CN101576926B - Monitor video searching method based on geographic information system - Google Patents

Abstract

The invention discloses a monitor video searching method based on a geographic information system, which comprises the following steps of: recording the range of monitoring area which can be displayedon GIS in the shot target area of a monitoring camera when the monitoring camera shoots a video; establishing a corresponding relation between a monitoring video clip and the range of monitored targe t area thereby; and according to the corresponding relation, searching the video of the monitoring area which covers the searching target area. According to the geographic position information, angle information and magnification information of the camera shooting the monitoring video, the method calculates the monitoring area of the shot video. The method monitors the change of parameters of the PTZ camera such as position, angle and the like, and stores the record of the change of the parameters so as to accurately present the change of monitoring range of the camera again in a certain time interval when needed.

Description

A Surveillance Video Retrieval Method Based on Geographic Information System

technical field

The invention relates to video retrieval technology, in particular to a monitoring video retrieval method based on a geographic information system.

Background technique

Video surveillance system is an important part of security engineering. It is widely used in many occasions because it can provide intuitive, convenient and rich information. In recent years, with the popularization of broadband, the development of computer technology, and the improvement of image processing technology, video surveillance is being more and more widely used in many fields. The basic business function of video surveillance is to provide means of real-time monitoring of target occasions or target objects, and to record and store the monitored pictures for later playback. In modern surveillance systems, PTZ cameras are the main equipment for real-time video surveillance and video recording. It is mainly composed of a camera responsible for video collection and a supporting pan/tilt responsible for installing and fixing the camera. The PTZ is suitable for scanning and monitoring in a large area, and it can expand the monitoring range of the camera. Its high-speed rotation is realized by the motor on the pan-tilt, and the precise rotation and positioning of the motor is controlled by sending a specific format control signal to the pan-tilt device.

The video surveillance system generally operates 24 hours a day, and regularly records video according to the video storage plan, and can also be triggered manually or by an alarm.

At present, video retrieval in the monitoring system mainly relies on manual operations, which is cumbersome and time-consuming. The modern video retrieval technology can be divided into two categories from the formal point of view: one is based on text (keyword) retrieval, its retrieval efficiency depends on the text description of the video, the difficulty lies in how to accurately and comprehensively describe the video; Content-based retrieval is to retrieve video data in a large-scale video database according to the content and context of the video. It automatically extracts and describes the features and content of videos without human involvement. Its advantage is that it can be retrieved by automatically extracting audio-visual features, but its difficulty lies in how to calculate the similarity, and it is difficult for users to find suitable examples. The essence of these retrieval technologies is to add tags containing retrieval target information to videos or video clips. The difference is whether these tags are added manually or automatically by a computer after relevant analysis.

The method of face-to-face video retrieval in the video surveillance system is mainly to search one by one through the device that stores the video. Since the pan/tilt is rotating, the area it monitors is constantly changing. Therefore, video recordings record video information at different times and in different regions. If you want to find the video information of a certain characteristic area, for example, you want to find the video information of a certain corner of the square in the past ten hours, and the surveillance camera can only monitor this corner in part of the time, then you need to find out All the videos recorded by the camera in the past ten hours, and the video clips related to the corner area were found by manual observation.

Therefore need a kind of fast video retrieval method, can find out the video of interested area in the video recording of different monitoring areas recorded by the rotating pan-tilt camera.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art, and provide a monitoring video retrieval method based on a geographic information system.

The surveillance video retrieval method based on geographic information system comprises the following steps:

1) Obtain the geographic location, installation height, and angle correction value information of the PTZ camera on the geographic information system;

2) When the PTZ command of the PTZ camera is issued, the content of a PTZ command is sent to the monitoring module at the same time. After the monitoring module detects that the PTZ command is issued, it judges that the PTZ command affects the video captured by the PTZ camera. The impact of the monitoring area range, and obtain the relevant information of the pan/tilt after the execution of the command that affects the monitoring area of the pan/tilt. The relevant information refers to the horizontal and vertical angle information of the camera, the CCD magnification when shooting, and the above The PTZ event where the parameters change, the issuing and execution of a PTZ command is called a PTZ event;

3) Generate the geographical time tag of the PTZ camera according to the obtained relevant parameters;

4) Recording the geographical time tags in order, and mapping them to the video clips according to the corresponding relationship in time;

5) When carrying out video retrieval, take out the relevant information that can represent the video monitoring area in the geographic time tag, calculate the monitoring range of the PTZ camera on the GIS;

6) Match the geographical area reflected by the geographical time tag with the retrieved target area, and find out the video recordings in the time period corresponding to the geographical time tag covering the searched area.

