Intersection multi-target dynamic display and video linkage method, device and medium

Abstract

The invention provides an intersection multi-target dynamic display and video linkage method. The method comprises the following steps: constructing a three-dimensional map model of an intersection area; acquiring real-time data of traffic participants in the intersection area; the real-time data is preprocessed; mapping the preprocessed data into the three-dimensional map model to realize multi-target dynamic rendering and visual display; and based on a visual display result, identifying a traffic jam or an abnormal event, and triggering an early warning or unmanned aerial vehicle scheduling instruction. Through deep fusion and linkage of the three-dimensional scene and the real-time video, the problems of incomplete situation awareness and incomplete response mechanism in the prior art are solved, and the intelligent level and the emergency command capability of traffic management are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of intelligent transportation, in particular to a traffic situation awareness method based on multi-source data fusion and three-dimensional visualization technology, and specifically relates to a method and device for dynamically displaying multiple targets at an intersection based on a three-dimensional map and video linkage, and a medium. BACKGROUND

[0002] With the acceleration of urbanization, traffic flow has increased dramatically, and the traffic situation at intersection areas has become increasingly complex. Traditional traffic monitoring systems mainly rely on two-dimensional electronic maps and independent video monitoring cameras, which have many limitations. First, two-dimensional maps lack stereoscopic and spatial hierarchy and cannot intuitively display the spatial position relationship of traffic participants. Second, video monitoring systems and map platforms are independent of each other, and there is a lack of effective fusion and linkage between data, making it difficult for managers to form a unified situation awareness by switching between different systems. Third, existing systems usually lack intelligent traffic state (such as congestion) automatic identification and early warning functions. Finally, for sudden events such as traffic accidents, there is a lack of quick and proactive emergency response means, such as using drones to provide high-altitude perspectives.

[0003] Although drones and three-dimensional map technology have been applied in individual fields, the deep integration of these technologies to achieve a full-link automated system from data collection, processing, visualization to intelligent early warning and drone linkage scheduling is still a technical problem that needs to be solved in the current field of intelligent transportation.

[0004] Therefore, there is an urgent need for an integrated solution that can integrate multi-source data, dynamically display traffic flow in three-dimensional space, and link with video and drones, in order to improve the perception, analysis, and intervention capabilities of the traffic situation at intersections. SUMMARY

[0005] The present application aims to solve at least one of the technical problems existing in the prior art mentioned above, and proposes a method and device for dynamically displaying multiple targets at an intersection based on a three-dimensional map and video linkage, in order to achieve comprehensive, three-dimensional, and intelligent regulation of the traffic situation at intersections.

[0006] In a first aspect, the embodiments of the present application provide a method for dynamically displaying multiple targets at an intersection and video linkage, comprising:

[0007] constructing a three-dimensional map model of the intersection area;

[0008] acquiring real-time data of traffic participants in the intersection area;

[0009] preprocessing the real-time data;

[0010] Map the pre-processed data into the three-dimensional map model to achieve multi-target dynamic rendering and visual display.

[0011] Based on the results of the visual display, identify traffic congestion or abnormal events and trigger early warning or UAV dispatch instructions.

[0012] Further, the real-time data is pre-processed, including:

[0013] Convert the collected GPS latitude and longitude coordinates to the three-dimensional map local coordinate system, and use Kalman filtering or particle filtering algorithm to smooth the target position.

[0014] Further, the real-time data is pre-processed, including:

[0015] Timestamp embedding and frame rate uniform processing are performed on the acquired video stream to realize the spatio-temporal synchronization of video and three-dimensional map model.

[0016] Further, traffic congestion identification is based on target density, speed change and / or historical traffic data, and trend prediction is performed through LSTM model.

[0017] Further, after triggering the UAV dispatch instruction, the UAV flies to the event site to shoot video and returns to the three-dimensional map model for superimposed display.

[0018] Further, different congestion levels in the three-dimensional map model are visually distinguished by different colors.

[0019] Further, it also includes:

[0020] Support user interaction operations, including one or more of multi-view switching, target query and video linkage playback.

