WO2016195533A1

WO2016195533A1 - Device for reducing ptz camera positioning error

Info

Publication number: WO2016195533A1
Application number: PCT/RU2015/000810
Authority: WO
Inventors: Иван Сергеевич ШИШАЛОВ; Андрей Викторович ФИЛИМОНОВ
Original assignee: Общество С Ограниченной Ответственностью "Дисикон"
Priority date: 2015-05-29
Filing date: 2015-11-23
Publication date: 2016-12-08

Abstract

The present technical solution relates to the field of video monitoring, and specifically to video monitoring using rotary (PTZ) cameras. A device for reducing PTZ camera positioning error, including: a PTZ-camera, a data processing unit, a data storage unit and a program, the program being stored in the data storage unit and being executed in the data processing unit, wherein the program includes the following instructions: a command processing unit receiving a PTZ-camera target rotation position, then the command processing unit determining at least one intermediate camera position and the coordinates thereof based on the camera target rotation position data, then the command processing unit sending a command for the PTZ camera to rotate sequentially to the target position via the aforementioned intermediate positions. The technical result consists in reducing camera positioning error and increasing the repeatability of positioning.

Description

PTZ CAMERA POSITIONING ERROR DEVICE

FIELD OF TECHNOLOGY

This technical solution relates to the field of video surveillance, in particular to video surveillance using PTZ cameras.

BACKGROUND OF THE INVENTION

Currently, PTZ cameras are widely used to monitor large areas. They are a device that supports remote control of viewing direction and zoom. ΡΤΖ-cameras are actively used when conducting video conferences, being a necessary attribute of a conference room or meeting room, when building security systems and other video surveillance systems. Due to their high prevalence at the moment, the range of cameras is quite extensive, cameras have different characteristics and cost.

When using a PTZ camera for video surveillance, an important characteristic of its functioning is the camera positioning error, it depends on the degree of wear of the mechanism, its initial accuracy, and camera calibration.

The prior art article is known [1], which describes the approaches that are used in solving the problem.

Sinha and Polleface proposed a positioning device for ΡΤΖ-cameras [2], in which the camera is first calibrated at low zoom, and then the internal parameters of the camera are calculated with increasing zoom. Since calibration is performed discretely from one zoom value to another, piecewise linear interpolation is used to calculate the internal parameters. Using this method provides the need for a large number of calibration steps to mitigate noise, which significantly increases the operating time.

ESSENCE

This technical solution is aimed at eliminating the disadvantages inherent in solutions known from the prior art.

The technical result is to reduce errors and increase the repeatability of positioning.

This technical result is achieved through the use of intermediate positioning points, which reduce the effect of inertia and "flight" of the required position. By reducing the positioning error, the positioning accuracy is improved. Another technical result is the repeatability of positioning results. As a result, the positioning error becomes systematic and the same.

A device for reducing the positioning error of a PTZ camera includes: a PTZ camera, a data processing unit, a data storage unit, a program that is stored on the data storage unit and executed on the data processing unit, the program including the following instructions: the command processing unit receives the target rotation position ΡΤΖ cameras, then the command processing unit determines at least one intermediate position of the camera and its coordinates based on the data about the target position of camera rotation, after which the command processing unit sends commands ΡΤΖ-camera sequentially rotates to the target position through the aforementioned intermediate positions.

In some embodiments, the data processing unit includes an instruction receiving unit and a control unit configured to display information in the data output unit.

In some embodiments, at least one intermediate position and its coordinates are determined by testing the camera.

In some embodiments, at least one intermediate position and its coordinates are determined on the basis of ideas about the method of operation and the characteristics of the pivoting mechanism of the camera.

In some embodiments, the intermediate points may be determined through absolute coordinates or through relative coordinates.

In some embodiments, the number and coordinates of intermediate positions depend on the required speed and positioning accuracy.

In some embodiments, the relative coordinates of the intermediate position are determined so that the intermediate position is as close to the desired position.

In some embodiments, computer vision algorithms are used to determine positioning errors.

In some embodiments, at least two intermediate positions are determined, the first position being different by A in the panoramic angle and the angle of inclination from the desired position, and the second intermediate position in the panoramic angle is the same as the desired position, and in the angle of inclination different by A.

In some embodiments, at least two intermediate positions are determined, the first position being different by A in the panoramic angle and the angle of inclination from the desired position, and the second intermediate position in the angle of inclination coincides with the desired position, and in the panoramic angle different by A. In some embodiments, the speed of movement from the starting point to the first intermediate, between the intermediate and between the last intermediate point and the target point may be different.

