Patent Application
20210389423
The invention relates to a method for distinguishing, detecting and counting persons and/or objects in facilities and/or vehicles for conveying persons and/or goods, with the following method steps: emitting radiation from a radiation source, deflecting the radiation with an element for deflecting the radiation, generating a light pattern in a detection region, and detecting the radiation backscattered by persons and/or objects situated in the detection region in a radiation detector, as well as a corresponding person and/or object counting device.
Guiding flows of people, in particular in urban environments requires an exact detection and a predictive analysis of the passenger flows. For this purpose, the persons getting into the vehicle (in particular bus, train, etc.) and getting out of the vehicle and the objects they may be carrying with them (suitcase, bicycle, etc.) must be exactly and reliably detected and classified. For this purpose, already known methods and sensors are employed in the environments mentioned.
A known solution uses multiple sensors at a distance of approx. 30 cm. Entering and exiting persons are counted by triangulation in the sensor. The counting events per pass are aggregated in a separate evaluation unit.
Another solution uses a counting sensor based on the time-of-flight (ToF) principle. Here, a region to be monitored is illuminated with a short modulated light pulse. A photonic mixer device evaluates the signal time of flight and provides signals that have a direct reference to 3D information. Counting data are generated from the algorithmic treatment of the 3D data.
Another known solution evaluates the intensity of the light reflected by persons and objects. Another employed solution uses two cameras which evaluate a stereoscopic image of the persons and objects. Another solution uses a counting sensor which actively works stereoscopicaliy, i.e. uses a light source in addition to the stereo camera.
The systems and methods mentioned here have various disadvantages. Using multiple sensors is complex, therefore expensive and, due to their dimensions, cannot be integrated into every environment that should be monitored. The use of a short modulated light pulse requires a high energy content of the pulse in order to illuminate the region to be monitored sufficiently strongly so that a sufficient reflected brightness is available for the exposure of the PMD chip. This means the sensor consumes a lot of energy. In particular the pulse characteristic in the electricity consumption must be managed with circuitry, in addition, due to the finite efficiency of the light sources, a considerable amount of heat energy is created. This makes complex thermal management necessary.
The detection of the reflection of the emitted light is dependent on the material of the reflector. Due to different clothing and hair, persons are very different in their reflection of light. With known devices, evaluating only light intensities due to reflection can lead to unreliable counting results.
Due to their principle, stereoscopic cameras are reliant on identifying unique features when comparing the two corresponding images. Usually, contrasts in the image that are caused by edges or outlines are used as a feature. If a scene is low contrast, this can lead to problems in the calculation of depth data. Too little ambient light or persons who blend in optically with the environment due to their clothing can be causes of lacking contrast. A lack of correct depth data can lead to erroneous counting.
Using light sources for large-area illumination of the region to be monitored can solve the problem of too little ambient light in the case of stereo cameras. The problem of low contrast in specific scenes is not solved by this.
It is therefore an object of the present invention to provide a method with which entering and exiting persons and objects can be counted exactly, reliably and in a cost-effective manner under the typical ambient conditions in the mobile field, in particular in the field of public passenger transportation. It is also an object of the present invention to provide a device with which entering and exiting persons and objects can be counted exactly, reliably and in a cost-effective manner under the typical ambient conditions in the mobile field, in particular in the field of public passenger transportation.
The object is solved by the method according to claim 1. Further advantageous embodiments of the invention are set out in the dependent claims.
The method according to the invention for distinguishing, detecting and counting persons and/or objects in facilities and/or vehicles for conveying persons and/or goods has four method steps: In the first method step, a radiation source emits radiation. The ambient light can contain sunlight or light from artificial illumination sources. It is therefore to be expected that radiation from the near infrared wavelength range is contained in the ambient light. Such ambient light can overlay the light that is emitted. As a solution, continuously radiated monochromatic light is used. The wavelength is chosen such that it is remote from the maximum of the spectral radiation strength of the sun and common artificial light sources, but at the same time can still be received by affordable silicon-based detectors. Additionally, it is required that the radiation be invisible to the human eye. For the realization of the invention, light of the wavelength from 780 nm to 1000 nm is suitable. When using a spectrally selective detector, the invention works reliably under the ambient conditions in the mobile range. Monochromatic light is typically used.
In the second method step, the radiation is deflected by an element for deflecting the radiation. The radiation is collimated by a lens and guided vertically onto a diffractive optical element (DOE). DOEs have some advantages over beam shaping by, for example, masks. Beam parts with an intensity that is too low are not simply suppressed by a mask, but rather, due to the principle, the intensity of the beam is limited only by the diffraction efficiency of the diffractive structure. As a result, the beam energy can be taken advantage of efficiently.
