A method and device for three-dimensional registration and fusion of building white model data and DEM data

Abstract

The application discloses a kind of three-dimensional registration fusion method and device of building white mould data and DEM data, method includes to the DEM data and building data obtained are registered, building data is carried out coordinate transformation, obtain the result of registration processing;Then, according to the result of registration processing, the corresponding relationship between building surface and DEM data is constructed;Then, according to the corresponding relationship calculation DEM elevation information value;Further according to the DEM elevation information value, update the elevation information of each building surface area DEM grid, and in vertical direction match building and DEM, obtain matching result;Finally according to the matching result, building edge periphery is carried out smoothing processing, complete building white mould data and the three-dimensional registration fusion of DEM data.The application can quickly and effectively solve the problem that data boundary cannot be well configured and fused caused by mechanical splicing combination of white mould data and DEM data, is efficient and accurate, can be widely applied in computer technology field.

Description

Technical Field

[0001] This invention relates to the field of computer technology, and in particular to a method and apparatus for three-dimensional registration and fusion of architectural white model data and DEM data. Background Technology

[0002] 3D spatial analysis and visualization of geospatial information are more intuitive than 2D displays, offering spatial analysis functions that 2D GIS cannot provide, such as daily elevation analysis, viewpoint analysis, and inundation analysis. Due to the high cost of producing detailed and intermediate models, most existing 3D modeling is based on 2D planar building data, using building height as a reference, and extruding it into a white model for 3D analysis and display. Performing 3D registration and fusion between the 3D building white model and the corresponding digital elevation model will more perfectly present the 3D digital results while reducing data production processes and costs.

[0003] With the development of oblique photogrammetry, laser point cloud, UAV aerial surveying, cloud computing, and big data technologies, 3D spatial data has been widely applied to various industries, such as 3D cities, 3D traffic simulation, and digital twin cities. While oblique photogrammetry and laser point cloud technologies can quickly construct realistic 3D scenes, they suffer from the problem of fragmented and isolated data. Using white models of urban buildings and urban DEM data allows for spatial analysis and 3D visualization of specific targets; however, the 3D white model data often doesn't integrate well with the DEM data, potentially resulting in gaps. At sloping locations, some white model data may appear suspended in the air while others are embedded within the DEM. These issues diminish the 3D rendering effect.

[0004] Urban 3D white model data is stored in vector form, while urban DEM data is generally stored in raster form. Achieving the registration and fusion of 3D vector data and spatial raster data is the key and difficult point to eliminate the gap at the junction of urban building white model and urban DEM data.

[0005] Currently, many methods for registering and integrating urban building white models and urban DEM data only perform planar position registration, with relatively crude elevation adjustments. In some cases, to eliminate the gap between the white model and the DEM, the reference plane of the white model is often set lower, allowing the white model data to be directly inserted into the DEM data, essentially burying part of the building underground. In addition, manual modifications are made to the contact points between each urban building and the DEM, which consumes a lot of manpower and time, and the result may not be that the gap between the two types of data can be completely resolved.

[0006] If urban building white model data can be quickly and batch registered and merged with urban DEM data in 3D space, it will solve the problem of rapid building modeling and enable urban building white models and urban DEM data to be perfectly displayed in 3D space engine. Summary of the Invention

[0007] In view of this, embodiments of the present invention provide an efficient and accurate three-dimensional registration and fusion method and apparatus for architectural white model data and DEM data.

[0008] One aspect of this invention provides a method for three-dimensional registration and fusion of architectural white model data and DEM data, comprising:

[0009] The acquired DEM data and building data are registered, and the coordinates of the building data are transformed to obtain the registration result.

[0010] Based on the registration process results, a correspondence between building surfaces and DEM data is constructed.

[0011] Calculate the DEM elevation information value based on the correspondence;

[0012] Based on the DEM elevation information value, update the elevation information of the DEM raster within each building area, and match the building and DEM in the vertical direction to obtain the matching result;

[0013] Based on the matching results, the outer edges of the building are smoothed to complete the three-dimensional registration and fusion of the building white model data and the DEM data.

[0014] Optionally, the registration process for the acquired DEM data and building data, which involves transforming the building data to obtain the registration result, includes:

[0015] Perform projection transformation on the DEM data obtained from the survey;

[0016] Find the corresponding first feature point coordinate set on the DEM data;

[0017] Based on the building data, find the corresponding set of coordinates of the second feature points on the building surface;

[0018] Establish the transformation relationship between the first feature point coordinate set and the second feature point coordinate set, perform coordinate transformation on the building data, and obtain the registration result.

