Video surveillance system using visual trail mapping

Abstract

System and method comprising: receiving a video stream and associated metadata stream from a mobile video camera travelling through a surveillance area; determining a trail of the movable camera based

Description

TECHNICAL FIELD The present disclosure generally relates to video surveillance systems, video 5 management systems and optionally computer-implemented video management methods that utilize trail mapping of one of movable video cameras onto a geomap of a surveillance area. BACKGROUND 10 Modern video surveillance systems have evolved into highly complex and often heterogeneous systems comprising a large number of different peripheral devices and computer hardware elements that are tied together via a networked infrastructure and controlled by means of advanced management software. One important component of modern video surveillance systems is a video recording 15 and processing system that allows video streams from one or more video cameras to be received, stored, and processed. A video management system (VMS), also known as video management software or a video management server, is a component or sub-system of a video 20 surveillance system. The VMS typically provides various video management services, such as one or more of the following: collecting one or more video streams from one or more video cameras, storing the received one or more video streams to a storage device and providing an interface to view the received one or more live video streams and / or to access one or more stored video streams. 25 Moreover, it is generally desirable that surveillance systems and in particular, VMSs are versatile and can be used in different types of applications which may impose different demands or requirements to processing and displaying received video streams supplied by the one or more video cameras. 30 A particular challenge to VMSs is to handle and display video streams supplied by moving or movable, i.e. non-stationary, video cameras in a meaningful and intuitive manner to a user e.g. a VMS operator. The present disclosure relates to 27 03 25 innovative layouts of user interface windows of the VMS using a plurality of trail markers mapped onto a geo-map of a surveillance area. The trail markers may indicate discrete time instants and corresponding geo-positions of the movable video camera along the trail. The user may actuate individual trail markers to get 5 a presentation of corresponding video streams. Hence, the functionality of present user interface windows inter alia addresses and solves the aboveoutlined challenges by providing meaningful and intuitive user presentations of live or retrieved video streams supplied by movable video cameras. 10 SUMMARY A first aspect of the invention relates to a VMS according to claim 1.. Optional features may be provided by claims 2 to 9. The VMS may provide the user with intuitive and fast access to locate and 15 investigate incidents and / objects of interest, i.e. target incidents and objects, in live video streams or recorded and retrieved video streams as discussed in further detail below with reference to the appended drawings. The processing unit may be configured to handle one or more additional movable 20 video cameras in certain embodiments of the video management system. In that case, the processing unit may further be configured to: - receive a second video stream from a second movable video camera configured for travelling through the surveillance area, - determine a second trail of the second movable video camera within the 25 surveillance area based on geographical position data and corresponding time data of the second metadata stream, - map the second trail onto the geo-map using a plurality of second trail markers represented by a second type of visual symbols, - monitor the plurality of second trail markers for user actuation e.g. a mouse 30 click), - respond to an actuated second trail marker by displaying the second video stream that corresponds to a geographical position and time instant of the actuated second trail marker. 27 03 25 The first and second types of visual symbols are preferably selected to make a clear and intuitive visual difference to the user. For example, each of first type of visual symbols comprise at least one of a rectangle, a triangle and a circle and each of second type of visual symbols comprise at least one of a rectangle, a 5 triangle and a circle. The visual symbols of the first and second types may for example differ by colour e.g. red versus black and / or by shape like rectangle versus triangle as discussed in further detail below with reference to the appended drawings. 10 The processing unit may be configured to create numerous different layouts of the user interface window for example depending on the number of video streams for presentation and other visual features associated with a particular 15 VMS. The processing unit may for example be configured to present the first video stream in a first tile of the user interface window and present the second video stream in a second tile of the user interface window. The processing unit may further be configured to present the geo-map in a third tile of the user interface window. This allows the user to access and evaluate visual features on 20 a single window. The processing unit may in some embodiments be configured to receive a user defined search query, or an automatically generated search query, for identifying at least one of a target object, a target activity and a target incident of the first 25 video stream within the surveillance area. The processing unit may