BRIEF DESCRIPTION OF THE DRAWINGS

The signs and advantages of this technical solution will become apparent from the following detailed description and the accompanying drawings, in which:

Figure 1 - shows a block diagram of the functional interaction of the elements in the device; Figure 2 - shows a block diagram of an example implementation of the inventive device;

In Fig.Z - an example implementation of a technical solution with one intermediate point.

Figure 4 is an external view of the device;

DETAILED DISCLOSURE OF TECHNICAL SOLUTION

Below will be described the concepts and definitions necessary for the detailed disclosure of the ongoing technical solution.

A panoramic angle (precession angle, Pan) is one of the Euler angles that describes the rotation of an object around the Z axis (for more details, see [9]). This angle corresponds to the rotation of the object in its own horizontal plane.

The angle of inclination (nutation angle, Tilt) is one of the Euler angles that describes the rotation of an object around the Y axis (for more details, see [9]). This angle corresponds to the rotation of the object in its own vertical plane.

Positioning error - the difference between the target position of the camera and the actual position of the camera after positioning in the target position. It is expressed by two angles: panoramic (corresponding to the difference between the panoramic angles of the actual and target position) and the angle of inclination (corresponding to the difference between the angle of inclination of the actual and target position).

Repeatability of a result is a characteristic that reflects the probability of a repetition of the result of an experiment subject to a certain set of initial conditions.

The repeatability of the positioning result is a characteristic that reflects the probability of achieving the same values of the positioning error while maintaining the target position of the camera and changing the initial position. In the standard positioning mode, if necessary, rotate the camera, the command processing unit 200 (FIG. 2) sends the камере-camera 209 a rotation command from the initial position to the target position:

- the initial position of the camera, which is characterized by panoramic

the angle Rasc and the angle of inclination Tilt _x , Pos _D1 (Pan _D + Pan _Erl ; Tilt _D + Tilt _Erl ) - the camera position when the camera moves from point 1 to the target position, it differs from the desired target position Pos _D (Pan _D ; Tilt _D ) by the value of the positioning error.

In this case, turning to the same target position from a different starting position generally leads to other positioning errors:

Pos ₂ (Pan ₂ ; Tilt ₂ ) - the second initial position of the camera orientation, which differs from the first values of the panoramic angle and tilt angle; Pos _D2 (Pan _D + Pan _Er2 ; Tilt _D + Tilt _Er2 ) - the orientation of the camera when it _comes to the target position from starting position 2, with other error values for the panoramic angle and angle of inclination. The resulting position also differs from the desired target direction of the camera view.

With this approach, the scatter of Pan _Er values; Tilt _Er can reach significant values, and for cameras with different rotation mechanisms, the error will be from 0.05 degrees to 0.5 degrees. Various rotation mechanisms are described in [4]. This technical solution proposes the introduction of at least one additional position through which the camera passes before reaching the target position, which allows to reduce the positioning error:

Similar to the previous one: the first starting position.

Pos _Int1 (Pan _Int + Pan _Erl ) Tilt _lnt + Tilt _Erl ) - an intermediate position with its own positioning error when repositioning from the first starting position.

Pos _D1 (Pan _D + Pan _MErl ; Tilt _D + Tilt _MErX ) ~ end (target) position when repositioning from an intermediate position.

Pos ₂ (Pan ₂ ; Tilt ₂ ) - second starting position, different from the first starting position. Pos _Int2 (Pan _int + Pan _Er2 ; Tilt _Int + Tilt _Er2 ) - an intermediate position with its own positioning error when repositioning from the second initial position.

Pos _D2 (Pan _D + Pan _MEr2 ; Tilt _D + Tilt _MErZ ) - the end position upon arrival from an intermediate position. Because the точку-camera 209 is positioned at the final point from an intermediate point, the coordinates of which in the two described driving routes may differ by no more than a positioning error (from 0.05 to 0.5 degrees), the final error is Pan _MEr ; Tilt _MEr will be significantly smaller, and for cameras with a positioning accuracy of 0.05 degrees, it can already be about 0.01 degrees.

The necessary effect is achieved at the cost of some loss of time required for intermediate positioning and control of the installation of the rotary mechanism in the intermediate position. However, for many tasks, accuracy, which is achieved by reducing positioning error, is a priority. In addition, modern cameras have a very high positioning speed, which reduces the time spent on additional positioning to a minimum.

