real-time video transmission function, and transmits the shot picture to the data processing device.

[0022] Among them, the fusion-end GIS system needs to be able to display the geographic base map, and the projection method of the base map should be consistent with the map of the sending-end GIS system. If the projection methods are different, the projection method can be adjusted through the GIS system.

[0023] The data decryption device supports decoding map data and sending it to the fusion end GIS system.

[0024] Step 3: Deploy control points in the sending GIS system and the fusion GIS system.

[0025] Open the base maps of the sending GIS system and the fusion GIS system at the same time, use the drawing function of the GIS system to mark four control points, and write the longitude and latitude coordinates of the current control points next to the vertices. The longitude and latitude coordinates can be obtained through the GIS system. The coordinate text of the four control points and the map elements to be transmitted must be within the rectangular range formed by the four control points, because this rectangle is the effective range of the transmitted image.

[0026] After the control points are laid out, the base map layer in the sending GIS system will be hidden, and only the socio-economic map elements, control rectangles, image control points and their coordinate numbers to be transmitted will be displayed on the system interface. The colors of the rectangles and coordinate texts should have a large contrast with the background image color to facilitate subsequent image recognition.

[0027] Step 4: The data processing device receives the real-time video images sent back by each front-end shooting device, uses the image recognition module to identify the map symbols and annotations, four control points and their coordinates, converts the map symbols and annotations into a coordinate data stream format and sends it to the data encryption module.

[0028] Each frame image of the transmitted video is read, four control points in the frame image are extracted and perspective transformation is performed.

[0029] First extract the screen image, then extract the control points. Use the two-time rectangle extraction method, first threshold the image, then perform image, edge detection, contour extraction, convex hull detection, and corner point detection to obtain the coordinates of the four corners of the screen, and then establish a coordinate transformation matrix through the positions of the four corners. The final result is obtained through matrix operations, so that the map elements to be transmitted are flipped from an oblique position to a parallel position and spread over each frame of the image. The image is stretched with the four control points as the vertices of the video frame, so that the transmission elements can fill the video frame.

[0030] Use OCR text recognition technology to identify the longitude and latitude coordinates next to the control point, read the numbers and assign the longitude and latitude to the corresponding control point.

[0031] Using OCR text recognition technology, identify the small range of text on the right side of the control point, and assign the recognized text to the control point according to the x and y coordinate values.

[0032] The socio-economic map elements in the image are identified, the map elements are divided into line elements, surface elements and text elements, and vectorized separately.

[0033] The features on the map can be divided into three categories: points, lines and surfaces. However, since point features are represented by surface icons, point feature recognition is merged into surface feature recognition.

[0034] First, identify the text elements, use OCR text recognition technology to identify all text except for a small range of text near the control point, and record the content of all text.

[0035] Then identify the line elements, through the automatic extraction method of line symbols based on the characteristics of segment connected bodies, starting from the correlation between image pixels, first aggregate the dot matrix image, transform it into a segment description with basic classification characteristics of vector graphics and extract the topological relationship between them, then eliminate independent point-like connected bodies according to the characteristic size of the connected bodies, including various point-like symbols that are not represented in proportion, such as houses, bell towers, tombs, etc., and extract the connected bodies that are definitely line symbols. Then perform shape analysis on the remaining figures, remove text information and surface areas, and finally perform topological relationship analysis on the figures, remove connected bodies with complex topological relationships, and finally obtain To the line symbol, the line symbol extraction is completed, but due to the influence of factors such as the intersection or adhesion of line symbols, the connected body and the line symbol are not one-to-one. For example, due to the intersection of lines, a connected body contains two or even more line symbols. In order to avoid the processing of intersecting lines during vectorization, this method divides the connected body into several different curve segments according to the node graph segments, and vectorizes the curve segments separately, and then divides the connected body into several different curve segments according to the node graph segments, and vectorizes the curve segments separately. Finally, for the curve segments, the fitting method of the center point chain of the scanning string is adopted, and the fractal successive subdivision method is used for vectorization.

