Disclosure of Invention
The invention provides a panoramic overlay image spot rendering method, a geographic national condition monitoring method and a device, which are used for solving the defects that an overlay image based on a satellite photo in the prior art lacks stereoscopic impression and a common panoramic image does not have geographic information, and provide a display mode which is high in definition, rich in stereoscopic impression and accurately fused with geographic information elements for geographic national condition monitoring.
The invention provides a rendering method of a panoramic overlay image spot, which comprises the following steps:
acquiring a panoramic picture shot by an unmanned aerial vehicle;
acquiring geographic information of a shooting point of the unmanned aerial vehicle and spot information of an area where the unmanned aerial vehicle is located, wherein the spot information comprises the geometric shape of a spot and the geographic coordinates of each point on the spot;
converting the pattern spot information into a local coordinate system with the unmanned aerial vehicle shooting point as an origin to obtain pattern spot information under the local coordinate system;
and rendering the image spot information under the local coordinate system and the panoramic picture to obtain a panoramic picture rendering result of the superposed image spots.
According to the panoramic overlay image spot rendering method provided by the invention, before acquiring the geographic coordinates of the panoramic image shot by the unmanned aerial vehicle and the shooting point, the method comprises the following steps:
and setting the shooting point of the unmanned aerial vehicle and setting the initial shooting attitude of the unmanned aerial vehicle to face the same direction, wherein the local coordinate system takes east-sky-north as a coordinate axis.
According to the rendering method of the panoramic superposition image spots, provided by the invention, the image spot information comprises marking information.
According to the rendering method of the panoramic superposition image spots, provided by the invention, the image spot information under the local coordinate system comprises the geometric shape of the image spot under the local coordinate system and the local coordinates of each point on the image spot.
According to the panorama overlay image spot rendering method provided by the invention, the converting the image spot data into a local coordinate system with the unmanned aerial vehicle shooting point as an origin to obtain the image spot data under the local coordinate system comprises the following steps:
and dividing the pattern spots in the pattern spot data into a plurality of triangular surfaces, and converting the triangular surfaces into a local coordinate system with the unmanned aerial vehicle shooting point as an origin to obtain the pattern spot data under the local coordinate system.
The invention also provides a method for monitoring the geographical national conditions, which comprises the following steps:
obtaining a current panoramic picture and a historical panoramic picture shot by the unmanned aerial vehicle at the same shooting point, and obtaining adjacent panoramic pictures shot by the unmanned aerial vehicle at adjacent shooting points;
generating a current panoramic picture of the overlay image spots by adopting the rendering method of the panoramic overlay image spots, replacing the current panoramic picture in the current panoramic picture of the overlay image spots with the historical panoramic picture to obtain the historical panoramic picture of the overlay image spots, and replacing the current panoramic picture in the current panoramic picture of the overlay image spots with the adjacent panoramic picture to obtain the adjacent panoramic picture of the overlay image spots;
and monitoring the change of the image spot area in the current panoramic image of the superposed image spots and the historical panoramic image of the superposed image spots, and monitoring the change of the same image spot in the current panoramic image of the superposed image spots and the adjacent panoramic image of the superposed image spots to obtain a monitoring result.
The invention also provides a device for rendering the panoramic overlay image spots, which comprises:
the panoramic picture acquisition module is used for acquiring a panoramic picture shot by the unmanned aerial vehicle and geographic information of a shooting point of the unmanned aerial vehicle;
the image spot information acquisition module is used for acquiring image spot information of an area where the unmanned aerial vehicle shooting point is located, wherein the image spot information comprises the geometric shape of an image spot and the geographic coordinates of each point on the image spot;
the conversion module is used for converting the pattern spot information into a local coordinate system taking the unmanned aerial vehicle shooting point as an origin to obtain pattern spot information under the local coordinate system;
and the rendering module is used for rendering the image spot information under the local coordinate system and the panoramic picture to obtain the rendering effect of the panoramic picture with the image spots superposed.