[0021] Further, the method is applicable to one or more of intelligent traffic command center, automatic driving test environment or smart city management platform.

[0022] In a second aspect, the embodiments of the present application provide an electronic device, comprising: one or more processors;

[0023] Memory for storing one or more programs; when the one or more programs are executed by the one or more processors, the one or more processors can implement the steps in the method of any of the preceding aspects.

[0024] In a third aspect, the embodiments of the present application provide a computer readable medium, the computer readable medium stores a computer program, and the computer program is executed by a processor to implement the steps in the method of any of the preceding aspects.

[0025] The application provides a kind of intersection multi-target dynamic display and video linkage method, through the depth fusion and linkage of three-dimensional scene and real-time video, the problem of incomplete situation awareness and imperfect response mechanism in the prior art is solved, and the intelligent level of traffic management and emergency command ability are significantly improved. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 A core process block diagram of a kind of intersection multi-target dynamic display and video linkage method based on three-dimensional map provided for the embodiment of the application;

[0027] Figure 2 A business process chart of a kind of intersection multi-target dynamic display and video linkage method based on three-dimensional map provided for the embodiment of the application;

[0028] Figure 3 The structural block diagram of a kind of electronic equipment provided for the embodiment of the application. DETAILED DESCRIPTION

[0029] To make those skilled in the art better understand the technical solutions of the present application, the exemplary embodiments of the present application are described below in conjunction with the drawings, including various details of the embodiments of the present application to help understanding, which should be considered only as exemplary. Therefore, those of ordinary skill in the art should realize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present application. Similarly, for the sake of clarity and conciseness, the description in the following description omits the description of well-known functions and structures. In the case of no conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

[0030] The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. The terms used herein are only used to describe specific embodiments and are not intended to limit the present application. As used herein, the singular forms "a" and "the" are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that when the terms "comprise" and / or "consist of" are used in the specification, the specified features, integers, steps, operations, elements, and / or components are present, but one or more other features, integers, steps, operations, elements, components, and / or groups thereof can be present or added. The terms "connected" or "coupled" and similar terms are not limited to physical or mechanical connections or couplings, but can include electrical connections, whether direct or indirect.

[0031] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present application, and will not be interpreted in an overly literal or overly formal sense unless expressly so defined herein.

[0032] As urban traffic complexity continues to rise, traditional traffic monitoring methods such as two-dimensional maps and independent video surveillance have been difficult to meet the comprehensive perception needs of traffic situation at intersections. The defects of the prior art include:

[0033] 1. Lack of spatial and video data fusion mechanism: Most three-dimensional map platforms only display structured models and are not combined with real video images, so users cannot obtain complete on-site perception.

[0034] 2. Multi-target recognition and modeling are isolated from video surveillance systems: Data collected by various sensors are usually processed separately and are not synchronized in time and space with video resources.

[0035] 3. Traffic congestion identification and visualization are missing: Existing systems lack automatic identification and intuitive display functions for traffic congestion status.

[0036] 4. The response mechanism for sudden events is not perfect: In the face of traffic accidents, abnormal behavior and other sudden conditions, there is a lack of rapid dispatch and remote intervention means.

[0037] 5. UAV linkage application has not been popularized: Although UAVs have been tried in traffic management, their deep integration with three-dimensional map systems is still in the exploratory stage.

[0038] Therefore, there is an urgent need for a technical solution that can realize multi-target dynamic display at intersections, traffic congestion identification, early warning event pushing and UAV linkage control in a three-dimensional map to comprehensively improve traffic situation perception and emergency management capabilities.

[0039] Reference Figure 1 and Figure 2 One embodiment of the present application provides a three-dimensional map-based multi-target dynamic display and video linkage method for intersections, which can specifically include the following steps.

[0040] Step 1, constructing a three-dimensional map model of the intersection area, the three-dimensional map model including road structures, traffic facilities and dynamic traffic participants.