According to FIG. 2, a device for implementing a technical solution includes an instruction processing unit 200. An instruction processing unit 200 may be configured as a client, server, mobile device, or any other computing device that interacts with data in a collaboration system. In the most basic configuration, the data processing unit 200 typically includes at least one processor 201 and a data storage unit 202. Depending on the exact configuration and type of computing device, system memory 202 may be volatile (e.g., random access memory (RAM, RAM)), non-volatile (for example, read-only memory (ROM)), or some combination thereof. The data storage unit 202 typically includes one or more application programs 203 and may include program data 204. The functional principle of operation is shown in FIG. 1, in which the steps of the method are indicated as 101, 102,103. The present technical solution is implemented in application programs 203, the functional principle of operation being shown in FIG. 1, in which the steps of the method are indicated as 101, 102,103.

the command processing unit 200 (FIG. 2) receives the target rotation position of the PTZ camera;

The target position is understood as the camera position defined by the camera control program or the operator. Thus, the target rotation position of the камеры-camera is transmitted to the command processing unit 200 either from the input device 205 or from the data storage unit 202. The essence of the technical solution does not depend on the method of obtaining the target position.

the command processing unit 200 determines at least one intermediate position of the camera and its coordinates based on the target rotation position of the camera; The command processing unit 200 determines the intermediate positions and their coordinates by testing the device, or on the basis of ideas about the configuration of the camera rotary mechanism. During testing, global optimization algorithms can be used to obtain optimal parameters of intermediate points [6,7,8].

Intermediate positions can be defined through absolute coordinates or through relative coordinates.

The number of intermediate positions depends on the required speed and positioning accuracy. The higher the positioning speed is required, the less intermediate positioning points should be, and in some cases one intermediate positioning point may be sufficient. It is also obvious from general considerations that increasing the number of intermediate points beyond a certain limit will not increase the accuracy of positioning.

The speed and accuracy of positioning can be set either from the input device 205, or from the data storage unit 202, depending on the specific application of the camera.

In some embodiments, the definition of intermediate points build an automatic procedure for calculating the resulting positioning accuracy at a given speed and vice versa, the resulting positioning speed at the required accuracy.

In a particular case, testing to determine intermediate positions can occur as follows:

1. The command processing unit 200 randomly determines the target position of the camera.

2. The command processing unit 200 sends the камере-camera 209 a command to move to an arbitrary point, then immediately sends the command to return to the target position according to a certain positioning algorithm, measuring accuracy and positioning speed.

3. The command processing unit 200 changes the positioning algorithm and again measures the accuracy of the positioning.

When changing the positioning algorithm, it implies both the choice of another algorithm and the setting of the current one.

In this case, various strategies for changing the positioning algorithm can be used, including the simplest ones. Let us give an example of a simple strategy for determining a positioning algorithm: the command processing unit 200 selects one intermediate position that differs from the target by the panoramic angle and angle of inclination by A. Then, using the global optimization algorithm [6,7,8] for a one-dimensional function, choose this value A which corresponds to a minimum positioning error.

To determine the positioning error, computer vision algorithms can be used, for example, realizing the integration of control points on two frames and determining the offset of the anchor points between frames. The search for reference points can be performed as indicated in the information source [5]. In the particular case, two images can be used - the first obtained at the target point at the initial moment of time, and the second obtained at the target position after positioning from an intermediate position. Next, these images are compared and a positioning error is determined.

the command processing unit 200 sends the command to the ΡΤΖ-camera 209 sequential rotation to the target position through the aforementioned intermediate positions.

After receiving the target position and calculating a set of intermediate positions, the command processing unit 200 sends the command to the камере-camera 209 of successive rotation to the target position through the first intermediate position, then, if it is present, to the second, and so on. The final step is to rotate the camera to the target position. The command processing unit 401 (FIG. 4) is physically implemented in the ΡΤΖ-camera 402.

The command processing unit 200 (FIG. 2) may have additional features or functionality. For example, the command processing unit 200 may also include additional data storage devices (removable and non-removable), such as, for example, magnetic disks, optical disks, or tape. Such additional storages are illustrated in FIG. 2 through removable storage 207 and non-removable storage 208. Computer storage media may include volatile and non-volatile, removable and non-removable media implemented in any way or using any technology for storing information, such as machine-readable instructions, data structures, program modules, or other data. A storage unit 202, removable storage 207, and non-removable storage 208 are examples of computer storage media. Computer storage media includes, but is not limited to, random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact ROM a disc (CD-ROM), universal digital disks (DVDs) or other optical storage devices, magnetic tapes, magnetic tapes, magnetic disk storage or other magnetic storage devices, or any other medium that may be used on to store the desired information and which can be accessed by the command processing unit 200. Any such computer storage medium may be part of the unit 200. The command processing unit 200 may also include input unit (s) 205, such as a keyboard, mouse, pen , a voice input device, a touch input device, and so on. Block (s) 206 output, such as a display, speakers, and the like, can also be included in the device.