The described step of generating the geographic time tag of the PTZ camera according to the relevant parameters obtained:

1) Fill in the end time of the last geographic time tag of the PTZ camera, calculate and refill the relevant information of the previous geographic time tag, so that the angle information and CCD magnification information during shooting can accurately reflect the geographical time tag The angle information and CCD magnification of the PTZ camera at the end moment;

2) Generate a new geographic time tag and fill in the start time;

3) According to the PTZ event that causes the geographic time tag to be generated, fill in different content of the geographic time tag for different PTZ events.

The steps of recording the geographical time tags in order and mapping them to the video clips according to the corresponding relationship in time are as follows:

1) Obtain the start time of the video clip, the end time, and the PTZ camera for shooting the video;

2) Find all geographical time tags of the PTZ camera, find out the geographical time tags whose time period overlaps with the time period of the video clip;

3) Corresponding the found geographic time tag set to the video segment.

When the described video retrieval is carried out, take out the related information of the cloud platform in the geographic time tag, and calculate the monitoring range steps of the cloud platform camera on the geographic information system:

1) According to the relevant information of the PTZ in the geographical time tag, establish the quadrangular pyramid of the viewing area of the PTZ camera on the GIS, and the trapezoidal intersection of the quadrangular pyramid of the viewing area and the geographic plane of the map is the two-dimensional visible area of the PTZ on the map the projection;

2) Calculate the geometric parameters of the trapezoidal intersection between the quadrangular pyramid of view and the geographical plane of the map according to the relevant information of the PTZ in the geographical time tag. The shape of the trapezoidal intersection is determined by the height of the PTZ and the vertical angle of the PTZ. The size of the surface is determined by the CCD magnification of the gimbal, and the position of the trapezoidal intersection is determined by the horizontal rotation angle of the gimbal.

The described geographic area reflected by the geographical time tag is matched with the retrieved target area, and the video recording steps in the time period corresponding to the geographical time tag covering the searched area are found:

1) The regions calculated according to the geographic time tags in the geographic time tag set corresponding to the video clip are sequentially matched with the graphics of the retrieved target area on the geographic information system;

2) Find out the geographical time label of the region where the two graphics overlap;

3) Take out the video clips within the start and end time of these geographic time tags, combine them in chronological order, and present them as query results.

The invention connects the monitoring video record with the monitored geographical area range, and can conveniently realize the video search according to the monitored area of the video content. Instead of time-consuming and labor-intensive searches through manual methods.

Description of drawings

Fig. 1 is the flowchart of the surveillance video retrieval method based on geographic information system;

FIG. 2 is a schematic diagram of a monitoring area of a pan-tilt camera according to an embodiment of the present invention.

Detailed ways

The surveillance video retrieval method based on geographic information system comprises the following steps:

1) Obtain the geographical location, installation height, and angle correction value information of the PTZ camera on the geographic information system. The PTZ camera is an object in the geographic information system. The above information needs to be manually collected and input into the geographic information system. take out.

2) When the PTZ command of the PTZ camera is issued, the content of a PTZ command is sent to the monitoring module at the same time. After the monitoring module detects that the PTZ command is issued, it judges that the PTZ command affects the video captured by the PTZ camera. The impact of the range of the monitoring area, if the gimbal command is preset switch, preset cruise, speed change, gimbal turn left, gimbal turn right, gimbal turn up, gimbal turn down, then get the right The relevant information of the PTZ after the command that affects the monitoring area of the PTZ is executed. The relevant information refers to the horizontal and vertical angle information of the camera, the CCD magnification when shooting, and the PTZ events that cause the above parameters to change. A cloud The release and execution of platform commands are called PTZ events;