The panorama superposition pattern spot rendering device further comprises a preprocessing module, wherein the preprocessing module is used for setting the unmanned aerial vehicle shooting point and setting the unmanned aerial vehicle initial shooting posture to face the same direction, and the local coordinate system takes east-sky-north as a coordinate axis.
The invention also provides a geographical national condition monitoring device, which comprises:
the acquisition module is used for acquiring a current panoramic picture and a historical panoramic picture shot by the unmanned aerial vehicle at the same shooting point and acquiring adjacent panoramic pictures shot by the unmanned aerial vehicle at adjacent shooting points;
a replacing module, configured to generate a current panoramic picture of the overlay patches by using the panoramic overlay patch rendering method, replace the current panoramic picture in the current panoramic picture of the overlay patches with the historical panoramic picture to obtain a historical panoramic picture of the overlay patches, and replace the current panoramic picture in the current panoramic picture of the overlay patches with the adjacent panoramic picture to obtain an adjacent panoramic picture of the overlay patches;
and the monitoring module is used for monitoring the change of the image spot area in the current panoramic picture of the superposed image spots and the historical panoramic picture of the superposed image spots, monitoring the change of the same image spot in the current panoramic picture of the superposed image spots and the adjacent panoramic picture of the superposed image spots and obtaining a monitoring result.
The invention also provides an electronic device, which comprises a memory, a processor and a computer program stored on the memory and capable of running on the processor, wherein the processor executes the program to realize the steps of any one of the panoramic overlay image spot rendering method and the geographic national condition monitoring method.
The present invention also provides a non-transitory computer readable storage medium having stored thereon a computer program which, when executed by a processor, implements the steps of the panorama overlay spot rendering method or the geographic national conditions monitoring method according to any one of the above.
The present invention also provides a computer program product comprising a computer program which, when executed by a processor, implements the steps of any of the above-mentioned panorama overlay spot rendering methods or the geographical national condition monitoring methods.
According to the panoramic overlay pattern spot rendering method, the geographic national condition monitoring method and the geographic national condition monitoring device, the geographic information related to the images is subjected to fusion display and comparison analysis by accurately controlling the unified processing of the aerial pose panoramic image and the geographic information coordinates. The geographical national condition monitoring provides a display mode which is high in definition, rich in stereoscopic impression and capable of accurately fusing geographical information elements.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the process of using satellite photo-based geographic national situation detection, limited to the resolution of satellite photos, many details cannot be obtained, and because satellite photos are taken looking down, stereoscopic perception is lacking. The common low-altitude aerial spliced panoramic picture can realize a picture with higher resolution and can provide strong stereoscopic impression. However, because the common panoramic image does not have accurate geographic information, the panoramic image cannot be fused and compared with actual GIS image spot data, and the fused display, comparison and analysis of the geographic information related to the image cannot be achieved.
For the advantages and disadvantages of the two data, as shown in fig. 1, an embodiment of the present invention provides a method for rendering a panorama overlay image spot, including:
step 101, acquiring a panoramic picture shot by an unmanned aerial vehicle;
102, acquiring geographic information of an unmanned aerial vehicle shooting point and pattern spot information of an area where the unmanned aerial vehicle shooting point is located, wherein the pattern spot information comprises a geometric shape of a pattern spot and geographic coordinates of each point on the pattern spot;
it should be noted that the tile information is a GIS tile which is one of the types of graphics that can be represented in the shape file format, that is, a polygon, and is generally a set of longitude and latitude coordinate values marked in GIS software.
Step 103, converting the pattern spot information into a local coordinate system with the unmanned aerial vehicle shooting point as an origin to obtain pattern spot information under the local coordinate system;
and 104, rendering the image spot information under the local coordinate system and the panoramic picture to obtain the panoramic picture with the image spots superposed.
It should be noted that the method can be combined with a recent low-altitude panoramic picture, and the recent low-altitude panoramic picture is superimposed in gis software to mark the spot information based on the satellite picture, so as to check the changes of water, soil, illegal construction and the like of the corresponding spot position.