[0036] Finally, the raster-to-polygon method is used to identify the surface features and convert them into vectors.

[0037] Convert all current graphics from screen coordinates to WGS84 coordinates

[0038] Given the length (a) and height (b) of the screen, and the range of the geographic coordinate area (maxLon, minLon, maxLat, minLat), we can calculate:

[0039] scaleX = ((maxLon-minLon)*3600) / a;

[0040] scaleY = ((maxLat-minLat)*3600) / b;

[0041] The formula for converting screen coordinates to longitude and latitude coordinates is:

[0042] lon = X * scaleX / 3600 + minLon;

[0043] lat = maxLat - Y* scaleY / 3600.

[0044] a: screen pixel length, b: screen pixel height;

[0045] maxLon: the maximum longitude of the map element, minLon: the minimum longitude of the map element;

[0046] maxLat: the maximum latitude of the map element, minLat: the minimum latitude of the map element;

[0047] scaleX: the number of longitude seconds represented by each pixel on the x-axis, scaleY: the number of latitude seconds represented by each pixel on the y-axis;

[0048] lon: the longitude coordinate of the map feature after conversion, lat: the latitude coordinate of the map feature after conversion;

[0049] X: The x-axis coordinate value of the map element in the screen coordinate system. Y: The y-axis coordinate value of the map element in the screen coordinate system.

[0050] Step 5: The data encryption module in the data processing device encrypts the vector file and transmits it to the data decryption device

[0051] Setting the key

[0052] There is a password string S = C1C2C3……C with a length of m (m>1) m , map the string to a real number x0 between (0, 1) according to the given operation, and use x0 as the initial value of the chaotic map.

[0053] Forming an encryption key stream

[0054] Taking the key x0 as the initial value,

[0055] x k+1 = μx k (1- x k )

[0056] Repeated iterations are performed to generate a random sequence of sufficient length {x k , k = 0, 1, 2, 3...}, for a random sequence { x k , k=0,1,2,3,...} k , starting from the first non-zero digit after the decimal point, take 9 digits in sequence to form a long integer data L dk , and then for this long integer data L dk Perform a modulo operation to obtain an integer data d between [0, 255] k1 After all elements are processed, the resulting integer data sequence {dk1 , k=0,1,2,3,…} as the encryption key stream.

[0057] File encryption

[0058] Convert the vector map data file into binary file format and extract each byte stream {m k , k = 0, 1, 2, 3, ...} and the encryption key stream {d k1 , k=0, 1, 2, 3, ...} perform "XOR" operation to generate a ciphertext stream in the form of garbled code {p k , k =0, 1, 2, 3, ...}, that is, p k =m k⊕ d k1 , complete the encryption of the entire data file.

[0059] Step 6: The data decryption device decodes the vector file and displays all map symbols and annotation layers on the fusion end GIS system.

[0060] Take the opposite operation as the encryption end and convert the ciphertext stream {p k , k = 0, 1, 2, 3, ...} and the decryption key stream {d k2 , k=0, 1, 2, 3, ...} perform "XOR" operation to restore the plaintext stream {m k , k=0, 1, 2, 3, …}, complete the decryption of the entire data file; open the vector file in the fusion end GIS system, display the decrypted vector data, and complete the cross-network transmission of map elements.

[0061] m k : Byte stream before encryption

[0062] d k1 : Encryption key stream

[0063] d k2 : Decryption key stream

[0064] p k : Encrypted ciphertext stream

[0065] k: byte stream length

[0066] x0, x k+1 , L dk : Encrypt intermediate results

[0067] The present invention solves the problems existing in the prior art and realizes real-time and efficient transmission and fusion of multi-source data and systems while ensuring that confidential map data and GIS systems are safe, reliable and physically isolated, so that multiple maps with the same base map can be merged into one map to display all map symbols and annotations.