3) Generating the geographical time tag of the PTZ camera according to the obtained relevant parameters; a data record used to reflect the relevant parameters of the PTZ camera within a certain period of time is called a PTZ geographic time tag. It is used to indicate the static monitoring area of the PTZ camera or the dynamic change of the monitoring area of the PTZ camera within a certain period of time. Geographic time tags can be represented using the table PtzGeoIndex. Its main fields include the ID of the PTZ device, the time of entering the area, the time of leaving the area, the horizontal angle of the PTZ camera, the vertical angle of the PTZ camera, the horizontal speed and vertical direction of the PTZ within this period The rotation speed of the PTZ camera, the CCD magnification of the PTZ camera, the geographic coordinate position of the PTZ camera in the GIS, and the PTZ event type that generated this tag.

According to the seven types of PTZ commands that may affect the monitoring area of the PTZ camera, it is divided into the following seven types of PTZ events:

Preset switching event---corresponding to the switch of the PTZ camera from any other position to the position set by the target preset position. This event will cause a new PTZ geographic time tag to be generated. Because the event is considered to happen instantaneously, the time when the tag enters the area is filled in the current system time of the server when the event notification is received from the PTZ command monitoring module, and the time when the event leaves the area will be in the next PTZ Filled in when the event occurs. The pan/tilt horizontal angle and pan/tilt vertical angle of this label are the horizontal angle and vertical angle of the preset position. The horizontal rotation speed and vertical rotation speed of the gimbal are meaningless to calculate the geographical range of the tag for this type of event, but for the inheritance of this information, set it as the same as a gimbal geographic time tag on the gimbal camera same value. If the PTZ geographical time tag is the first record of the PTZ camera in the database, then the server directly requests the PTZ camera device or the PTZ control center to obtain this value.

The preset position cruise event can be regarded as a collection of multiple preset position switching events, and is not listed as a single type of event. When the PTZ cruise command is issued, it can be decomposed into multiple preset position switching events, so as to realize the recording of the PTZ geographic time tag.

PTZ left, right, up, down events. These four events share great similarities. Corresponding to the left turn, turn right, turn up, and turn down commands issued to the PTZ camera. These four events are not completed instantaneously, and the time when the PTZ geographical time tag generated by it enters the area is the current system time when the event notification is received from the PTZ command monitoring module, and the time of leaving the area will be here Fill in when the next required event of this type of event - PTZ stop event occurs, that is, fill in the current system time when the stop event occurs. The horizontal angle and vertical angle information of the PTZ camera in this tag is filled in as the horizontal and vertical angle values of the PTZ at the end of the event, which are also filled in the PTZ stop event. When the event occurs, the horizontal rotation speed and vertical rotation speed of the gimbal will inherit the same value from a gimbal geographic time tag on the gimbal camera. If the PTZ geographic time tag is the first record of the PTZ camera in the database, then the server directly requests the PTZ camera device or the PTZ control center to obtain this value. The geographic range represented by the PTZ geographic time tag generated by such events is a dynamically changing area. When calculating the area, the continuously changing area can be calculated according to the event duration, event type, speed and other information.

PTZ stop event. Corresponding to the user's order to stop the rotation of the PTZ camera. There must be a gimbal stop event after the gimbal rotation event ends. A single PTZ stop event will not affect the monitoring area of the PTZ camera, so only the PTZ stop event following the above PTZ rotation event will be processed. For this event, first fill in the relevant fields of the previous PTZ geographic time tag. Including filling in the end time of the previous PTZ geographic time tag, and the horizontal and vertical angles at the end of the calculation. Then generate a new geographic tag, fill in the current time as the start time, and fill in the end time when the next event occurs. The event type is PTZ stop event, and the other fields are exactly the same as those in the previous tab.