thereafter display the first video stream that corresponds to the at least one of a target object, a target activity and a target incident in the user interface window. The user defined search query may for example identify a particular object or incident, say a target object within a user specified zone or facility of the surveillance area 30 and a user specified time period or span. 27 03 25 A second aspect of the invention relates to a video surveillance system that comprises a video management system according to described embodiments. Some embodiments of the video surveillance system may comprise one or more 5 stationary video cameras arranged at respective geo-positions of the surveillance area to generate respective one or more video streams and associated metadata streams; and a video management system according to any of above-outlined embodiments thereof and configured to receive the one or more video streams and associated metadata streams. 10 A third aspect of the invention relates to a computer-implemented video management method according to claim 12. Optional features may be provided by claims 13 to 14. 15 One embodiment of the computer-implemented video management method may comprise further steps of: - enter a user defined search query, or an automatically generated search query, for identifying at least one of a target object, a target activity and a target incident of the first video stream at a geo-position and time instant within the surveillance 20 area, - display the first video stream that corresponds to the identified at least one of a target object, a target activity and a target incident in the user interface window. One embodiment of the computer-implemented video management method may 25 comprise further steps of: - store the first video stream and associated first metadata streams in a video data repository and in a metadata repository, respectively, subsequent to receipt of the first video stream and associated first metadata stream, - retrieve and search the first video stream and associated first metadata stream 30 to identify the at least one of a target object, a target activity and a target incident by entering a user defined search query, or an automatically generated, search query, - map the first trail onto the geo-map corresponding to the retrieved first video stream and associated first metadata stream wherein the geo-map comprises 27 03 25 one or more first trail markers representing future time instants or time periods relative to the time instant of the identified at least one of a target object, a target activity and a target incident 5 The processing unit of the video management system may comprise a plurality of stored microprocessor executable program instructions configured to at least carry out one or more of the above-outlined steps of the computer-implemented video management method. BRIEF DESCRIPTION OF THE DRAWINGS 10 The above and other aspects will be apparent and elucidated from the embodiments described in the following with reference to the drawings in which: FIG. 1 is a schematic block diagram of an exemplary video surveillance system in accordance with some embodiments of the invention, 15 FIG. 2 illustrates on the upper and lower sections an exemplary schematic user interface window of a first embodiment of a video management system as displayed on a III client, 20 FIG. 3 illustrates on the upper and lower sections an exemplary schematic user interface window of a second embodiment of the video management system as displayed on a UI client, FIG. 4 illustrates on the upper and lower sections an exemplary schematic user 25 interface window as displayed on the UI client of a third embodiment of the video management system; and FIG. 5 shows a flow chart of an exemplary computer-implemented video management method that is suitable for the exemplary video management 30 systems disclosed herein. DETAILED DESCRIPTION FIG. 1 is a schematic block diagram of an exemplary video surveillance system 10. The video surveillance system 10 comprises one or more movable video 27 03 25 cameras 110 communicatively connected to a video management system (VMS) 100 via respective wired or wireless communication links or connections 150. Some embodiments of the video surveillance system 10 may comprise a mix of movable video cameras and stationary video cameras for example at least one 5 movable video camera 110 and a plurality of optional stationary video cameras 109, 111. The plurality of optional stationary video cameras 109, 111 are typically distributed across a predetermined area or space where surveillance is desired, i.e. surveillance area. The number and position / location of the optional stationary video cameras 109, 111 as well as the type of video camera comprised therein 10 may be selected based on factors such as a level of surveillance desired, a size of the surveillance area or facility and / or the complexity of the layout of the surveillance area or facility. Each of the optional stationary video cameras 109, 111 may provide surveillance in respective particular geographical zones, or subsections, of the surveillance area. The movable video camera(s) 110 has a Field 15 of view (FOV) 110a and the stationary video cameras 209, 111 have respective FOVs (not shown). The FOV is the open, observable area of the camera in question as schematically illustrated by a pie-shaped outline 110a of the movable video camera 110. The skilled person will appreciate that different types of video cameras may have different FOVs for example caused by different optical 20 properties of camera lenses. In the present specification, the term “movable” as a