The command processing unit 200 comprises communication connections that allow the device to communicate with other computing devices. Communication connection is an example of a communication environment. Typically, a communications environment can be implemented using machine-readable instructions, data structures, software modules, or other data in a modulated information signal, such as a carrier wave, or in another transport mechanism, and includes any information delivery medium. The term "modulated information signal" means a signal, one or more of its characteristics are changed or set in such a way as to encode information in this signal. By way of example, but without limitation, communication media include wired media such as a wired network or a direct wired connection. The term “machine-readable medium”, as used herein, includes both storage media and communication media.

Elements of this device (Figure 4) are in constructive unity and functional relationship, and their joint use leads to the creation of a new device with a new function. To an expert in the art, it is obvious that the appearance of the camera with a pivoting mechanism is not limiting. Thus, the design can be performed in any design that does not affect the essence of the technical solution. EXAMPLES OF IMPLEMENTATION

Let there be a camera model that allows positioning at different speeds. It is also known that due to the inertia of the mechanism, an attempt to position the camera at a point (Pan, Tilt) leads to positioning at a point (Pan + Perr, Tilt + Terr), where (Perr, Terr) is a positioning error, the magnitude of which depends on the speed the camera’s movement to the positioning point, and the direction depends on the motion vector that the camera possessed when it reached the target position. Thus, positioning at maximum speed results in a maximum error. The direction of the error is also unpredictable, because it depends on the position in which the camera was before the start of positioning. Positioning at a low speed would reduce the error, but would significantly increase the positioning time if the initial position of the camera and the target position are significantly different. During testing the capabilities of the camera’s rotary mechanism, it turned out that in order to achieve the minimum positioning error, it is enough to determine one intermediate point that differs from the target position by one degree in the panoramic angle and angle of inclination and move from the intermediate position to the target one with a minimum speed. Moreover, an increase in the distance between the target position and the intermediate one does not lead to a decrease in the error, but, of course, leads to an increase in the positioning time. At the same time, a further reduction in distance leads to an increase in positioning error. Thus, a distance of one degree at two angles is optimal in terms of reducing positioning errors.

The following is an example of the implementation of a technical solution (Fig. C), in which there is one intermediate point (Pan - 1 °, Tilt - 1 °). The definition of the intermediate position (Pan -, Tilt -) is given in the absolute coordinates of the camera, but can also be determined in relative coordinates. Moreover, if the initial position of the camera was (Figx, Tisx), then the relative position of the intermediate point will be (Pan - 1 - Figx, Tilt - 1 - Tisx) and will correspond to the offset at which rotate the camera to reach an intermediate position. Similarly, the coordinates of the target position relative to the intermediate position will be (1,1).

Previously, get the target position (Pan, Tilt). Next, one intermediate position is determined (Pan - G, Tilt - G), after which the camera is rotated at maximum speed from the initial position to the intermediate. From the intermediate position, turn the camera to the target position with minimal speed.

The result of this sequence of actions will be a reduction in positioning error at the target point, since the movement into it was carried out at a minimum speed. At the same time, the positioning time will increase insignificantly, since with a minimum speed the camera moved only a short interval of the positioning trajectory, namely, the path of one degree along the panoramic angle and tilt angle. In addition, the direction of the reduced error will be the same, since the camera’s vector of movement at the moment of reaching the target position will be the same, which will allow translating the error into a systematic category, taking into account and thus completely leveling.

In an example implementation with two intermediate points, the target position is first obtained, after which two intermediate positions are determined. The first position (Pan - 1 °, Tilt - 1 °), the second position (Pan, Tilt - 1 °). Then they are positioned in the first intermediate position with maximum speed, after which they are positioned in the second intermediate position with minimum speed. As a result, they are positioned at the target position with minimal speed.

One skilled in the art will appreciate that the technical result is achieved using one intermediate point. As the number of intermediate points increases, the positioning error decreases.

In addition to the technical result described for the method with one intermediate point, this device results in a further reduction in positioning error due to the fact that in the last two steps the movement is carried out only in one of the angles and there is no error associated with inaccurate synchronization of the positioning mechanism drives movement along each of the corners.