[0019] Optionally, constructing the correspondence between building surfaces and DEM data based on the registration process includes:

[0020] Based on the division of DEM raster data according to building surface data, DEM rasters located inside a building surface and intersecting with the building edge are marked, and the correspondence between building surface data and DEM raster data is established.

[0021] Optionally, calculating the DEM elevation information value based on the correspondence includes:

[0022] Traverse the data in the correspondence to obtain the grid coordinate sequence corresponding to one face of the building;

[0023] Based on the grid coordinate sequence of the DEM, obtain the elevation information of the corresponding grid location in the DEM grid data;

[0024] Calculate the mode of all DEM grid elevation information corresponding to one face of a building;

[0025] If the frequency of the mode is less than or equal to 0.1 times the number of grids corresponding to the building's face, then the median of the corresponding elevation information is calculated, and the DEM elevation information value is determined based on the median.

[0026] If the frequency of the mode is greater than 0.1 times the number of grids corresponding to the building's face, then the DEM elevation information value is determined based on the mode.

[0027] Optionally, the step of updating the elevation information of the DEM raster within each building area based on the DEM elevation information value, and matching the building and DEM in the vertical direction to obtain the matching result, includes:

[0028] Update the elevation information of the DEM data corresponding to the building surface, and make the building tangent to the DEM data at the corresponding location;

[0029] The height of the building itself is the height of the white model of the building.

[0030] Optionally, the step of smoothing the outer edge of the building based on the matching result to complete the three-dimensional registration and fusion of the building white model data and the DEM data includes:

[0031] For DEM grids that intersect with the building surface edge and adjacent DEM grids located outside all building surfaces, smoothing is performed perpendicular to the building edge and away from the building. The average value of the target point and the DEM grid in a specific direction of the adjacent grid is calculated, and the elevation information of the outer DEM grid in a specific direction is updated.

[0032] Another aspect of this invention provides a three-dimensional registration and fusion device for architectural white model data and DEM data, comprising:

[0033] The first module is used to perform registration processing on the acquired DEM data and building data, and to perform coordinate transformation on the building data to obtain the registration result.

[0034] The second module is used to construct the correspondence between building surfaces and DEM data based on the registration process results.

[0035] The third module is used to calculate the DEM elevation information value based on the correspondence.

[0036] The fourth module is used to update the elevation information of the DEM raster within each building area based on the DEM elevation information value, and to match the building and DEM in the vertical direction to obtain the matching result;

[0037] The fifth module is used to smooth the outer edge of the building based on the matching results, and complete the three-dimensional registration and fusion of the building white model data and the DEM data.

[0038] Another aspect of the present invention provides an electronic device, including a processor and a memory;

[0039] The memory is used to store programs;

[0040] The processor executes the program to implement the method described above.

[0041] Another aspect of this invention provides a computer-readable storage medium storing a program that is executed by a processor to implement the methods described above.

[0042] This invention also discloses a computer program product or computer program, which includes computer instructions stored in a computer-readable storage medium. A processor of a computer device can read the computer instructions from the computer-readable storage medium and execute the computer instructions, causing the computer device to perform the aforementioned method.

[0043] The embodiments of this invention first perform registration processing on the acquired DEM data and building data, transforming the building data to obtain the registration result. Next, based on the registration result, a correspondence between the building surfaces and the DEM data is established. Then, the DEM elevation information value is calculated based on the correspondence. Furthermore, based on the DEM elevation information value, the elevation information of the DEM raster within each building surface is updated, and the building and DEM are matched vertically to obtain a matching result. Finally, based on the matching result, the outer edges of the building are smoothed, completing the 3D registration and fusion of the building white model data and the DEM data. This invention can quickly and effectively solve the problem of poor configuration and fusion at data boundaries caused by mechanically piecing together white model data and DEM data, achieving high efficiency and accuracy. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 This is a flowchart illustrating the overall steps of an embodiment of the present invention;

[0046] Figure 2 A schematic diagram of DEM raster data;

[0047] Figure 3 This is a schematic diagram of the building's floor plan data. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0049] Precision model: A model that accurately represents the geometric structure of a building, shows many details of the building, and focuses on accurately representing some important architectural features.

[0050] Medium Model: In order to ensure the smooth operation of large-scale digital cities on the platform and to accurately represent the geometric structure of buildings, a model is created that can ignore some of the physical structure and simply represent some of the architectural landscape without affecting the real geometric structure of the buildings.