property of a video camera means the camera can be moved, i.e. is geographically dynamic, while carrying out video recording and / or live video streaming. The video recording and / or live 25 video streaming is often carried out during active operation of the video surveillance system 10 and its VMS 100. The movable video camera 110 is for example displaced along a certain path or trail of the surveillance area. A stationary video camera like optional cameras 109, 111 is typically fixed to a stationary structure, like a building wall or a pole in the surveillance area. 30 The movable video camera 110 may travel along a path or trail of the surveillance area via mounting to any suitable support structure of various types of vehicles for example motorized vehicles like cars, trucks, busses, trains, motorcycles, drones etc. The movable video camera 110 may be moved along the path or trail 27 03 25 of the surveillance area by being mounted on, or worn by, a person via a suitable support like a belt etc. The person may for example be a police officer, bus driver, fireman etc. In the latter situation the movable video camera 110 is transported through the surveillance area when the person walks or runs. Alternatively, the movable video camera 110 may be transported via the vehicle’s travel when the person wearing the movable video camera 110 is a driver or passenger of the vehicle. The one or more movable video camera(s) 110 may be conventional portable video camera(s) known as such in the art of video surveillance. It will be appreciated that the video surveillance system 10 may include a plurality of movable video cameras of the same type and / or different types. Different types of movable video cameras of the video surveillance system 10 may for example be tailored to specific operation schemes and placements, e.g. fixed to a truck or on-person fixations. The movable video cameras of different types may be configured to supply video streams of different resolution, in different formats or outputting additional metadata associated with the video stream. Examples of functions of the movable video cameras may include one or more of the following: video streaming, in particular live streaming, and / or video recording and audio streaming and / or audio recording. The video streaming and / or video recording may be carried out in visible wavelength ranges and / or in infrared wavelength ranges, such as near-infrared wavelength ranges. The moveable video camera(s) and optional stationary video cameras may comprise various control functions such as pan or zoom, image processing capabilities, motion detection, etc. The respective video streams supplied by the stationary video cameras 109, 111 as well as those of the one or more movable video cameras 200 are associated with corresponding metadata streams. The metadata stream may be a separate stream from the associated video stream but originating from either the same video camera or another device mounted on the same person or vehicle as the associated video camera. The metadata stream associated with each video stream preferably includes time data or stamps together with corresponding position data associated with the video camera in question. This property allows 27 03 25 time synchronization of the video streams and metadata streams at the VMS 100. The respective geolocations of the stationary video cameras 109, 111 and those of the one or more movable video cameras 110 may be derived from the position data supplied by a video camera associated with a GPS unit or similar position 5 detecting device. The associated GPS unit or device of a movable or stationary video camera may be built into the video camera as schematically illustrated by GPS device 101 of the movable video camera 110, or may fixed to a vehicle or person carrying the movable video camera in question. 10 The optional stationary video cameras 109, 111 as well as the one or more movable video cameras 110 are often communicatively connected to the video management system (VMS) 100 as mentioned above for example connected via a local area network 150 or in any other suitable manner, e.g. via point-to-point wired and / or wireless connections, or the like. For example, the optional 15 stationary video cameras 109, 111 may be connected to the VMS via an Ethernet connection. The one or more movable video cameras 110 may often be wirelessly connected to the VMS 100 for example through a wireless network like Wi-Fi, a 4G and / or 5G network. However, one or more of the movable video cameras 110 may alternatively be configured to record the video stream during 20 active operation where the video camera is transported through the surveillance area. In the latter scenario, the recorded video stream may be transferred to, or off-loaded at, a media repository 155 of the VMS 100 at the time of return to an associated station. In the latter use case, the video stream may be offloaded at regular time intervals for example when a camera user or cameral vehicle such 25 as a bus driver or police officer returns to the station. The skilled person will understand that some exemplary video surveillance systems may include additional sensors providing sensor signals and / or media streams different from video streams, such as audio signals, radar signals, Lidar 30 signals, etc. The VMS 100 is preferably configured to store the received video streams in the media repository 155. The VMS 100 provides an interface 170 for accessing live video streams as well as the previously discussed associated metadata streams. 