In the third method step, a light pattern is generated in a detection region. The DOE is structured such that a suitable light pattern is created behind the DOE. In the context of the invention, any optical arrangement which generates a light pattern with the described properties can be used.
The projected light pattern consists of small, delimited, illuminated regions and of dark, i.e. non-illuminated, regions. The illuminated regions can be abstracted in a good approximation as light points. The location of the light points can be described assuming the model of light beams originating from a central projection point in the radiation source.
An important feature of the invention is the monitoring of a spatial region. The light of the light pattern projector falls from a central projection point into this spatial region. The radiation detector is oriented such that its spatial field of vision is largely identical to the illuminated spatial region. The common spatial region is the detection region of the device for detecting, categorizing and counting persons and/or objects.
The detection region is described by the spatial angle of the central projection. Depending on the choice of the aperture, the detection region is described by suitable geometric figures, the geometric origins of which lie in the central projection point of the device for detecting, categorizing and counting persons and/or objects. With a rectangular aperture, it is the pyramid with a rectangular and even outline; with a round aperture, it is the straight circular cone. The spatial angle of the straight circular cone is: Ω=4πsin2 (φ/4), wherein φ is the full beam angle. The spatial angle of the pyramid is: Ω=4 arcsin(sin(φx/2)sin(φy/2)), wherein φx and φy are the two full beam angles. For the use of the invention with the requirement of direction recognition, two light beams are sufficient. The two beams are slightly divergent from one another but detect predominantly the same spatial region. With this geometry, a spatial angle of at least Ω=0.006 sr can be detected. By using additional beams, the detection region can be extended up to the hemisphere. The spatial half below the plane of installation of the device for detecting, categorizing and counting persons and/or objects is then completely monitored; the spatial angle is 2πsr. To carry out the invention, it is sufficient to choose the detection region such that at least one part of the human body of a person and/or one part of an object is detected in the defined spatial region.
According to the invention, the beam density of the light pattern lies in this case in the range of 5*102/4*πsr−1≤ρs≤106/4*πsr−1. The density of the pattern points determines the resolution of the detected persons and objects. Since the pattern points are created through central projection, the number of the light beams per spatial angle is a measure for the resulting point density. The spatial angle Ω is defined as the area content A of a sub-area of a sphere surface, divided by the square of the radius r of the sphere Ω=A/r2. Here, the center point of the sphere lies in the central projection point. N is the number of light beams that fall into the detection region. These light beams penetrate a sphere surface with the radius 1 m and the spatial angle 4πsr. Thus, the beam density in the detection region of ρs=N/4πsr−1 results. In the simplest case, two light beams are sufficient for counting persons. The beam density is then ½πsr−1. In order to obtain more data, up to 106 points in the detection region can be used.
In the fourth method step, the radiation backscattered by persons and/or objects situated in the detection region is detected in a radiation detector.
Facilities and/or vehicles for conveying persons and/or goods in the context of this invention can be train stations, stops, ports, airports or parts or regions thereof, as well as buses, trains, metro trains, suburban trains, ships and aircraft as well as any other facility or part of a facility as well as vehicles of any type.
In a further embodiment of the invention, a light pattern is detected in the detection region. Each person and/or object situated in the detection region generates a different light pattern than the light pattern generated in the detection region. These light patterns generated by persons and/or objects when the individual light beams hit the respective persons and/or objects are detected.
In a further embodiment according to the invention, the light pattern carries a code which establishes uniqueness. This is ensured, for example, by a specific arrangement of the light points of the light pattern, in which each point of the light pattern has an environment (submatrix) of light points uniquely assigned to it.
In a further design of the invention, a movement of the light pattern is detected in the detection region. The imaginary line between the optical axis of the radiation source and the optical axis of the radiation detector is referred to as the baseline. If a person enters the detection region over time, the radiation detector observes a movement of parts of the generated light pattern along the baseline.
In a further embodiment of the invention, a shift of the light pattern is detected in the detection region. The detected light patterns are compared with the projected light pattern. For small image regions which have experienced a shift in relation to the generated light pattern, a shift is detected.
In a further embodiment of the invention, the length of the shift is calculated. The detected light patterns are compared with the projected light pattern. For small image regions which have experienced a shift in relation to the generated light pattern, a shift is detected and its length calculated.