The present detailed description is made up of various non-limiting and exhaustive embodiments. At the same time, for specialists having an average level of competence in the considered field of technology, it is obvious that various replacements, modifications or combinations of any of the embodiments disclosed herein (including partially) can be reproduced within the scope of this technical solution. Thus, it is understood and understood that the present description of the technical solution includes additional embodiments, the essence of which is not set forth here in an explicit form. Such embodiments may be obtained by, for example, combining, modifying, or transforming any actions, components, elements, properties, aspects, characteristics, limitations, etc., related to the embodiments presented here and not having a restrictive character.

USED SOURCES

1. “Keeping a Pan-Tilt-Zoom Camera Calibrated)), authors: Ziyan Wu, Richard J.

Radke, published by: IEEE Trans. Pattern Anal. Mach. Intell - 2013.

2. S. N. Sinha and M. Pollefeys. Pan-tilt-zoom camera calibration and high-resolution mosaic generation. Computer Vision and Image Understanding, 103 (3): 170-183, Sept. 2006.

3. M. Sarkis, C. Senft, and K. Diepold. Calibrating an Automatic Zoom Camera With Moving Least Squares. IEEE Transactions on Automation Science and Engineering, 6 (3): 492-503, July 2009.

4. Internet resource: http.7 / www.aktivsb.ru / article-info 1052.html

5. Computer vision, a modern approach Computer Vision: A Modern Approach Authors: David A. Forsyth, Jean Pons Translators: A. Nazarenko, I. Doroshenko Languages: Russian Publisher: William ISBN 5-8459-0542-7, 0-13-085198 -one; 2004 year

6. Strongin R.G. Numerical methods in multiextremal problems.

"Optimization and investigation of operations", The main edition of the physical and mathematical literature of the publishing house "Science", M., 1978, 240 pp.

7. Papadimitriou X., Steiglitz K. Combinatorial optimization: Algorithms and complexity. M .: Mir, 1985

8. Batishchev D. I. Genetic algorithms for solving extreme problems. Ed.

Lvovich Ya.E .: Textbook. allowance. Voronezh, 1995, 64 p.

9. Internet resource: https://ru.wikipedia.Org/wiki/y gley Euler

Claims

FOPMYJIA

1. A device for reducing the positioning error of a PTZ camera, includes:

• ΡΤΖ-camera;

• data processing unit;

• data storage unit;

• program

i. where the program is stored on a data storage unit and executed on a data processing unit, the program including the following instructions:

the processing unit receives the target position of rotation of the камеры-camera;

the command processing unit determines at least one intermediate position of the camera and its coordinates based on the target rotation position of the camera;

the command processing unit sends the command to the ΡΤΖ-camera

sequentially turning to the target position through the aforementioned intermediate positions.

2. The device for reducing the positioning error of a PTZ camera according to claim 1, in which the data processing unit includes an instruction receiving unit and a control unit configured to display information in the data output unit.

3. The device for reducing the positioning error of the PTZ camera according to claim 1, in which the command processing unit receives the target rotation position of the камеры-camera from the data block or input block.

4. The device for reducing the positioning error of a PTZ camera according to claim 1, in which at least one intermediate position and its coordinates are determined by testing the camera.

5. The device for reducing the positioning error of a PTZ camera according to claim 1, in which at least one intermediate position and its coordinates are determined based on ideas about the method of operation and the characteristics of the rotary mechanism of the camera.

6. The device for reducing the positioning error of a PTZ camera according to claim 1, in which the intermediate points can be determined through absolute coordinates or through relative coordinates.

7. The device for reducing the positioning error of a PTZ camera according to claim 1, in which the number and coordinates of intermediate positions depend on the required speed and positioning accuracy.

8. The device for reducing the positioning error of the PTZ camera according to claim 1, in which the relative coordinates of the intermediate position are determined so that the intermediate position is as close to the desired position.

9. The device for reducing the positioning error of a PTZ camera according to claim 1, wherein computer vision algorithms are used to determine the positioning error.

10. The device for reducing the positioning error of the PTZ camera according to claim 1, wherein at least two intermediate positions are determined, the first position being different by A in the panoramic angle and the angle of inclination from the desired position, and the second intermediate position in the panoramic angle is the same as required position, and the angle of inclination differs by A.

11. The device for reducing the positioning error of a PTZ camera according to claim 1, wherein at least two intermediate positions are determined, the first position being different by A in the panoramic angle and the angle of inclination from the desired position, and the second intermediate position in the angle of inclination coincides with required position, and in panoramic angle differs by A.

12. The device for reducing the positioning error of the PTZ camera according to claim 1, in which the speed of movement from the starting point to the first intermediate, between the intermediate and between the last intermediate point and the target point can be different.