27 03 25 The interface 170 may further be configured to access video streams and associated metadata streams stored in the media repository 155. The interface 170 may implement different types of interfaces. For example, the interface may provide an application interface, e.g. in the form of a software development kit 5 and / or one or more communication protocols, such as a suitable messaging protocol, e.g. SOAP, XML, etc. Accordingly, the interface may operate as a gateway to different types of systems. The VMS may be configured to implement various types of processing of received live video streams and / or recorded and retrieved video streams for example object detection, object recognition, motion 10 detection etc. The media repository 155 may comprise a media database or other suitable storage device for storing media content. The VMS 100 may include a user interface client (UI client) 400, for example configured to provide a user interface 15 window 215, 315, 415 (shown on Figs. 2, 3 and 4), displayed on a suitable user screen or screens of the VMS 100. The user interface window enables VMS users to see live video streams and / or stored and retrieved video streams and / or to control operation of one or more of the optional stationary video cameras 109, 111 and / or control operation of the one or more movable video cameras 110. The 20 content and structure of data items displayed through the user interface may be configurable by the operator via control buttons etc. The user interface preferably comprises a map component integrated in the VMS 100. The map component is utilized to build or provide a geo-map of at least a part of the surveillance area, for example a geographical zone, subsection of the surveillance area, for 25 presentation on the user screen via the user interface window. The map component may be configured to present a geo-map overview of the respective geo-positions of the one or more moveable video cameras 110 and optionally also the respective geo-positions of the optional stationary video cameras 109, 111. 30 The VMS 100 may be embodied as one or more software program(s) comprising respective computer executable instructions configured for execution on a suitable data processing system, e.g. by one or more server computers. The data processing system implementing the VMS is typically arranged remote from the 27 03 25 one or more movable video cameras 110 as the latter often travel over a large geographical area for example through a route or trail comprising various streets, roads, parking lots and other facilities. The route or trail may cover a city neighbourhood or even an entire city. The video streams from the movable video 5 camera(s) may be transmitted to the VMS 100 over wireless public or other wireless communications networks. Alternatively, the movable video camera(s) 110 of the video surveillance system 10 may move in relative proximity to a locally arranged on-site VMS 100 for example in a manufacturing facility, residential or office buildings, shopping centre etc. 10 The VMS 100 may comprise one or more camera drivers 180 for providing interfaces to respective types of stationary and movable video cameras. Different types of these video cameras may provide their respective video streams in different formats, e.g. using different encoding schemes and / or different network 15 protocols. Similarly, different cameras may provide different interfaces for camera control such as zoom or pan. Accordingly, the VMS 100 may include a plurality of different camera drivers 180 configured to cooperate with respective camera types. In particular, the camera drivers 180 may implement one or more suitable network protocols and / or other communications standards for transmitting data 20 between movable and stationary video cameras and / or other peripheral devices and data processing systems. Examples of such protocols and standards include the Open Network Video Interface Forum (ONVIF) standard and the Real Time Streaming Protocol (RTSP). 25 The camera drivers 180 may further be configured to add one time stamp to each frame of the received video streams 101 so as to ensure that the video streams, which are stored and subsequently supplied by the VMS 100, include a uniform time stamp. The added time stamp will also be referred to as a canonical time stamp. The canonical time stamp is indicative of the time of receipt, by the VMS 30 100, of the respective video streams from the respective stationary and movable video cameras. The camera drivers thus provide uniformly time-stamped input video streams each time-stamped input video stream 185 corresponding to a respective one of the received video streams. 27 03 25 The VMS 100 comprises a recording server 175. The recording server may be embodied as a software program module executed by a suitable data processing system, e.g. by one or more server computers. The recording server receives the inputted video streams 185 originating from the respective stationary and movable video cameras through the corresponding camera drivers 180. The recording server stores the received inputted video streams in a suitable media storage device, such as a suitable media database. It will be appreciated that the media repository 155 may be part of the VMS 100 or it may be separate from, but communicatively coupled to the VMS. The media repository 155 may be implemented as any suitable mass storage device, such as one or more hard disks or the like. The storing of the received video streams is also referred to as recording the received video streams. The recording server may receive and store additional data associated with received video streams such as the previously discussed metadata stream. The VMS 100 may store