[0041] Specifically, the scene of the intersection area is completely modeled and reproduced in three dimensions, including road markings, traffic lights, sidewalks, street trees, bus stops, and signs, etc., to achieve modeling of the intersection area in proportion. At the same time, the traffic participants in the intersection area are dynamically rendered in the map in the form of three-dimensional models.

[0042] Step 2, obtaining real-time data of traffic participants in the intersection area.

[0043] Specifically, the real-time data of the positions, types, heading angles, and speeds of the traffic participants in the intersection area are obtained through front-end devices such as cameras, radars, and edge computing units. At the same time, the data is processed to identify the static state of the object.

[0044] More specifically, the camera is used to capture vehicle images, the radar is used to detect vehicle distance and speed, and the edge computing unit is used for preliminary target recognition and data fusion. The fusion of such multi-source data can improve the comprehensiveness and reliability of data acquisition.

[0045] Step 3, preprocessing the real-time data.

[0046] Specifically, the original real-time data collected is filtered, denoised, coordinate converted, target recognized and classified. Video stream is preprocessed by format unification, frame rate adjustment, and timestamp embedding, etc.

[0047] The collected GPS latitude and longitude coordinates are converted to the local coordinate system of the three-dimensional map, and Kalman filtering or particle filtering algorithm is used to smooth the target position to reduce sensor error. More specifically, the GPS coordinates (116.4°, 39.9°) of a vehicle are converted to (x, y, z) coordinates in the three-dimensional map, and Kalman filtering is used to reduce positioning jitter. Such settings can improve the stability and accuracy of target position display.

[0048] The acquired video stream is processed by timestamp embedding and frame rate unification to achieve spatio-temporal synchronization of video and three-dimensional map model. That is, based on the timestamp matching video frame and three-dimensional map model state, spatial projection mapping is realized to ensure that the video picture and three-dimensional map model position are consistent, achieving spatio-temporal synchronization effect. More specifically, the UTC timestamp of each frame of the video stream obtained by the camera is embedded, and the timestamp of the target state in the three-dimensional map model is matched to realize video and model synchronous playback. Such settings can enhance the consistency of video and three-dimensional scene, improve user experience and decision accuracy.

[0049] Step 4, mapping the preprocessed data to the three-dimensional map model to realize multi-target dynamic rendering and visual display.

[0050] Specifically, the pre-processed video stream is time and spatially aligned with the target position in the three-dimensional map model, and the video screen is played synchronously on the three-dimensional map interface of the three-dimensional map model. According to the target type, the target information is mapped into the three-dimensional map engine, and the target position, direction, state and other attributes are updated in real time, and the congestion state is displayed by color. Different congestion degrees in the three-dimensional map model are visually distinguished by different colors. For example, green represents smooth, yellow represents slow, red represents congestion, and dark red represents serious congestion. Such a setting can intuitively display the traffic state, facilitating quick decision-making by management personnel.

[0051] Step 5, based on the result of the visualization display, identifying traffic congestion or abnormal events and triggering early warning or unmanned aerial vehicle dispatch instructions.

[0052] Specifically, traffic congestion identification is based on target density, speed change and / or historical traffic data, and traffic congestion development trend prediction is performed through an LSTM model. More specifically, the original data is pre-processed to form a time series format suitable for LSTM input; a neural network containing two layers of LSTM units is constructed, each layer having 50 memory cells; during the training phase, the past one hour of data is used as input to predict the average vehicle speed for the next half hour; after multiple iterations of training, the model's effectiveness is verified on the test set to ensure that it can effectively predict the development trend of traffic congestion. More specifically, the past one hour of vehicle speed data is used to train the LSTM model to predict the average vehicle speed for the next half hour, and if it is below a predetermined threshold, it is determined to be congested. Such a setting can achieve intelligent identification and early warning of traffic congestion.