According to the panorama superposition pattern spot rendering method, the connection between the panorama picture shot by the unmanned aerial vehicle and the pattern spot information near the unmanned aerial vehicle shooting point is established, and the pattern spot information is converted into the local coordinate system of the unmanned aerial vehicle shooting point, so that the pattern spot information which is originally presented in a plane has a three-dimensional expression form in the panorama picture. The panoramic picture with the superposed pattern spots has the advantages of high resolution and strong stereoscopic impression, and provides a new image presentation form fused with geographic information.
Compared with the prior art, the method has the advantages of low cost, high resolution of the picture and high timeliness. The method can be used for viewing the image spots in the panoramas which can be dragged and interacted and have a little stereoscopic impression, and can be used for viewing the image spots in a plurality of panoramas near the image spots, so that a more stereoscopic impression can be obtained. And the satellite icon in the traditional Gis software only has an overlooking visual angle and lacks stereoscopic impression.
In at least one embodiment of the present invention, before the obtaining of the geographic coordinates of the panoramic picture and the shooting point shot by the unmanned aerial vehicle, the method includes:
set up unmanned aerial vehicle shoots the point and set up unmanned aerial vehicle and shoot the gesture for the north orientation.
According to the panorama superposition pattern spot rendering method, the geographic information of the shooting point of the unmanned aerial vehicle can be obtained, the geographic information comprises longitude and latitude and height, and the initial shooting attitude of the unmanned aerial vehicle is set to face the same direction. In this way, the initial orientation of the spliced panoramic image is based on the first plane picture, and if the initial shooting posture of the unmanned aerial vehicle is uniform, the initial orientation of the finally spliced panoramic image is also uniform.
Preferably, set for unmanned aerial vehicle initial shooting gesture for heading the true north direction, it is more convenient to handle.
Before acquiring the panoramic picture, the shooting area needs to be segmented according to actual conditions, a shooting plan is made, and the longitude and latitude and the height of each panoramic picture shooting point are determined. According to the shooting plan, the unmanned aerial vehicle is automatically positioned to the position of a relevant shooting point by using relevant shooting software of the unmanned aerial vehicle, and shooting is always carried out by taking the north as the first shooting posture, so that the initial orientation of the generated panoramic image is ensured to be consistent geographically and to be in the north. And then carrying out panoramic stitching, grading, splitting and deployment on the aerial images shot by the unmanned aerial vehicle on the micro-scene platform to finally obtain the panoramic images convenient for Web end display.
It should be noted that the functions provided by the micro-scene platform may be panorama stitching: hugin, panorama hierarchical segmentation: krpano.
In at least one embodiment of the present invention, the local coordinate system has an east-heaven-north coordinate axis.
It should be noted that, a local coordinate system is provided with the panoramic image shooting point as the origin and east-sky-north as coordinate axes. The design can make the coordinate axis of the three-dimensional scene consistent with the actual coordinate axis, the processing is convenient, and no extra conversion is needed.
It should be noted that, the area where the unmanned aerial vehicle shooting point is located is a circular area with the shooting point geographic coordinate as a circle center and R as a radius, and R is preferably 300 meters.
In at least one embodiment of the present invention, the spot information includes annotation information.
It should be noted that the label information is generally added manually or generated in a clustering manner, and the label information is an attribute added by the spot according to actual business requirements, and is used for marking a date, an affiliated administrative area, a label area, a land type and the like. The annotation information in this embodiment generally includes the following fields:
1. rural industrial park reconstruction
The positions of the plants are marked by the pattern spots, and the pattern spots are regularly collected and matched, so that the dismantling condition can be followed.
2. Land change survey
The survey of agricultural land, industrial land, forest coverage and the like is carried out on natural resources every year and is recorded by means of pattern spots.
3. Law enforcement
And checking whether the violation exists.
4. Harmful species intrusion detection
5. Mineral resources, geological monitoring
Checking for the presence or absence of a particular topographical feature may create a risk, or acquisition problem.
In at least one embodiment of the present invention, the spot information in the local coordinate system includes a geometry of the spot in the local coordinate system and local coordinates of each point on the spot.