the generated metadata in a suitable metadata repository 165, such as a suitable metadata database, which may be separate from, or integrated into, the media repository 155. To this end, the VMS 100 may include an index server 160. The index server 160 may be embodied as a software program module executed by a suitable data processing system, e.g. by one or more server computers. The index server may receive metadata and store the received metadata in the metadata repository 165. The index server may further index the stored metadata so as to allow faster subsequent search and retrieval of stored metadata. During searches through the stored video and metadata streams the metadata repository 165 may be accessed through the interface 170 and index server 160. The III client 400 may query the index server 160 through the interface 170 and return matching search results. The UI client 400 may be configured to respond to receipt of the matching search results by determining the corresponding position data of the metadata stream in question. The UI client 400 may be configured to utilize the time stamps of the metadata stream in question to find the positions on the geo-map that correspond to the matching search results. 27 03 25 The lowermost section of FIG. 2 illustrates an exemplary and schematic geo-map 250 of a surveillance area taken at a particular time instant of interest. The uppermost section of FIG. 2 shows an exemplary user interface window 215 of the VMS 100 associated with the geo-map in schematic form. The exemplary user interface window 215 may be displayed via a suitable screen or display of the III client 400 on FIG. 1. The user interface window 215 may be presented to an operator or user of the VMS 100. The moveable video camera 200 may be mounted to a suitable support structure of an exemplary vehicle 202 for example motorized vehicles like cars, trucks, busses, trains, motorcycles etc. to be moved or transported along a path or trail 272 of the geo-map area 250. The movable video camera 200 may alternatively be moved or transported along the trail 272 of the area by way of mounting on, or worn by, a person via a suitable support like a belt etc. The movable video camera 200 has a travel direction, or heading, along the road section 600 as schematically indicated by the heading arrow. The processing unit is configured to generate the geo-map 250 of the surveillance area and display the geo-map 250 on the user interface window 215. The trail 272 of the movable video camera 200, as determined by the processing unit, is represented by a plurality of first trail markers 270 that are represented by a first type of visual symbols, e.g. open triangles. The skilled person will understand that multiple alternative types of symbols may be used by the processing unit as the first trail markers for example rectangles, stars, circles etc. The type of symbol should preferably possess an intuitive visual differentiation to other features of the geo-map and may for example use a particular coloring of the visual symbols. The processing unit is configured to determine the trail 272 of the movable video camera 200 by utilizing position data and corresponding time data of the associated first metadata stream. Each of the first trail markers 270, 270a of the trail 272 on the geo-map 250 may correspond to a particular geo-position and time instant reported by the associated position detecting unit 201 of the vehicle 202. The skilled person will appreciate that one or more of the geo-positions of 27 03 25 the first trail markers 270, 270a may be determined by the processing unit by use of interpolation and / or extrapolation algorithms between a plurality of discrete position data and time data reported by the associated position detecting unit 201 of the vehicle 202. The processing unit is configured to monitor the first trail markers 270, 270a for a user actuation thereof for example by a screen pointing device like a mouse click or pressing on a touch-sensitive screen. The processing unit is further configured to present a first video stream that corresponds to the geographical position and time instant of the actuated trail marker 270a. This actuation of the first trail marker 270a is schematically indicated by an arrow 225 as actuation device. The processing unit is preferably configured to display a corresponding time instant or period of the first video stream in response to the actuation of the first trail marker 270a in a first tile 275 the UIW215. The position and time instance, or time period, of the first movable video camera 200 associated with the first video stream may be derived from a search result or hit of a particular search query entered into the processing unit of the VMS 100 by the operator for example via a search window or box 222 of the IIIW 215. The search query may be applied to live video streams, i.e. real-time streaming, or may be applied to previously stored and later retrieved video streams as discussed in further detail below with reference to FIG. 4. The search query aims at identifying a particular object or incident, say a target object like a red sedan car, a road accident, a person with certain characteristics etc. within a specified zone and time period or span. In the present example, the target object is depicted by a person 205 for simplicity. The person 205 is arranged in a field-of-view (FOV) 200a of the movable video camera 200 at the specified time instant and particular geo-position on the trail 272 to generate a search hit or result in the corresponding video stream. The user is able to monitor the first trail markers 270, 270a on the geo-map 250 using the UIW 215 and quickly identify past geo-positions of the vehicle 202 and associated video camera 200. The marking of the continuous trail 272 on the 27 03 25 geo-map is optional but may serve to further augment visual indications already made by the first trail markers 270, 270a. This visual presentation of the first trail markers 270, 270 on the geo-map 250 via the UIW 215 allows the user to jump back to prior time instant or periods and corresponding geo-positions of the 5 movable video camera 200 relative to the time instant and geo-positions of search results like the target person 205. The user is accordingly provided with an intuitive and fast access to locate and investigate incidents and / objects of interest before the search hit in question for example the illustrated target person 205. 