[0068] Compared with the prior art, the image transmission recognition method of the present invention has the following beneficial effects:

[0069] 1. Solved the problem of cross-network transmission of map symbols and annotation elements. That is, when GIS systems in different networks use the same geographic environment base map, the system merges the map symbols and annotations on all maps into one map for display, while keeping the map unchanged and the spatial position correct.

[0070] 2. By shooting, the high-density network is not directly connected to the low-density network, ensuring the compliance and security of data transmission.

[0071] 3. Encrypt the identified map elements during transmission to ensure the security of map data transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Figure 1 It is a flowchart of the present invention.

[0073] Figure 2 A block diagram of a module for implementing the method of the present invention is shown below:

[0074] Figure 3 Schematic diagram of a system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0075] The present invention will be further described below through specific implementation modes in conjunction with the accompanying drawings. The following embodiments or drawings are a best implementation mode of the present invention and are used to illustrate and understand the present invention, but are not used to limit the scope of the present invention.

[0076] In conjunction with the accompanying drawings, the method of using the present invention is as follows:

[0077] like Figure 1 and Figure 2 As shown, during a large-scale event, a certain confidentiality department will deploy multiple security and prevention plans for a region. These plans are displayed in the form of map symbols and annotations. Some security plans have a low confidentiality level and are used in the GIS system of a certain confidentiality network; they can only be used in a GIS system without a network. In actual applications, due to network problems, all plans for the same event cannot be displayed on one map, resulting in the commander having to pay attention to multiple GIS systems at the same time to understand the security measures around the activity area, which is not only inconvenient for command and dispatch, but also causes a waste of information resources. The present invention has invented a new technical method to address the problem that map elements cannot be transmitted across networks. The specific implementation method is as follows:

[0078] Step 1: Deploy multiple sending-end GIS systems S1 in network environments 1-n.

[0079] In a certain confidential network, there is a GIS system that stores low-level regional blockade locations and road control arrangement maps, and on a stand-alone device, there is a GIS system that stores the route map and location distribution map of the event site. The base map used in these two GIS systems is the same remote sensing image map, and the system supports displaying the latitude and longitude coordinates and text annotation information of each point on the map, and supports the plotting of line features.

[0080] Step 2: Deploy front-end shooting equipment, data processing equipment, data decryption equipment and a fusion terminal GIS system S2 in the network environment n+1; the data processing equipment consists of an image recognition module and a data encryption module.

[0081] In order to display the regional control layer, road control layer and police force arrangement layer in the GIS system of a certain confidential network and stand-alone equipment in a GIS system on an Internet computer, two sets of cameras need to be deployed on the Internet to shoot the GIS system of a certain confidential network and stand-alone equipment respectively, and the GIS system interface is shot completely during shooting. The base map used in the fusion end Internet GIS system and the above two GIS systems is the same remote sensing image map, and the system supports the display of the latitude and longitude coordinates and text annotation information of each point on the map, and supports the plotting of point, line and surface elements.

[0082] Step 3: Deploy control point S4 in the sending end GIS system and the fusion end GIS system.

[0083] At the same time, open the base map of a certain confidentiality network and a stand-alone GIS system, use the drawing function of the GIS system to draw a rectangle to include the map elements of regional blockade, road control and police force arrangement, write the longitude and latitude coordinates of the current control point next to the vertices of the rectangle, and the coordinate text is located inside the rectangle. After the control points are arranged, hide the remote sensing image layer in the confidentiality network and the stand-alone GIS system, and only display the regional blockade, road control and police force arrangement, control rectangle, image control point and its coordinates to be transmitted on the system interface.

[0084] Step 4: The data processing device receives the real-time video sent back by each front-end shooting device, uses the image recognition module to identify the map symbols and annotations, four image control points and their coordinates, converts the map symbols and annotations into a coordinate data stream format and sends it to the data encryption module S4.

[0085] 1. Read each frame of the video, extract the four corners of the control rectangle and perform perspective transformation.