In a further embodiment of the invention, a depth value is determined from the length of the shift. A depth value can be calculated for a small image region from the length shift on the basis of the geometric relationships. A 3D point cloud for further evaluation is provided as the result. Information about the scene in the detection region, including persons and objects present, is represented by the depth values of the 3D point cloud. Persons or objects have a characteristic, three-dimensional shape in space.
In a further design of the invention, the detected, synchronously shifted light patterns are compared with characteristic known patterns. The known patterns are, for example, stored in a memory, The synchronously shifted detected light patterns are compared with these known patterns in order to identify whether the synchronously shifted detected light patterns are persons and/or objects.
In a further embodiment of the invention, the light pattern is assigned to an object type. An object type is, for example, a person or a body part of a person, for example the face, or also an object such as, for example, a suitcase, bicycle, etc.
In a further embodiment of the invention, a characteristic point is determined for the assigned light pattern. The characteristic point computationally represents the synchronously shifted light pattern. In a further aspect of the invention, the characteristic point is determined with the aid of the center of gravity method.
In a further design of the invention, a counting event is triggered when the light pattern and/or the characteristic point touches a counting region. Over time, a series of such characteristic points, which form a trajectory with a known directional progression, are created by evaluating many data. If the trajectory intersects the counting region, a counting event is generated.
In a further embodiment of the invention, the counting region comprises a volume which is defined in space and is at least partially part of the detection region. The counting region can be a volume that is part of the detection region.
In a further aspect of the invention, the counting region comprises an area which is defined in space and intersects the detection region. Location and extension of the counting area are variable and can be adapted to the spatial conditions. If, for example, the passage through a door portal (entrance) is to be monitored, the counting area can be defined as a plane or area running parallel to the portal opening.
In the context of this invention, the counting region is a defined area or a defined space and part of the detection region. It can be defined, for example, as an area or space within an entrance to a facility or a building, or a vehicle for conveying persons and/or goods. According to the invention, the counting region then lies 30 cm in front of to 30 cm behind the opening of the entrance or door portal. In the general case of curved door portal areas and a curved counting region, the distance refers to the shortest distance between area and region. Moving persons and/or objects must completely pass through the counting region in order to trigger a counting event. In this manner, it is avoided that a counting event is generated despite the fact that the person or the object does not enter the facility or the vehicle at all because they, for example, only want to ascertain if a seat is free and during this process come into contact with the counting region.
In a further embodiment of the invention, the direction of movement of the light pattern and/or of the characteristic point is detected. Through this embodiment, it can be recognized whether a person and/or the object enters or exits the facility and/or the vehicle.
In a further embodiment of the invention, the counting event is classified using the direction of movement of the light pattern and/or of the characteristic point. If many persons and/or objects enter the facility and/or the vehicle, the counting event can be classified, for example, in regard to an imminent overfilling of the vehicle. Underutilization can also be detected in this manner, the user obtains statistical data about the capacity utilization or the use of the facility and/or of the vehicle over a period of time of any desired length.
In a further design of the invention, the method is suitable for distinguishing, detecting and counting persons and objects in facilities and/or vehicles for conveying persons and/or goods.
In a further embodiment of the invention, the beam density ρs is at least 1*103/4*πsr−1, preferably 5*103/4πsr−land particularly preferably 1*104/4*πsr−1. The point density of the generated light pattern is to be chosen such that the generated light pattern in small image sections along the direction of shift of the persons and/or objects is unique at any possible position. At the same time, in contrast, the generated data volume should be as low as possible.
It has been shown that, for typical operation in vehicles for conveying persons and/or goods, the most favorable point density of the light pattern is one that corresponds to a beam density ρs of at least 1*103/4*πsr−1 and particularly preferably 1*104/4*πsr−1, depending on the distance of the persons and objects to be detected or of the detection region.
In a further embodiment of the invention, the beam density ρs is maximally 5*105/4*πsr−1, preferably 1*105/4*πsr−1 and particularly preferably 5*104/4*πsr−1. The point density of the generated light pattern is to be chosen such that the generated light pattern in small image sections along the direction of shift of the persons and/or objects is unique at any possible position. At the same time, in contrast, the generated data volume should be as low as possible. It has been shown that, for typical operation in vehicles for conveying persons and/or goods, the most favorable point density of the light pattern is one that corresponds to a beam density ρs of maximally 1*105/4*πsr−1 and particularly preferably 5*104/4*πsr−1, depending on the distance of the persons and objects to be detected or of the detection region.
The object is also solved by the device according to claim 19. Further advantageous embodiments of the invention are set out in the dependent claims.