10 FIG. 3 illustrates second embodiment of a video management system configured to handle respective video streams and metadata streams of at least two moveable video cameras, i.e. a first camera 300 and a second camera 310 according to a second embodiment of the present invention. An exemplary geo-15 map 350 of a surveillance area of the corresponding video surveillance system taken at a particular time instant of interest is depicted schematically on the lowermost section. The skilled person will appreciate that corresponding features, structures and 20 functions to those of the first embodiment on FIG. 2 are given corresponding reference numerals and will not necessarily be described in connection with the present embodiment for brevity. The uppermost section of FIG. 3 shows an exemplary user interface window 25 (UIW) 315 of the VMS 100 in schematic form. The exemplary user interface window 315 may be displayed via a suitable screen or display of the UI client 400 on FIG. 1. The video surveillance system further comprises a plurality of optional stationary video cameras marked schematically by “x”. The plurality of optional stationary video cameras are typically distributed across a predetermined area or 30 space where surveillance is desired. The video management system may be configured to receive respective video streams and metadata streams associated with the optional stationary video cameras and for example display one or more video streams in the UIW 315. The video management system may identify and select one or more stationary video cameras positioned nearby the movable 27 03 25 video camera in question at the relevant time instant and geo-position thereof to obtain additional video stream footage of an incident or object of interest. The processing unit is configured to generate the geo-map 350 of the surveillance area and display the geo-map 350 on or via the UIW 315. The first trail markers 370, 370a of the first trail 372 on the geo-map 350 may correspond to respective geo-positions and time instants reported by the associated position detecting unit 301 of the first vehicle 302 via the first metadata stream. The processing unit is configured to map the plurality of first trail markers 370, 370a at their respective geo-positions on the geo-map 350. The first trail markers 370, 370a are represented by a first type of visual symbols, e.g. open triangles as indicated. The processing unit is further configured to receive a second video stream supplied by the second movable video camera 310 attached to the second movable vehicle 312. The second movable video camera 310 is configured for travelling through the surveillance area in a similar manner to the first movable video camera 300, albeit typically along an independent trail 362 as indicated by a plurality of second trail markers 360, 360a. The second trail markers 360, 360a on the geo-map 350 may correspond to respective geo-positions and time instants reported by the associated position detecting unit 311 of the second vehicle 312 via the second metadata stream. The second markers 360, 360a are represented by a second type of visual symbols, e.g. filled-out dots / circles as indicated to create a clear and distinct visual difference between the first and second trails. The processing unit is configured to monitor the first trail markers 370, 370a for a user actuation thereof for example by a screen pointing device like a mouse click or pressing on a touch-sensitive screen. The processing unit is further configured to present a first video stream that corresponds to the geographical position and time instant of the actuated trail marker 370a of the first trail 372. This actuation of the first trail marker 370a is schematically indicated by an arrow 325a as actuation device. The processing unit is preferably configured to display the 27 03 25 corresponding time instant or period of the first video stream in response to the actuation of the first trail marker 370a in a first tile 375 of the UIW 315. The processing unit is in a similar manner configured to monitor the second trail markers 360, 360a for a user actuation thereof. The processing unit is further 5 configured to present a second video stream that corresponds to the geographical position and time instant or period of the actuated trail marker 360a of the second trail 362. This actuation of the second trail marker 360a is schematically indicated by an arrow 325b as actuation device. The processing unit is preferably configured to display the corresponding time instant or period of 10 the second video stream in response to the actuation of the second trail marker 360a in a second tile 365 of the UIW 315. The skilled person will understand that the layout of UIW 315 is an exemplary embodiment where the first and second tiles 375, 365 are rectangular with largely similar dimensions. Numerous alternative shapes, dimensions and locations of the first and second tiles 375, 15 365 within the UIW 315 may be utilized for example depending on the number of movable cameras, other features and tiles of the UIW etc. FIG. 4 illustrates third embodiment of a video management system configured to handle respective video streams and metadata streams of one or more moveable 20 video cameras, i.e. at least a first camera 400 according to a third embodiment of the present invention. An exemplary geo-map 450 of a surveillance area of the corresponding video surveillance system taken at a particular time instant of interest is depicted schematically on the lowermost section. 