[0053] When serious congestion, accidents or abnormal behavior are detected, unmanned aerial vehicle dispatch instructions are automatically triggered, and the unmanned aerial vehicle flies to the incident location, takes high-altitude perspective video and returns it, and the unmanned aerial vehicle video screen is superimposed in the three-dimensional map interface to assist command and decision-making. Specifically, when a traffic accident is detected, the system automatically dispatches an unmanned aerial vehicle to the scene, takes video and returns it in real time, and displays the unmanned aerial vehicle perspective in the three-dimensional map. Such a setting can enhance the remote sensing and emergency command capabilities for sudden events.

[0054] Abnormal events include at least one of running a red light, going against the flow, and abnormal staying. Running a red light, going against the flow, and abnormal staying are identified in combination with video and three-dimensional map model information, and an alarm is triggered and pushed to management personnel. Specifically, a vehicle is identified by video analysis as crossing the stop line under a red light, and the system automatically triggers a reverse direction alarm. Such a setting can improve the automatic identification and response capability of traffic violations.

[0055] Preferably, the intersection multi-target dynamic display and video linkage method provided in the application can also include supporting user interactive operations, including one or more of multi-view switching, target query, and video linkage playback. Specifically, the user can call up the real-time video of a certain vehicle in the three-dimensional map model by clicking on it, and play it. Such a setting can improve the interactivity and practicality of the system.

[0056] Preferably, the intersection multi-target dynamic display and video linkage method provided in the application is applicable to one or more of intelligent traffic command centers, automatic driving test environments, or smart city management platforms. Specifically, the system can be deployed in a certain smart city project for real-time monitoring of major intersection traffic conditions and emergency response. The application has good scalability and application prospects, and is suitable for various intelligent traffic scenarios.

[0057] In a specific embodiment, a city main road intersection is taken as the application scenario. First, a three-dimensional real scene model with centimeter-level precision of the intersection is constructed using unmanned aerial vehicle oblique photography and laser scanning technology. High-definition network cameras, millimeter wave radars, and edge computing servers are deployed in each direction of the intersection.

[0058] When the system is running, the cameras and radars continuously capture intersection vehicle information. The edge computing unit analyzes the video stream in real time, identifies vehicles, license plates, speeds, and directions, and packages the data for uploading to the central server. After receiving the data, the server performs Kalman filtering to smooth the trajectory and converts the coordinates in the world coordinate system to the local coordinate system of the three-dimensional map.

[0059] The three-dimensional engine (such as Unity3D or Cesium) receives data every 100 milliseconds, driving the corresponding vehicle model to move in the three-dimensional scene. At the same time, the system calculates the average speed of each lane. When the average speed of a certain lane is lower than 15 kilometers per hour and lasts for more than 2 minutes, the system renders the lane in red (congestion state) and pops up a prompt box on the monitoring large screen.

[0060] At this time, the on-duty personnel can call up the real-time video of the vehicle in the congested area of the three-dimensional model when it passed through the intersection to trace back and determine the cause of the congestion.

[0061] Compared with the prior art, in general, the intersection multi-target dynamic display and video linkage method provided in the application has the following significant advantages:

[0062] 1. Immersive situational awareness: By combining three-dimensional maps with real-time data, a more intuitive and three-dimensional traffic situation display is provided, overcoming the limitations of two-dimensional maps.

[0063] 2. Deep fusion of multi-source data: It realizes the fusion and linkage of video streams, radar point clouds and location information under a unified spatiotemporal benchmark, which improves the accuracy and value of the data.

[0064] 3. Intelligent proactive early warning: The algorithm model automatically identifies congestion and abnormal events, transforming passive monitoring into proactive discovery and improving management efficiency.

[0065] 4. Highly efficient emergency response: The introduction of drones as highly mobile high-altitude sensing units and automated scheduling processes greatly enhance the system's ability to respond quickly to emergencies and remotely command them.

[0066] 5. Excellent scalability and practicality: The system has a clear architecture and modular design, which can be applied to urban traffic command centers as well as provide support for autonomous driving testing and smart city construction.