[0086] First, extract the screen images of the equipment in a certain confidential network and the stand-alone equipment, and then extract the control rectangle in the GIS system. Use the two-time rectangle extraction method, first threshold the image, then perform image, edge detection, contour extraction, convex hull detection, and corner point detection to obtain the coordinates of the four corners of the screen, and then establish a coordinate transformation matrix through the positions of the four corners. The final result is obtained through matrix operation, so that the image is flipped from an inclined position to a parallel position and filled with each frame of the image. At this time, the control points are the four vertices of the captured image.

[0087] 2. Identify the longitude and latitude coordinate numbers next to the control point, read the numbers and assign the longitude and latitude to the corresponding control point.

[0088] Use OCR text recognition technology to identify small-range text near the control point, and assign the recognized text to the control point according to the x and y coordinate values.

[0089] 3. Identify the socio-economic map elements in the image, divide the map elements into line elements, surface elements and text elements, and vectorize them separately.

[0090] First, identify the text elements, use OCR text recognition technology to identify all text except for a small range of text near the control point, and record the content of all text.

[0091] Then identify the line elements, through the automatic extraction method of line symbols based on the characteristics of segment connected bodies, starting from the correlation between image pixels, first aggregate the dot matrix image, transform it into a segment description with basic classification characteristics of vector graphics and extract the topological relationship between them, then eliminate independent point-like connected bodies according to the characteristic size of the connected bodies, including various point-like symbols that are not represented in proportion, such as houses, bell towers, tombs, etc., and extract the connected bodies that are definitely line symbols. Then perform shape analysis on the remaining figures, remove text information and surface areas, and finally perform topological relationship analysis on the figures, remove connected bodies with complex topological relationships, and finally obtain To the line symbol, the line symbol extraction is completed, but due to the influence of factors such as the intersection or adhesion of line symbols, the connected body and the line symbol are not one-to-one. For example, due to the intersection of lines, a connected body contains two or even more line symbols. In order to avoid the processing of intersecting lines during vectorization, this method divides the connected body into several different curve segments according to the node graph segments, and vectorizes the curve segments separately, and then divides the connected body into several different curve segments according to the node graph segments, and vectorizes the curve segments separately. Finally, for the curve segments, the fitting method of the center point chain of the scanning string is adopted, and the fractal successive subdivision method is used for vectorization.

[0092] Finally, the raster-to-polygon method is used to identify the surface features and convert them into vectors.

[0093] 4. Convert all current graphics from screen coordinates to WGS84 coordinates

[0094] Given the length (a) and height (b) of the screen, and the range of the geographic coordinate area (maxLon, minLon, maxLat, minLat), we can calculate:

[0095] scaleX = ((maxLon-minLon)*3600) / h;

[0096] scaleY = ((maxLat-minLat)*3600) / y;

[0097] The formula for converting screen coordinates to longitude and latitude coordinates is:

[0098] lon = X * scaleX / 3600 + minLon;

[0099] lat = maxLat - Y* scaleY / 3600.

[0100] Step 5: The data encryption module in the data processing device encrypts the vector file and transmits it to the data decryption device S5

[0101] 1. Set the key

[0102] There is a password string S = C1C2C3……C with a length of m (m>1) m , map the string to a real number x0 between (0, 1) according to the given operation, and use x0 as the initial value of the chaotic map.

[0103] 2. Form an encryption key stream

[0104] Taking the key x0 as the initial value,

[0105] x k+1 = μx k (1- x k )

[0106] Repeated iterations are performed to generate a random sequence of sufficient length {x k , k = 0, 1, 2, 3. ...}, for a random sequence {x k , k=0,1,2,3,...} k , starting from the first non-zero digit after the decimal point, take 9 digits in sequence to form a long integer data L dk , and then for this long integer data L dk Perform a modulo operation to obtain an integer data d between [0, 255] k1 After all elements are processed, the resulting integer data sequence {d k1 , k=0, 1, 2, 3, …} as the encryption key stream.