25 The skilled person will appreciate that corresponding features, structures and functions to those of the first embodiment on FIG. 2 are given corresponding reference numerals and will not necessarily be described in connection with the present embodiment for brevity. 30 The processing unit is configured to generate the geo-map 450 of the surveillance area and display the geo-map 450 on to the user via UIW 415. A trail 472 of the movable video camera 400 as determined by the processing unit is represented by a plurality of first trail markers 470, 470a, 470b represented by e.g. open triangles as indicated. The processing unit is configured to determine 27 03 25 the trail 472 of the movable video camera 400 by utilizing position data and corresponding time data of an associated first metadata stream. Each of the first trail markers 470, 470a, 470b of the trail 472 on the geo-map 450 may correspond to a particular position and time instant reported by the associated position detecting unit 401 of the vehicle 402 following similar functions to those discussed above. The position and time instant, or time period, of the first movable video camera 400 associated with the first video stream may be derived from a search result or hit of a particular search query entered into the processing unit of the VMS 100 by the operator for example via a search window or box 422 of the IIIW 415. The present exemplary search query leads to the identification of the search object 405 e.g. a person at a particular time instant and geo-position on the trail 472. The present processing unit is configured to additionally retrieve and search through previously stored video frames or sections of the first video stream, i.e. non-live frames, from the earlier discussed video repository of the VMS. The processing unit is configured to map the first trail onto the geo-map 450 corresponding to the retrieved frames and sections of the first video stream. This feature allows the processing unit to not only map those first trail markers 470, 470a that represent geo-positions and time instants of the past, i.e. to the left of vehicle 420, but additionally map those first trail markers 470b that represent future geo-positions and time instants of the search object 405 relative to the geo-position and time instant. Using a similar scheme as discussed in the previous embodiments, the processing unit is configured to monitor each of the first trail markers 470, 470a, 470b for a user actuation thereof for example by a screen pointing device. The processing unit is further configured to display or present the first video stream on the first tile 475 of the UIW 415 where the first video stream corresponds to the geographical position and time instant of the movable camera 400 at the actuated first trail marker 470a. The latter video stream represents a past time instant or period. The processing unit further responds to actuation of the trail marker 470b that represents future geo-positions and corresponding time instants 27 03 25 of the movable video camera 400 by displaying the corresponding time instant or period of the first video stream on the first tile 475 of the UI W 415. FIG. 5 shows a flow chart or diagram of an exemplary computer-implemented 5 video management method, suitable for the previously disclosed surveillance systems and video management systems (VMS). In step 805 a processing unit of the VMS receives a plurality of video streams and associated metadata streams supplied by one or more movable video 10 cameras, and optionally one or more stationary video cameras. In step 810 the processing unit builds or creates a geo-map of the surveillance area for example based on information from a suitable cloud-based geodatabase. 15 In step 815 the processing unit determines and maps a first trail of a first movable video camera based on geographical position data and corresponding time data of a corresponding first metadata stream. 20 In step 820 the processing unit visually indicates the first trail by a plurality of first trail markers represented by a first type of visual symbols for example symbol shapes like stars, rectangles, triangles, dots etc. In step 825 the processing unit monitors the plurality of first trail markers for user 25 actuation for example by a mouse click, touch screen pressure etc. In step 830 the processing unit detects an actuated first trail marker. In step 835 the processing unit responds to the actuation by displaying the first 30 video stream in a tile of the UIW wherein the first video stream corresponds to a geographical position and time instant of the actuated first trail marker. In step 840 the processing unit checks whether there is additional movable video camera(s) in the surveillance area at the time instant and associated with the VMS. If yes, the processing unit jumps back to step 815 and carries out corresponding steps 815 - 835 for the further video camera(s). 27 03 25 27 03 25