[0067] Based on the same inventive concept, embodiments of this application also provide an electronic device. Figure 3 This is a structural block diagram of an electronic device provided in an embodiment of this application. Figure 3 As shown in the embodiments of this application, an electronic device includes: one or more processors 101, a memory 102, and one or more I / O interfaces 103. The memory 102 stores one or more programs, which, when executed by the one or more processors, enable the one or more processors to implement any of the multi-target dynamic display and video linkage methods at intersections as described in the above embodiments; the one or more I / O interfaces 103 are connected between the processor and the memory, configured to enable information interaction between the processor and the memory.

[0068] The processor 101 is a device with data processing capabilities, including but not limited to a central processing unit (CPU); the memory 102 is a device with data storage capabilities, including but not limited to random access memory (RAM, more specifically SDRAM, DDR, etc.), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), and flash memory (FLASH); the I / O interface (read / write interface) 103 is connected between the processor 101 and the memory 102, and can realize information interaction between the processor 101 and the memory 102, including but not limited to a data bus (Bus).

[0069] In some embodiments, the processor 101, memory 102, and I / O interface 103 are interconnected via bus 104, and thus connected to other components of the computing device.

[0070] In some embodiments, the one or more processors 101 include a field-programmable gate array.

[0071] The embodiment of the present application further provides a computer readable medium. The computer readable medium stores a computer program, and the program is executed by a processor to implement the steps in the intersection multi-target dynamic display and video linkage method according to any one of the above embodiments. The computer readable storage medium can be a volatile or non-volatile computer readable storage medium.

[0072] The embodiment of the present application further provides a computer program product, including computer readable code or a non-volatile computer readable storage medium carrying computer readable code, when the computer readable code is run in a processor of an electronic device, the processor in the electronic device executes the intersection multi-target dynamic display and video linkage method.

[0073] Those skilled in the art can understand that all or some of the steps in the above disclosed method, the functions of the modules / units in the system and the device can be implemented as software, firmware, hardware and appropriate combinations thereof. In the hardware implementation, the division between the functional modules / units mentioned in the above description does not necessarily correspond to the division of physical components; for example, one physical component can have multiple functions, or one function or step can be performed by several physical components in cooperation. Some or all of the physical components can be implemented as software executed by a processor, such as a central processing unit, a digital signal processor or a microprocessor, or as hardware, or as an integrated circuit, such as an application specific integrated circuit. Such software can be distributed on a computer readable storage medium, which can include computer storage media (or non-transitory media) and communication media (or transitory media).

[0074] As known to those skilled in the art, the term computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable program instructions, data structures, program modules or other data. Computer storage media includes, but is not limited to, random access memory (RAM), read only memory (ROM), erasable programmable read only memory (EPROM), static random access memory (SRAM), flash memory or other memory technology, portable compact disc read only memory (CD-ROM), digital versatile disc (DVD) or other optical disk storage, magnetic cassettes, magnetic tapes, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store the desired information and can be accessed by a computer. In addition, it is known to those skilled in the art that communication media generally includes computer readable program instructions, data structures, program modules or other data in modulated data signals such as carrier waves or other transmission mechanisms, and can include any information delivery medium.

[0075] The computer readable program instructions described herein can be downloaded to respective computing / processing devices from a computer readable storage medium or to an external computer or external storage device via a network, for example, the Internet, a local area network, a wide area network and / or a wireless network. The network can comprise copper transmission cables, optical transmission fibers, wireless transmission, routers, firewalls, switches, gateway computers and / or edge servers. A network adapter card or network interface in each computing / processing device receives computer readable program instructions from the network and forwards the computer readable program instructions for storage in a computer readable storage medium within the respective computing / processing device.

[0076] Computer readable program instructions for carrying out operations of the present application can be assembler instructions, instruction-set-architecture (ISA) instructions, machine instructions, machine dependent instructions, microcode, firmware instructions, state-setting data, or either source code or object code written in any combination of one or more programming languages, including an object oriented programming language such as Smalltalk, C++ or the like, and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The computer readable program instructions can execute entirely on the user's computing / processing device, partly on the user's computing / processing device, as a stand-alone software package, partly on the user's computing / processing device and partly on a remote computing / processing device or entirely on the remote computing / processing device or server. In the latter scenario, the remote computing / processing device can be connected to the user's computing / processing device through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection can be made to an external computing / processing device, for example, through the Internet using an Internet Service Provider. In some embodiments, electronic circuitry including, for example, programmable logic circuitry, field-programmable gate array (FPGA), or programmable logic array (PLA) can execute the computer readable program instructions by utilizing state information of the computer readable program instructions to personalize the electronic circuitry, in order to perform aspects of the present application.