The device according to the invention for detecting, categorizing and counting persons and/or objects in facilities and/or vehicles for conveying persons and/or objects has a radiation source, a radiation detector and an element for deflecting the radiation leaving the radiation source.
The radiation source generates continuous monochromatic laser radiation with a wavelength in the range from 780 nm to 1000 nm. According to the invention, the element for deflecting the radiation leaving the radiation source is configured such that it is suitable for generating a light pattern in a detection region with a beam density of 5*102/4*πsr−1≤ρs≤106/4*πsr−1. The projected light pattern consists of small, delimited, illuminated regions and of dark, i.e. non-illuminated, regions. The illuminated regions can be abstracted in a good approximation as light points. The location of the light points can be described assuming the model of light beams originating from a central projection point in the radiation source.
An important feature of the invention is the monitoring of a spatial region. The light of the light pattern projector falls from a central projection point into this spatial region. The radiation detector is oriented such that its spatial field of vision is largely identical to the illuminated spatial region. The common spatial region is the detection region of the device for detecting, categorizing and counting persons and/or objects.
The radiation source and optical elements generate the desired light pattern to be projected. One possible embodiment uses a laser diode as the radiation source, a collimator lens and a diffractive optical element (DOE). Along with the objective and the bandpass filter, the image sensor forms the radiation detector.
In a further aspect of the invention, the device for detecting, categorizing and counting persons and/or objects has an interface to a control and/or evaluation unit.
In a further embodiment of the invention, the device for detecting, categorizing and counting persons and/or objects has a control and/or evaluation unit. The control and evaluation unit has a memory as well as a computing unit.
In a further design of the invention, the radiation detector is suitable for detecting radiation of the light pattern backscattered by persons and/or objects in the detection region. A bandpass filter installed in the radiation detector is only permeable to light in a narrow spectral window. The central wavelength of the bandpass filter corresponds to the wavelength of the light emitted by the radiation source. This prevents light of other wavelengths from exposing the image sensor. By using the radiation source, the device for detecting, categorizing and counting persons and/or objects actively provides light and can also work in dark environments.
In a further embodiment of the invention, the control and/or evaluation unit is suitable for executing a program which assigns an object type to the light patterns on the basis of the light patterns backscattered by the persons and/or objects in the detection region. An object type is, for example, a person or a body part of a person, for example the face, or also an object such as, for example, a suitcase, bicycle, etc.
In a further embodiment of the invention, the control and/or evaluation unit is suitable for executing a program which follows the shift of persons and/or objects with regard to their direction and/or length on the basis of the backscattered light patterns.
Information about the scene in the detection region, including persons and objects present, is represented by the depth values of the 3D point cloud. Persons or objects have a characteristic, three-dimensional shape in space. A suitable program, for example a recognition algorithm, searches for parts of such more characteristic shapes in the data of the 3D point cloud. If there is a match, a shape is detected. The position of a specific person or of a specific object can be abstracted by means of a characteristic point, which is determined, for example, by means of the center of gravity method.
Over time, a series of such characteristic points, which form a trajectory with a known directional progression, is created by evaluating many data from the radiation detector. From the direction of the trajectory it can be determined whether the person is getting into the vehicle or getting out of the vehicle, or is entering or exiting the facility. The same principle can be applied for objects, for example for bicycles or suitcases, that are brought into the detection region.
In a further embodiment of the invention, the device for detecting, categorizing and counting persons and/or objects is suitable for detecting the touching of a light pattern with a counting region situated in the detection region. Information about the scene in the detection region, including persons and objects present, is represented by the depth values of the 3D point cloud. The position of a specific person or of a specific object can be abstracted by means of a characteristic point, which is determined, for example, by means of the center of gravity method. If the trajectory intersects a predefined area in the space, the counting region, a counting event is generated.
in a further embodiment of the invention, the counting region comprises a volume, the location of which is predefined. In a further aspect of the invention, the counting region comprises a plane, the location of which is predefined. Location and extension of the counting area are variable and can be adapted to the spatial conditions. If, for example, the passage through a door portal is to be monitored, the counting area can be defined as a plane running parallel to the portal opening.
In a development of the invention, the counting region comprises at least two planes, the location of which is predefined. Location and extension of the counting areas are variable and can be adapted to the spatial conditions. Typically, two counting areas arranged parallel to one another are used. The person or the object must then move at least partially through one counting area and also at least partially penetrate the second area again with a time delay. A counting event is only triggered once the resulting passage is detected.