Claims

1. A video management system for use in a video surveillance system, comprising:5 a processing unit configured to receive a first video stream and an associated first metadata stream, the first video stream being supplied by a first movable video camera in the video surveillance system configured fortravelling through a surveillance area of the video surveillance system,- a user interface window configured to present the first video stream; wherein10 said processing unit is further configured to:- receive a search query for identifying at least one of a target object, a target activity and a target incident of the first video stream within the surveillance area, - determine a first trail of the first movable video camera within the surveillance area based on geographical position data from the first metadata stream and15 corresponding time data of the first metadata stream,- generate and display a geo-map of the surveillance area via the user interface window,- map the first trail onto the geo-map by providing a plurality of spaced apart individual first trail markers represented by a first type of visual symbols, wherein20 each trail marker indicates a time instant and corresponding geo-position of the movable camera along the trail, wherein at least one of the first trail markers is associated with the result of the search query,- monitor the plurality of first trail markers for user selection of one of the trail markers,25 - respond to the selection of the first trail marker by displaying the first videostream that corresponds to a geographical position and time instant of the selected first trail marker.

2. A video management system according to claim 1, wherein the processing unit 30 is further configured to:- receive a second video stream and an associated second metadata stream, the second video stream being from a second movable video camera configured for travelling through the surveillance area,27 03 25- determine a second trail of the second movable video camera within the surveillance area based on geographical position data of the second metadata stream and corresponding time data of the second metadata stream,- map the second trail onto the geo-map using a plurality of spaced apart second trail markers represented by a second type of visual symbols,- monitor the plurality of second trail markers for user selection,- respond to the selection of the second trail marker by displaying the second video stream that corresponds to a geographical position and time instant of the selected second trail marker.

3. A video management system according to claim 2, wherein said processing unit is further configured to:- present the first video stream in a first tile of the user interface window - present the second video stream in a second tile of the user interface window, and optionally present the geo-map in a third tile of the user interface window.

4. A video management system according to any of the preceding claims, wherein each of first type of visual symbols comprise at least one of a rectangle, a triangle and a circle and each of second type of visual symbols comprise at least one of a rectangle, a triangle and a circle.

5. A video management system according to any of the preceding claims, wherein each of the first type of visual symbols and each of the second type of visual symbols differ at least by respective colors.

6. A video management system according to any of the preceding claims, wherein said processing unit is further configured to:- receive a user defined search query, or an automatically generated search query, for identifying the at least one of a target object, a target activity and a target incident of the first video stream within the surveillance area,- display the first video stream that corresponds to the at least one of a target object, a target activity and a target incident in the user interface window.27 03 257. A video management system according to any of the preceding claims, wherein the search query is a user defined search query or an automatically generated search query.5 8. A video management system according any of the preceding claims, wherein atleast one trail marker of the plurality of trail markers corresponds to a geographical position determined from the first metadata stream.

9. A video management system according to any of the preceding claims, wherein 10 at least some of the plurality of trail markers are interpolated based on a geographical position determined from the first metadata stream.

10. A video surveillance system comprising at least a first movable video camera and a video management system according to any of the preceding claims.1511. A video surveillance system according to claim 10, comprising one or more stationary video cameras arranged a respective geo-positions of the surveillance area to generate respective one or more video streams and associated metadata streams; and20 a video management system according to any of the preceding claims; wherein said video management system is configured to receive the one or more video streams and associated metadata streams supplied by respective ones of the one or more stationary video cameras.25 12. A computer-implemented video management method for a video surveillancesystem, comprising the steps of:a) receive, at a video management system, a first video stream and an associated first metadata stream, the first video stream being supplied by a first movable video camera in the video surveillance system30 configured for travelling through a surveillance area of the videosurveillance system;27 03 25b) determine a first trail of the first movable video camera within the surveillance area based on geographical position data of the first metadata stream and corresponding time data of the first metadata stream;c) search at least one of the first video stream and the first metadata stream to identify at least one or a target object, a target activity and a target incident at a geo-position and a time instant within the surveillance area, wherein the search is performed based on a search query;d) generate and display a geo-map of the surveillance area via the user interface window;e) map the first trail onto the geo-map by providing a plurality of spaced apart individual first trail markers represented by a first type of visual symbols, where each trail marker indicates a time instant and corresponding geo-position of the movable camera along the trail, wherein at least one of the first trail markers is associated with the result of the search query;f) monitor the plurality of first trail markers for user selection;g) respond to the selection of the first trail marker by displaying the first video stream that corresponds to a geographical position and time instant of the selected first trail marker.

13. A computer-implemented video management method according to claim 12, further comprising the step of:h) enter a user defined search query, or an automatically generated search query, for identifying at the least one of a target object, a target activity and a target incident of the first video stream at a geo-position and time instant within the surveillance area,i) display the first video stream that corresponds to the identified at least one of a target object, a target activity and a target incident in the user interface window.

14. A computer-implemented video management method according to claim 13, further comprising steps of:27 03 25- store the first video stream and the associated first metadata streams in a video data repository and in a metadata repository, respectively, subsequent to step a) of claim 13;- retrieve the first video stream and associated first metadata stream to identify5 the at least one of a target object, a target activity and a target incident according to step f) of claim 13,- map the first trail onto the geo-map corresponding to the retrieved first video stream and associated first metadata stream wherein the map comprises one or more first trail markers representing future time instants or time periods relative to10 the time instant of the identified at least one of a target object, a target activity and a target incident.

15. A video management system comprising a processing unit storing a plurality of microprocessor executable program instructions configured to at least carry15 out steps a) - g) of the computer-implemented video management method of claim 12.202530

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