The geometric shape of the patches in the local coordinate system is a three-dimensional figure generated from the panoramic image.
In at least one embodiment of the present invention, the converting the speckle data into a local coordinate system with the unmanned aerial vehicle shooting point as an origin to obtain the speckle data in the local coordinate system includes:
and dividing the pattern spots in the pattern spot data into a plurality of triangular surfaces, and converting the triangular surfaces into a local coordinate system with the unmanned aerial vehicle shooting point as an origin to obtain the pattern spot data under the local coordinate system.
It should be noted that, in the coordinate transformation process, the WGS84 transitive gaussian-kruge projection is used, and in the embodiment of the present invention, the panorama rendering is performed first, and then the image spot is drawn on the panorama. Because the position information of the panoramic spot and the spot is converted into a local coordinate system from the same longitude and latitude high coordinate system, the relative positions of the panoramic spot and the spot are unchanged. The pattern spot can correctly reflect the actual situation in the whole view.
The embodiment of the invention also provides a geographic national condition monitoring method, which comprises the following steps:
step 201, obtaining a current panoramic picture and a historical panoramic picture shot by an unmanned aerial vehicle at the same shooting point, and obtaining adjacent panoramic pictures shot by the unmanned aerial vehicle at adjacent shooting points;
202, generating a current panoramic picture of the overlay image spots by adopting the panoramic overlay image spot rendering method, replacing the current panoramic picture in the current panoramic picture of the overlay image spots with the historical panoramic picture to obtain the historical panoramic picture of the overlay image spots, and replacing the current panoramic picture in the current panoramic picture of the overlay image spots with the adjacent panoramic picture to obtain the adjacent panoramic picture of the overlay image spots;
and 203, monitoring the change of the image spot areas in the current panoramic image of the superposed image spots and the historical panoramic image of the superposed image spots, monitoring the change of the same image spots in the current panoramic image of the superposed image spots and the adjacent panoramic image of the superposed image spots, and obtaining monitoring results.
According to the geographic national condition monitoring method provided by the embodiment of the invention, the change of buildings or landforms in the area corresponding to the image spots can be monitored by monitoring the change of the image spot area in the current panoramic image of the superimposed image spots and the historical panoramic image of the superimposed image spots, so that great convenience and accuracy are brought to the geographic national condition monitoring work.
The panorama overlay pattern rendering apparatus according to the present invention is described with reference to fig. 3, and the panorama overlay pattern rendering apparatus described below and the panorama overlay pattern rendering method described above may be referred to in correspondence with each other.
The embodiment of the invention also provides a device for rendering the panoramic overlay image spots, which comprises:
the panoramic picture acquisition module 301 is used for acquiring a panoramic picture shot by the unmanned aerial vehicle and geographic information of a shooting point of the unmanned aerial vehicle;
the pattern spot information acquisition module 302 is used for acquiring pattern spot information of an area where an unmanned aerial vehicle shooting point is located, wherein the pattern spot information comprises the geometric shape of a pattern spot and the geographic coordinates of each point on the pattern spot;
the conversion module 303 is configured to convert the pattern spot information into a local coordinate system using the unmanned aerial vehicle shooting point as an origin to obtain pattern spot information in the local coordinate system;
and the rendering module 304 is configured to render the speckle information in the local coordinate system and the panoramic picture to obtain a rendering effect of the panoramic picture with the speckle superimposed thereon.
According to the panorama superposition pattern spot rendering device provided by the embodiment of the invention, the connection between the panorama picture shot by the unmanned aerial vehicle and the pattern spot information near the unmanned aerial vehicle shooting point is established, and the pattern spot information is converted into the local coordinate system of the unmanned aerial vehicle shooting point, so that the pattern spot information which is originally presented in a plane has a three-dimensional expression form in the panorama picture. The panoramic picture with the superposed pattern spots has the advantages of high resolution and strong stereoscopic impression, and provides a new image presentation form fused with geographic information.