The PTZ speed change event corresponds to the command issued by the user to change the rotation speed of the PTZ camera. After listening to the instruction, the designated monitoring module of the pan/tilt acquires the newly set horizontal rotation speed and vertical rotation speed of the pan/tilt camera in the instruction content. The event processing is also to generate a new gimbal geographic time tag, but the gimbal geographic time tag is filled with empty values except for the horizontal rotation speed and vertical rotation speed of the gimbal, and the event type is a speed change event. When the next event occurs, when the PTZ geographic time tag is to be generated, if it is found that the event type of the previous PTZ geographic time tag is a speed change event, no new tag will be generated, but the new information cloud will be used to fill in those blanks field, and modify the event type to the type of the new event. This processing method is adopted mainly because the change of the speed of the pan-tilt will not directly affect the monitoring area of the current pan-tilt camera, but will affect the calculation of the monitoring area in the future. In this way, it can be ensured that when calculating the camera monitoring area at a certain moment in history, the accurate speed parameter when the event occurs can be obtained.

4) Recording the geographical time tags in order, and mapping them to the video clips according to the corresponding relationship in time;

1) Obtain the start time of the video clip, the end time, and the PTZ camera for shooting the video;

2) Find all geographical time tags of the PTZ camera, find out the geographical time tags whose time period overlaps with the time period of the video clip;

3) Corresponding the found geographic time tag set to the video segment. Use these geo-time tags as the set of geo-time tags for this video segment.

4) All the video clips participating in the retrieval are processed by the above-mentioned steps.

5) When carrying out video retrieval, take out the relevant information that can represent the video monitoring area in the geographic time tag, calculate the monitoring range of the PTZ camera on the GIS;

1) According to the relevant information of the PTZ in the geographical time tag, establish the quadrangular pyramid of the viewing area of the PTZ camera on the GIS, and the trapezoidal intersection of the quadrangular pyramid of the viewing area and the geographic plane of the map is the two-dimensional visible area of the PTZ on the map The lower base of the trapezoid is the intersection line between the farthest horizontal line that the PTZ can see and the geographical plane of the map, and the upper base of the trapezoid is the intersection line between the nearest horizontal line that the PTZ can see and the geographical plane of the map.

2) Calculate the geometric parameters of the trapezoidal intersection between the quadrangular pyramid of view and the geographical plane of the map according to the relevant information of the PTZ in the geographical time tag. The shape of the trapezoidal intersection is determined by the height of the PTZ and the vertical angle of the PTZ. The size of the surface is determined by the CCD magnification of the gimbal, and the position of the trapezoidal intersection is determined by the horizontal rotation angle of the gimbal. The specific calculation steps are as follows: set the horizontal viewing angle (βh) of the camera as ∠BAC in Figure 2, and the vertical viewing angle (βv) as ∠MAN in Figure 2. The horizontal rotation angle of the current position of the gimbal αh=∠VOP, the vertical angle of view αv=∠VAO, |OA|=H. The observed actual area is a trapezoidal area BCDE, and the observed area can be calculated by calculating the polar coordinates of the four points B, C, D, and E respectively.

Let ∠MAO be θ=αv-βv/2, then |OM|=H*tanθ, |AM|=H/cosθ. |BM|=|AM|*tan(βh/2)=(H/cosθ)*tan(βh/2), $\left|\mathrm{OB}\right|=\sqrt{{\left|\mathrm{om}\right|}^2+{\left|\mathrm{BM}\right|}^2}.$ Then ∠BOM=arctan(|BM|/|OM|) can be calculated. ∠BOP=αh-∠BOM. Find the polar coordinates of point B as (|OB|, ∠BOP). In the same way, the polar coordinates of C, D, and E can be obtained, so that the position and size of the trapezoidal intersection on the map can be determined.

6) Match the geographical area reflected by the geographical time tag with the retrieved target area, and find out the video recordings in the time period corresponding to the geographical time tag covering the searched area.

According to the area and time period of the query target, restore the geographical area scanned by the PTZ camera during this period. Match this area with the target area, and finally select all the recordings in the time period that match successfully.

The system requires the user to input the time period and monitoring area of the target video to be queried, which can be a circular range represented on the GIS. Then take out all the videos in the target time period, obtain their PTZ geographic time tag set, divide the video into different time segments according to these PTZ geographic time tags, and each segment represents the geographical area corresponding to its content. After calculating the scope of the quadrilateral area represented by the PTZ geographic time tag that can be represented on the GIS, then judge whether the circle of the target retrieval range overlaps with the quadrilateral of the actual monitoring area to determine whether it matches. If the matching is successful, the video recording within the time period corresponding to the PTZ change record is the retrieval result that meets the retrieval requirements. Take it out, and present.