[0051] White model: A white model is a block model that ignores the detailed structure of the building, highlights the outer outline of the building and the general feeling of the roof, and is a simple model of the building.

[0052] DEM: Digital Elevation Model is a digital simulation of ground topography (i.e., a digital representation of the surface morphology of the terrain) achieved through limited terrain elevation data. It is a physical ground model that represents ground elevation using an ordered array of numerical values.

[0053] Registration refers to the matching of geographic coordinates of different images obtained using different imaging methods within the same region.

[0054] Fusion: combining, correlating, and integrating data and information from multiple sources to obtain a more accurate location or object.

[0055] Mode: The value that has a clear central tendency in the statistical distribution, representing the general level of the data.

[0056] This invention addresses the shortcomings of spatial analysis and visualization of urban building white model data and urban DEM data, and can quickly and effectively solve the problem of poor data boundary configuration and fusion caused by the mechanical combination of white model data and DEM data. It is particularly useful for the fusion of urban building white model data and urban DEM data in mountainous cities with significant topographic relief.

[0057] Specifically, such as Figure 1 As shown, the method of the present invention includes the following steps:

[0058] 1. Register DEM data and building data:

[0059] Generally, DEM data obtained through surveying has undergone corresponding projection transformations. This embodiment assumes that the DEM's coordinate system is a Gaussian 6-degree zone projection. The first feature point coordinate set Dset (XC1 YC1, XC2 YC2…XCn YCn) is located on the DEM data. Feature points are typically road intersections, landmark buildings, or river forks and confluences, etc. The corresponding second feature point coordinate set Bset (xxc1 yyc1, xxc1 yyc1…xxcn yycn) is also located on the building surfaces. The transformation relationship between Bset and Dset is established, and the corresponding building data is transformed. The number of feature points can be appropriately increased based on the required registration accuracy.

[0060] like Figure 2 As shown in (a) and (b), (a) represents DEM raster data with elevation attributes, and (b) represents DEM raster data. Additionally, building surface data is as follows: Figure 3 As shown.

[0061] Assuming that the geometric distortion of remote sensing images is a combination of compression, twisting, scaling, shifting, and higher-order basic deformations, this effect can be simulated using first-order, second-order, or higher-order bivariate polynomials.

[0062] Implementation process: Ground control point data is used to mathematically fit the geometric distortion of remote sensing imagery. Then, the coefficients of a bivariate polynomial are calculated using the least squares method. This establishes a mathematical mapping relationship between the original image space and the actual geographic coordinate space, and the geometric static correction of the imagery is performed based on this polynomial.

[0063] Establish the correspondence between the coordinates of the two graphs;

[0064]

[0065] X c Y c xxc and yyc are the coordinates after transformation; xxc and yyc are the coordinates before transformation.

[0066] Typically, the mapping f is a bivariate polynomial of degree n, and the specific method for finding it is as follows:

[0067]

[0068] The least squares method is used to fit and calculate the coefficients (where L is the number of control points to be calculated).

[0069]

[0070]

[0071] Using the known control point data, the coefficients of the polynomial in the matrix are solved, and the f-mapping relationship is finally obtained.

[0072] 2. Establish the relationship between building facades and DEM data.

[0073] Traverse each building face; mark the DEM raster inside the building face (bx1 by1, bx2 by2, ..., bxn byn, bx1 by1) and intersecting with the edge of the building, and record the results in the set Dmap(B1, (X1 Y1, X2 Y2, ..., Xn Yn)). This process is equivalent to dividing the DEM raster data according to the building face data, and establishing the correspondence between the building face data and the DEM raster data Dmap.

[0074] The Dmap mapping relationship is shown in Table 1:

[0075] Table 1

[0076]

[0077] 3. Analyze and calculate reasonable DEM elevation information values ​​H

[0078] Iterate through the Map set data established in the previous step, and based on the building surface, obtain the raster coordinate sequence (X1 Y1, X2 Y2...Xn Yn) corresponding to the building surface through the correspondence relationship Dmap established in step 2 above; then, based on the raster coordinate sequence of DEM, obtain the elevation information of the corresponding grid position in the DEM raster data; calculate the mode N of all DEM grid elevation information corresponding to the building surface;

[0079] If the number of occurrences of N is less than or equal to 0.1 times the number of grids corresponding to the building surface, then calculate the median K of the corresponding elevation information, and H = K;

[0080] If the number of occurrences of N is greater than 0.1 times the number of grids corresponding to the building surface, then H = N.