In at least one embodiment of the present invention, a preprocessing module 305 is further included for setting the drone shooting point and setting the drone shooting attitude to face the same direction, preferably the north direction.
In at least one embodiment of the present invention, the local coordinate system has an east-heaven-north coordinate axis.
In at least one embodiment of the present invention, the spot information includes annotation information.
The geographical national condition monitoring device provided by the present invention is described below with reference to fig. 4, and the geographical national condition monitoring device described below and the geographical national condition monitoring method described above may be referred to correspondingly.
The embodiment of the invention also provides a geographical national condition monitoring device, which comprises:
the acquisition module 401 is configured to obtain a current panoramic picture and a historical panoramic picture taken by the unmanned aerial vehicle at the same shooting point, and obtain adjacent panoramic pictures taken by the unmanned aerial vehicle at adjacent shooting points;
a replacing module 402, configured to generate a current panoramic picture of the overlay patches by using any one of the panoramic overlay patch rendering methods in the embodiments, replace a current panoramic picture in the current panoramic picture of the overlay patches with the historical panoramic picture to obtain a historical panoramic picture of the overlay patches, and replace a current panoramic picture in the current panoramic picture of the overlay patches with the adjacent panoramic picture to obtain an adjacent panoramic picture of the overlay patches;
a monitoring module 403, configured to monitor changes of the spot regions in the current panoramic picture of the overlay spot and the historical panoramic picture of the overlay spot, and monitor changes of the same spot in the current panoramic picture of the overlay spot and the adjacent panoramic picture of the overlay spot, so as to obtain a monitoring result.
The geographical national condition monitoring device provided by the embodiment of the invention can monitor the change of buildings or landforms in the area corresponding to the pattern spots by monitoring the change of the pattern spot area in the current panoramic picture of the superimposed pattern spots and the historical panoramic picture of the superimposed pattern spots, thereby bringing great convenience and accuracy to the geographical national condition monitoring work.
Fig. 5 illustrates a physical structure diagram of an electronic device, which may include, as shown in fig. 5: a processor (processor)510, a communication Interface (Communications Interface)520, a memory (memory)530 and a communication bus 540, wherein the processor 510, the communication Interface 520 and the memory 530 communicate with each other via the communication bus 540. Processor 510 may invoke logic instructions in memory 530 to perform the panorama overlay spot rendering method or the geographic national conditions monitoring method.
The rendering method of the panoramic overlay image spots comprises the following steps:
acquiring a panoramic picture shot by an unmanned aerial vehicle;
acquiring geographic information of a shooting point of the unmanned aerial vehicle and spot information of an area where the unmanned aerial vehicle is located, wherein the spot information comprises the geometric shape of a spot and the geographic coordinates of each point on the spot;
converting the pattern spot information into a local coordinate system with the unmanned aerial vehicle shooting point as an origin to obtain pattern spot information under the local coordinate system;
and rendering the image spot information under the local coordinate system and the panoramic picture to obtain a panoramic picture rendering result of the superposed image spots.
Therefore, the geographic national condition monitoring method comprises the following steps:
obtaining a current panoramic picture and a historical panoramic picture shot by the unmanned aerial vehicle at the same shooting point, and obtaining adjacent panoramic pictures shot by the unmanned aerial vehicle at adjacent shooting points;
generating a current panoramic picture of the overlay image spots by adopting the rendering method of the panoramic overlay image spots, replacing the current panoramic picture in the current panoramic picture of the overlay image spots with the historical panoramic picture to obtain the historical panoramic picture of the overlay image spots, and replacing the current panoramic picture in the current panoramic picture of the overlay image spots with the adjacent panoramic picture to obtain the adjacent panoramic picture of the overlay image spots;
and monitoring the change of the image spot area in the current panoramic image of the superposed image spots and the historical panoramic image of the superposed image spots, and monitoring the change of the same image spot in the current panoramic image of the superposed image spots and the adjacent panoramic image of the superposed image spots to obtain a monitoring result.