[0107] 3. File encryption

[0108] Convert the vector map data file into binary file format and extract each byte stream {m k , k = 0, 1, 2, 3, ...} and the encryption key stream {d k1 , k=0, 1, 2, 3, ...} perform "XOR" operation to generate a ciphertext stream in the form of garbled code {p k , k =0, 1, 2, 3, ...}, that is, p k = m k⊕ d k1 , complete the encryption of the entire data file.

[0109] Step 6: The data decryption device decodes the vector file and displays all map symbols and annotation layers on the fusion end GIS system S6

[0110] Take the opposite operation as the encryption end and convert the ciphertext stream {P k , k = 0, 1, 2, 3, ...} and the decryption key stream {d k2 , k=0, 1, 2, 3, ...} perform "XOR" operation to restore the plaintext stream {m k , k=0, 1, 2, 3, …}, complete the decryption of the entire data file; open the vector file in the fusion end GIS system, display the decrypted vector data, and complete the cross-network transmission of map elements.

[0111] experiment

[0112] According to the method for cross-network transmission and fusion of map symbols and annotations of the present invention, a practical experiment was conducted. Table 1 is a practical experiment table of the present invention.

[0113] Table 1: Actual test table of the present invention

[0114]

[0115] As shown in Table 1, the delay time for sending and receiving map update information of the present invention is 3-7 seconds.

[0116] Figure 3 is a system schematic diagram of an embodiment of the present invention, such as Figure 3 As shown, the system implementing the present invention includes: a sending-end GIS system, a front-end shooting device, a data processing device, a data decryption device, and a fusion-end GIS system.

[0117] The above description is the best embodiment based on the concept and working principle of the invention. The above embodiment should not be understood as limiting the scope of protection of the claims of the present invention, and other implementations and combinations of implementations of the present invention are within the scope of protection of the present invention.

Claims

1. A method for cross-network transmission and fusion of map symbols and annotations, comprising the following steps: Step 1: deploy multiple sending-end GIS systems in network environment 1-network environment n; the GIS system has a layer control function, which is used to control the opening or closing of the base map and map symbols and annotation layers; Step 2: Deploy front-end shooting equipment, data processing equipment, data decryption equipment and a set of integrated terminal GIS system in the network environment n+1; the data processing equipment consists of an image recognition module and a data encryption module; in, The network environment where the front-end shooting equipment and data processing equipment are located can be the Internet, a confidential network, a private network, or a special network; Step 3: Arrange control points in the sending GIS system and the fusion GIS system, open the base maps of the sending GIS system and the fusion GIS system at the same time, use the drawing function of the GIS system to mark four control points, and write the longitude and latitude coordinates of the current control points next to the vertices. The longitude and latitude coordinates can be obtained through the GIS system. The coordinate texts of the four control points and the map elements to be transmitted must be within the rectangular range formed by the four control points; After the control points are laid out, the base map in the sending GIS system is hidden, and only the socio-economic map elements, control rectangles, control points and their coordinate texts to be transmitted are displayed on the system interface. The colors of the rectangles and coordinate texts should have a large contrast with the background image color. Step 4: The data processing device receives the real-time video images sent back by each front-end shooting device, uses the image recognition module to identify the map symbols and annotations, four control points and their coordinates, converts the map symbols and annotations into a coordinate data stream format and sends it to the data encryption module; Step 5: The data encryption module in the data processing device encrypts the vector file and transmits it to the data decryption device; Step 6: The data decryption device decodes the vector file and displays all map symbols and annotation layers on the fusion-end GIS system.

2. The method for cross-network transmission and fusion of map symbols and annotations according to claim 1, characterized in that In the step 1: The GIS system has a layer control function, which is used to control the opening or closing of the base map and map symbols and annotation layers; the base map is a map that can display the geographical environment of an area, such as a remote sensing image map or a topographic map, and the map symbols and annotations refer to points, routes, and regional map elements related to certain businesses; the map symbols and annotations to be transmitted are displayed in the sending GIS system, and the data types include point, line, and surface vector types, as well as text elements, which include latitude and longitude, azimuth, and text annotations.