Claims (4)

1. the monitor video searching method based on Geographic Information System is characterized in that comprising the steps:

1) obtains geographic position, setting height(from bottom), the angularity correction value information on Geographic Information System of monopod video camera;

2) when the The Cloud Terrace instruction of monopod video camera issues, the content that sends a The Cloud Terrace instruction simultaneously is to monitoring module, monitor module after detecting the The Cloud Terrace instruction issuing, judge the influence of The Cloud Terrace instruction to the guarded region scope of the captured video of monopod video camera, and acquisition is to the relevant information of the influential instruction execution of The Cloud Terrace guarded region scope back The Cloud Terrace, relevant information is meant the level angle and vertical corner information of video camera, CCD enlargement factor during shooting, and the The Cloud Terrace incident that causes above parameter to change, the action of assigning and carry out of a The Cloud Terrace instruction is called the The Cloud Terrace incident;

3) generate the geographical time tag of monopod video camera according to the relevant information obtained;

4) be mapped on the video segment with geographical time tag record in order, and according to temporal corresponding relation;

5) when recording a video retrieval, take out the relevant information that can represent video monitoring regional in the geographical time tag, calculate the monitoring range of monopod video camera on Geographic Information System;

6) the geographic area that geographical time tag reflected and the target area of retrieval are mated, find out covering by the video record of geographical time tag in the pairing time period of seek area;

Described with geographical time tag record in order, and be mapped to step on the video segment according to temporal corresponding relation:

1) obtains the zero-time of video segment, concluding time, the monopod video camera of capture video;

2) search all geographical time tags of monopod video camera, find out the free overlapping geographical time tag of time period of time period and video segment;

Geographical time tag collection and this video segment that 3) will find are mapped.

2. a kind of monitor video searching method based on Geographic Information System according to claim 1 is characterized in that relevant information that described basis obtains generates the geographical time tag step of monopod video camera:

1) fills in concluding time of a last geographical time tag of monopod video camera, calculate and rewrite the relevant information of a geographical time tag, make angle information, the CCD enlargement factor information when taking when taking accurately reflect angle information, the CCD enlargement factor of the monopod video camera of this geographical time tag finish time;

2) generate a new geographical time tag, fill in zero-time;

3) according to the The Cloud Terrace incident that causes generating geographical time tag, the content of different The Cloud Terrace incidents being filled in different geographical time tags.

3. a kind of monitor video searching method according to claim 1 based on Geographic Information System, it is characterized in that described when recording a video retrieval, take out the relevant information that can represent video monitoring regional in the geographical time tag, calculate the monitoring range step of monopod video camera on Geographic Information System:

1) according to the The Cloud Terrace relevant information in the geographical time tag, set up the ken rectangular pyramid of monopod video camera on GIS, the trapezoidal cross surface on the geographical plane of ken rectangular pyramid and map is the projection of the visual 2 dimensional region of The Cloud Terrace on map;

2) according to the The Cloud Terrace relevant information in the geographical time tag, calculate the geometric parameter of the trapezoidal cross surface on the geographical plane of ken rectangular pyramid and map, the shape of trapezoidal cross surface is determined at vertical corner with The Cloud Terrace by the height of The Cloud Terrace, the size of trapezoidal cross surface is determined that by the CCD enlargement factor of The Cloud Terrace the position of trapezoidal cross surface is determined by the level angle of The Cloud Terrace.

4. a kind of monitor video searching method according to claim 1 based on Geographic Information System, it is characterized in that described the geographic area that geographical time tag reflected and the target area of retrieval being mated, find out covering by the video record step of geographical time tag in the pairing time period of seek area:

1) mate with the figure of the target area of retrieving on Geographic Information System successively in the zone that geographical time tag calculated of concentrating according to the pairing geographical time tag of video segment;

2) find out the affiliated geographical time tag that two figures have overlapping areas;

3) video segment in the beginning and ending time of these geographical time tags is taken out, and, present as Query Result according to the time order and function sequential combination.

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