[0081] It should be noted that the header of the DEM data file will indicate the data unit, the number of rows and columns of the raster file, and the elevation zoom (HZoom), etc. The integer values ​​stored in the body of the file are the elevation information.

[0082] For example:

[0083] Header information:

[0084] NSDTF-DEM China Geospatial Data Exchange Format - Marker of Grid Data Exchange Format

[0085] Version number 1.0

[0086] M represents coordinate units, K represents kilometers, M represents meters, and D represents latitude and longitude in degrees.

[0087] 0.000000 Direction angle

[0088] 0.000000 Compression method: 0 indicates no compression, 1 indicates run-length encoding.

[0089] 39512435.000000 X-coordinate of the top left corner origin

[0090] 2743120.000000 Y-coordinate of the top left corner origin

[0091] 5.000000 Spacing in the X direction

[0092] 5.000000 Spacing in the Y direction

[0093] 985 rows

[0094] 1328 columns

[0095] The 100 elevation magnification setting allows elevation data to be stored as integers, such as with elevation accuracy down to the centimeter.

[0096] Below are the specific raster data values:

[0097] -99999 20738 19502 18176 16504 14833 13685 12564 11311 11307 11302 11298 11785 12149 12145 12140 12013 11763 11635 11630 11625 11621 11617 11612 11608 11603 11353 11102 11097 11093

[0100] It should be noted that the mode N is calculated as follows: the mode is the data that appears most frequently in a set of data. It is the original data in the set of data, not the corresponding frequency.

[0101] 4. Match buildings and DEMs in the vertical direction

[0102] The elevation information of the DEM data at the raster sequence (X1 Y1, X2 Y2……Xn Yn) corresponding to the building surface is updated to H, which is equivalent to the building being tangent to the DEM data at the location with elevation information H.

[0103] Update the building's elevation datum information to H. The building is built on a DEM at elevation H and is tangent to the DEM at elevation H. The building's height will be the height of the building's white model.

[0104] 5. Smooth the outer edges of the building.

[0105] For the DEM grid (XX1 YY1, XX2 YY2, ..., XXm YYm) intersecting with the building's edge P, and the DEM grid (XB1 YB1, XB2 YB2, ..., XBk YBk) located outside all building faces and adjacent to (XX1 YY1, XX2 YY2, ..., XXm YYm), smoothing is performed in the direction f perpendicular to the building's edge P and away from the building. The average value avgH of the adjacent grids of (X1Y1, X2 Y2, ..., Xm Ym) and (XB1 YB1, XB2 YB2, ..., XBk YBk) in the f direction is calculated. The elevation information of the outer DEM grid (XBf YBf) in the f direction is updated to avgH.

[0106] In summary, this invention can quickly and effectively solve the problem of poor data boundary configuration and fusion caused by mechanically piecing together white model data and DEM data. It is particularly useful for fusing white model data of urban buildings and urban DEM data in mountainous cities with significant topographic relief.

[0107] Compared with existing technologies, this invention can firstly effectively eliminate the gap between DEM data and building white model data; secondly, it can perform batch processing of DEM and building data, saving costs.

[0108] In some alternative embodiments, the functions / operations mentioned in the block diagrams may not occur in the order shown in the operation diagrams. For example, depending on the functions / operations involved, two consecutively shown blocks may actually be executed substantially simultaneously, or the blocks may sometimes be executed in reverse order. Furthermore, the embodiments presented and described in the flowcharts of this invention are provided by way of example to provide a more comprehensive understanding of the technology. The disclosed methods are not limited to the operations and logic flows presented herein. Alternative embodiments are contemplated in which the order of various operations is altered and sub-operations described as part of a larger operation are executed independently.

[0109] Furthermore, although the invention has been described in the context of functional modules, it should be understood that, unless otherwise stated, one or more of the described functions and / or features may be integrated into a single physical device and / or software module, or one or more functions and / or features may be implemented in a separate physical device or software module. It is also understood that a detailed discussion of the actual implementation of each module is unnecessary for understanding the invention. Rather, given the properties, functions, and internal relationships of the various functional modules in the apparatus disclosed herein, the actual implementation of the module will be understood within the scope of conventional skill of an engineer. Therefore, those skilled in the art can implement the invention as set forth in the claims using ordinary techniques without excessive experimentation. It is also understood that the specific concepts disclosed are merely illustrative and not intended to limit the scope of the invention, which is determined by the full scope of the appended claims and their equivalents.