3. The method for cross-network transmission and fusion of map symbols and annotations according to claim 1 is characterized in that In the step 2: the front-end shooting device is used to shoot the multiple sending-end GIS systems described in step 1. Each sending-end GIS system has one and only one front-end shooting device for shooting, and the sending-end GIS system interface needs to be shot completely; the front-end shooting device has a real-time video transmission function, and transmits the shot image to the data processing device.

4. The method for cross-network transmission and fusion of map symbols and annotations according to claim 1, characterized in that In the step 4: 1) Read each frame of the transmitted video, extract the four control points of the control rectangle in the frame image and perform perspective transformation; 2) Use OCR text recognition technology to identify the longitude and latitude coordinates next to the control point, read the numbers and assign the longitude and latitude to the corresponding control point; 3) Identify the socio-economic map elements in the image, divide the map elements into line elements, surface elements and text elements, and vectorize them separately; 4) Convert all current graphics from screen coordinates to WGS84 coordinates, Given the length (a) and height (b) of the screen, and the range of the geographic coordinate area (maxLon, minLon, maxLat, minLat), we can calculate: scaleX = ((maxLon-minLon)*3600) / a; scaleY = ((maxLat-minLat)*3600) / b; The formula for converting screen coordinates to longitude and latitude coordinates is: lon = X * scaleX / 3600 + minLon; lat = maxLat - Y* scaleY / 3600, where: a: screen pixel length b: screen pixel height; maxLon: the maximum longitude of the map element, minLon: the minimum longitude of the map element; maxLat: the maximum latitude of the map element, minLat: the minimum latitude of the map element; scaleX: the number of longitude seconds represented by each pixel on the x-axis, scaleY: the number of latitude seconds represented by each pixel on the y-axis; lon: the longitude coordinate of the map feature after conversion, lat: the latitude coordinate of the map feature after conversion; X: The x-axis coordinate value of the map element in the screen coordinate system. Y: The y-axis coordinate value of the map element in the screen coordinate system.

5. The method for cross-network transmission and fusion of map symbols and annotations according to claim 1, characterized in that In the step five: 1) Set the key There is a password string S = C1C2C3……C with a length of m (m>1) m , map the string to a real number x0 between (0, 1) according to the given operation, and use x0 as the initial value of the chaotic map; 2) Form an encryption key stream, using the key x0 as the initial value, and x k+1 =μx k (1-x k ) Repeated iterations are performed to generate a random sequence of sufficient length {x k , k = 0, 1, 2, 3, ...}, for a random sequence { x k , k=0, 1, 2, 3, ...} k , starting from the first non-zero digit after the decimal point, take 9 digits in sequence to form a long integer data L dk , and then for this long integer data L dk Perform a modulo operation to obtain an integer data d between [0, 255] k1 ; After all elements are processed, the resulting integer data sequence {d k1 , k=0, 1, 2, 3, ...} as the encryption key stream; 3) File encryption, convert the vector map data file into a binary file format, and extract each byte stream {m k , k = 0, 1, 2, 3, ...} and the encryption key stream {d k1 , k=0, 1, 2, 3, ...} perform "XOR" operation to generate a ciphertext stream in the form of garbled code {p k , k =0, 1, 2, 3, ...}, that is, p k = m k⊕ d k1 , complete the encryption of the entire data file.

6. The method for cross-network transmission and fusion of map symbols and annotations according to claim 1, characterized in that In step 6: take the opposite operation to the encryption end and convert the ciphertext stream {p k , k = 0, 1, 2, 3, ...} and the decryption key stream {d k2 , k=0, 1, 2, 3, ...} perform "XOR" operation to restore the plaintext stream {m k , k=0, 1, 2, 3, …}, complete the decryption of the entire data file; open the vector file in the fusion end GIS system, display the decrypted vector data, and complete the cross-network transmission of map elements.

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