[0077] The computer program product described herein can be embodied in a tangible computer readable storage medium, or embodied in a software product, such as a software development kit (SDK), and the like.

[0078] The computer program product described herein can be embodied in a tangible computer readable storage medium, or embodied in a software product, such as a software development kit (SDK), and the like.

[0079] These computer readable program instructions can be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks. These computer readable program instructions can also be stored in a computer readable storage medium that can include a non-transitory computer readable storage medium that can be a computer- readable storage medium having no data storage cycles that change state. The instructions can be executed by one or more processors of a computer, to cause a series of operational elements or steps to be performed on the computer to produce a computer implemented process; such that the instructions, which execute via one or more computer program product, implement a computer implemented process for performing the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0080] The computer readable program instructions can also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational elements or steps to be performed on the computer, other programmable data processing apparatus, or other device to produce a computer implemented process such that the instructions which execute on the computer or other programmable data processing apparatus implement the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0081] The computer readable program instructions can also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational elements or steps to be performed on the computer, other programmable data processing apparatus, or other device to produce a computer implemented process such that the instructions which execute on the computer or other programmable data processing apparatus implement the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0082] Example embodiments have been disclosed herein and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation. In some embodiments, it will be apparent to one of ordinary skill in the art that features, characteristics, or elements described with reference to a specific embodiment can be used alone or in combination with other embodiments unless expressly stated otherwise. Accordingly, one of ordinary skill in the art will recognize that the disclosure is not limited to the embodiments described herein, but can be practiced with determination by one of ordinary skill in the art with the benefits of the disclosure in view.

Claims

1. A method for dynamic display and video linkage of multiple targets at intersections, characterized in that, The method comprises: constructing a three-dimensional map model of the intersection area; acquiring real-time data of traffic participants in the intersection area; preprocessing the real-time data; mapping the preprocessed data into the three-dimensional map model to realize multi-target dynamic rendering and visual display; based on the result of the visual display, identifying traffic congestion or abnormal events and triggering early warning or unmanned aerial vehicle scheduling instructions.

2. The method of claim 1, wherein, The preprocessing of the real-time data comprises: converting the collected GPS latitude and longitude coordinates to a three-dimensional map local coordinate system and using Kalman filtering or particle filtering algorithm to smooth the target position.

3. The method of claim 1, wherein, The preprocessing of the real-time data comprises: performing timestamp embedding and frame rate uniform processing on the acquired video stream to realize the spatiotemporal synchronization of the video and the three-dimensional map model.

4. The method of claim 1, wherein, The traffic congestion identification is based on target density, speed change and / or historical traffic data, and the trend is predicted through an LSTM model.

5. The method of claim 1, wherein, After triggering the unmanned aerial vehicle scheduling instruction, the unmanned aerial vehicle flies to the event site to take a video and returns it to the three-dimensional map model for superimposed display.

6. The method of claim 1, wherein, Different congestion levels in the three-dimensional map model are visually distinguished by different colors.

7. The method of claim 1, wherein, Further comprising: supporting user interaction operations, including one or more of multi-view switching, target query and video linkage playback.

8. The method of claim 1, wherein, The method is applicable to one or more of an intelligent traffic control center, an automatic driving test environment or a smart city management platform.

9. An electronic device, comprising: The method comprises: one or more processors; a memory for storing one or more programs; when the one or more programs are executed by the one or more processors, the one or more processors can realize the steps in the method of any one of claims 1 to 8.

10. A computer readable medium having stored thereon a computer program, characterized in that The computer program, when executed by a processor, can realize the steps in the method of any one of claims 1 to 8.

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