[0110] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, essentially, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0111] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device.

[0112] More specific examples of computer-readable media (a non-exhaustive list) include: electrical connections (electronic devices) having one or more wires, portable computer disk drives (magnetic devices), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Furthermore, computer-readable media can even be paper or other suitable media on which the program can be printed, because the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in computer memory.

[0113] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0114] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0115] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

[0116] The above is a detailed description of the preferred embodiments of the present invention, but the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A method for three-dimensional registration and fusion of architectural white model data and DEM data, characterized in that, include: The acquired DEM data and building data are registered, and the coordinates of the building data are transformed to obtain the registration result. Based on the registration process results, a correspondence between building surfaces and DEM data is constructed. Calculate the DEM elevation information value based on the correspondence; Based on the DEM elevation information value, update the elevation information of the DEM raster within each building area, and match the building and DEM in the vertical direction to obtain the matching result; Based on the matching results, the outer edge of the building is smoothed to complete the three-dimensional registration and fusion of the building white model data and the DEM data; The step of constructing the correspondence between building surfaces and DEM data based on the registration process includes: Based on the division of DEM raster data according to building surface data, DEM rasters located inside a building surface and intersecting with the building edge are marked, and the correspondence between building surface data and DEM raster data is established. The step of calculating the DEM elevation information value based on the correspondence includes: Traverse the data in the correspondence to obtain the grid coordinate sequence corresponding to one face of the building; Based on the grid coordinate sequence of the DEM, obtain the elevation information of the corresponding grid location in the DEM grid data; Calculate the mode of all DEM grid elevation information corresponding to one face of a building; If the frequency of the mode is less than or equal to 0.1 times the number of grids corresponding to the building's face, then the median of the corresponding elevation information is calculated, and the DEM elevation information value is determined based on the median. If the frequency of the mode is greater than 0.1 times the number of grids corresponding to the building's face, then the DEM elevation information value is determined based on the mode.

2. The method for three-dimensional registration and fusion of architectural white model data and DEM data according to claim 1, characterized in that, The registration process for the acquired DEM data and building data, which involves transforming the coordinates of the building data to obtain the registration result, includes: Perform projection transformation on the DEM data obtained from the survey; Find the corresponding first feature point coordinate set on the DEM data; Based on the building data, find the corresponding set of coordinates of the second feature points on the building surface; Establish the transformation relationship between the first feature point coordinate set and the second feature point coordinate set, perform coordinate transformation on the building data, and obtain the registration result.

3. The method for three-dimensional registration and fusion of architectural white model data and DEM data according to claim 1, characterized in that, The step involves updating the elevation information of the DEM raster within each building area based on the DEM elevation information value, and matching the building and DEM in the vertical direction to obtain the matching result, including: Update the elevation information of the DEM data corresponding to the building surface, and make the building tangent to the DEM data at the corresponding location; The height of the building itself is the height of the white model of the building.

4. The method for three-dimensional registration and fusion of architectural white model data and DEM data according to claim 1, characterized in that, The step of smoothing the outer edge of the building based on the matching result to complete the 3D registration and fusion of the building white model data and DEM data includes: For DEM grids that intersect with the building surface edge and adjacent DEM grids located outside all building surfaces, smoothing is performed perpendicular to the building edge and away from the building. The average value of the target point and the DEM grid in a specific direction of the adjacent grid is calculated, and the elevation information of the outer DEM grid in a specific direction is updated.

5. An apparatus for implementing the three-dimensional registration and fusion method of architectural white model data and DEM data as described in any one of claims 1-4, characterized in that, include: The first module is used to perform registration processing on the acquired DEM data and building data, and to perform coordinate transformation on the building data to obtain the registration result. The second module is used to construct the correspondence between building surfaces and DEM data based on the registration process results. The third module is used to calculate the DEM elevation information value based on the correspondence. The fourth module is used to update the elevation information of the DEM raster within each building area based on the DEM elevation information value, and to match the building and DEM in the vertical direction to obtain the matching result; The fifth module is used to smooth the outer edge of the building based on the matching results, and complete the three-dimensional registration and fusion of the building white model data and the DEM data.

6. An electronic device, characterized in that, Including the processor and memory; The memory is used to store programs; The processor executes the program to implement the method as described in any one of claims 1 to 4.

7. A computer-readable storage medium, characterized in that, The storage medium stores a program that is executed by a processor to implement the method as described in any one of claims 1 to 4.

8. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by a processor, it implements the method as described in any one of claims 1 to 4.

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