Furthermore, the logic instructions in the memory 530 may be implemented in the form of software functional units and stored in a computer readable storage medium when the software functional units are sold or used as independent products. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
In another aspect, the present invention further provides a computer program product, which includes a computer program, the computer program being stored on a non-transitory computer-readable storage medium, and when the computer program is executed by a processor, the computer is capable of executing the panorama overlay image spot rendering method or the geographic national condition monitoring method provided by the above methods.
The rendering method of the panoramic overlay image spots comprises the following steps:
acquiring a panoramic picture shot by an unmanned aerial vehicle;
acquiring geographic information of a shooting point of the unmanned aerial vehicle and spot information of an area where the unmanned aerial vehicle is located, wherein the spot information comprises the geometric shape of a spot and the geographic coordinates of each point on the spot;
converting the pattern spot information into a local coordinate system with the unmanned aerial vehicle shooting point as an origin to obtain pattern spot information under the local coordinate system;
and rendering the image spot information under the local coordinate system and the panoramic picture to obtain a panoramic picture rendering result of the superposed image spots.
Therefore, the geographic national condition monitoring method comprises the following steps:
obtaining a current panoramic picture and a historical panoramic picture shot by the unmanned aerial vehicle at the same shooting point, and obtaining adjacent panoramic pictures shot by the unmanned aerial vehicle at adjacent shooting points;
generating a current panoramic picture of the overlay image spots by adopting the rendering method of the panoramic overlay image spots, replacing the current panoramic picture in the current panoramic picture of the overlay image spots with the historical panoramic picture to obtain the historical panoramic picture of the overlay image spots, and replacing the current panoramic picture in the current panoramic picture of the overlay image spots with the adjacent panoramic picture to obtain the adjacent panoramic picture of the overlay image spots;
and monitoring the change of the image spot area in the current panoramic image of the superposed image spots and the historical panoramic image of the superposed image spots, and monitoring the change of the same image spot in the current panoramic image of the superposed image spots and the adjacent panoramic image of the superposed image spots to obtain a monitoring result.
In yet another aspect, the present invention further provides a non-transitory computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, is implemented to perform the panorama overlay spot rendering method or the geographic national situation monitoring method provided by the above methods.
The rendering method of the panoramic overlay image spots comprises the following steps:
acquiring a panoramic picture shot by an unmanned aerial vehicle;
acquiring geographic information of a shooting point of the unmanned aerial vehicle and spot information of an area where the unmanned aerial vehicle is located, wherein the spot information comprises the geometric shape of a spot and the geographic coordinates of each point on the spot;
converting the pattern spot information into a local coordinate system with the unmanned aerial vehicle shooting point as an origin to obtain pattern spot information under the local coordinate system;
and rendering the image spot information under the local coordinate system and the panoramic picture to obtain a panoramic picture rendering result of the superposed image spots.
Therefore, the geographic national condition monitoring method comprises the following steps:
obtaining a current panoramic picture and a historical panoramic picture shot by the unmanned aerial vehicle at the same shooting point, and obtaining adjacent panoramic pictures shot by the unmanned aerial vehicle at adjacent shooting points;
generating a current panoramic picture of the overlay image spots by adopting the rendering method of the panoramic overlay image spots, replacing the current panoramic picture in the current panoramic picture of the overlay image spots with the historical panoramic picture to obtain the historical panoramic picture of the overlay image spots, and replacing the current panoramic picture in the current panoramic picture of the overlay image spots with the adjacent panoramic picture to obtain the adjacent panoramic picture of the overlay image spots;
and monitoring the change of the image spot area in the current panoramic image of the superposed image spots and the historical panoramic image of the superposed image spots, and monitoring the change of the same image spot in the current panoramic image of the superposed image spots and the adjacent panoramic image of the superposed image spots to obtain a monitoring result.
The above-described embodiments of the apparatus are merely illustrative, and the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware. With this understanding in mind, the above-described technical solutions may be embodied in the form of a software product, which can be stored in a computer-readable storage medium such as ROM/RAM, magnetic disk, optical disk, etc., and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the methods described in the embodiments or some parts of the embodiments.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.