In a further design of the invention, the counting region is arranged in a region between 30 cm in front of and 30 cm behind the entrance of the facility and/or of the vehicle for conveying persons and/or objects.
In a further aspect of the invention, the counting region is arranged in a region between 20 cm in front of and 20 cm behind the entrance of the facility and/or of the vehicle for conveying persons and/or objects and preferably in a region between 10 cm in front of and 10 cm behind the entrance of the facility and/or of the vehicle for conveying persons and/or objects.
In a further embodiment of the invention, the generated beam density ρs is at least 1*10/4*πsr−1, preferably 5*103/4*πsr−1 and particularly preferably 1*104/4*πsr−1. The point density of the generated light pattern is to be chosen such that the generated light pattern in small image sections along the direction of shift of the persons and/or objects is unique at any possible position. At the same time, in contrast, the generated data volume should be as low as possible.
It has been shown that, for typical operation in vehicles for conveying persons and/or goods, the most favorable point density of the light pattern is one that corresponds to a beam density ρs of at least 1*103/4*πsr−1 and particularly preferably 1*104/4*πsr−1, depending on the distance of the persons and objects to be detected or of the detection region.
In a further embodiment of the invention, the generated beam density ρs is maximally 5*105/4*πsr−1, preferably 1*105/4*πsr−1 and particularly preferably 5*104/4*πsr−1. The point density of the generated light pattern is to be chosen such that the generated light pattern in small image sections along the direction of shift of the persons and/or objects is unique at any possible position. At the same time, in contrast, the generated data volume should be as low as possible. It has been shown that, for typical operation in vehicles for conveying persons and/or goods, the most favorable point density of the light pattern is one that corresponds to a beam density ρs of maximally 1*105/4*πsr−1 and particularly preferabiy 5*104/4*πsr−1, depending on the distance of the persons and objects to be detected or of the detection region.
Exemplary embodiments of the method according to the invention for distinguishing, detecting and counting persons and/or objects in facilities and/or vehicles for conveying persons and/or goods and the device according to the invention for detecting, categorizing and counting persons and/or objects in facilities and/or vehicles for conveying persons and/or objects are shown schematically simplified in the drawings and are explained in greater detail in the following description.
The device for detecting, categorizing and counting persons and/or objects 1 has a radiation source 10, an element for deflecting the radiation 30, and a radiation detector 20. In addition, an electronic control and evaluation apparatus 60 is installed in or within communication range of the device for detecting, categorizing and counting persons and/or objects 1, which are connected to one another by means of interfaces 70.
The device for detecting, categorizing and counting persons and/or objects 1 is situated, in all the exemplary embodiments shown here, in the upper region of the region for getting into and getting out of the vehicle.
To describe the location of the device for detecting, categorizing and counting persons and/or objects 1 in space, the central projection point of the radiation source 10 is used and the location of the optical axis of the radiation source 10, meaning the straight line which is perpendicular to the element for deflecting the radiation 30 and contains the central projections point. If the elements of the device for detecting, categorizing and counting persons and/or objects 1 are firmly connected to one another, the geometric location of the device for detecting, categorizing and counting persons and/or objects 1 is thus also clearly defined in space. In order to ensure the functionality of the device for detecting, categorizing and counting persons and/or objects 1, the projection point lies between 1.7 m (minimum) and 20 m (maximum) vertically above the floor of the vehicle. In typical vehicles, the projection point lies between 1.8 m to 3 m vertically above the floor of the vehicle.
To distinguish, detect and count persons and/or objects in vehicles for conveying persons and/or goods, the radiation source 10 of the device for detecting, categorizing and counting persons and/or objects 1 emits radiation S in the first method step. The ambient light can contain sunlight or light from artificial illumination sources. It is therefore to be expected that radiation from the near infrared wavelength range is contained in the ambient light. Such ambient light can overlay the light that is emitted by the radiation source 10. As a solution, monochromatic laser radiation and a spectrally selective detector is used. The wavelength is chosen such that the radiation is invisible to the human eye. When choosing the wavelength, it must be ensured that the image sensor of the radiation detector 20 has a sufficiently high quantum efficiency to generate enough photoelectrons. For the realization of the invention, light of the wavelength from 780 nm to 1000 nm is suitable. The invention thus works reliably under the ambient conditions in the mobile range.
The laser radiation S is collimated by a lens and guided perpendicularly onto the element for deflecting the radiation 30. The element for deflecting the radiation 30 is usually a diffractive optical element (DOE), which is structured such that, in the second method step for distinguishing, detecting and counting persons and/or objects in vehicles for conveying persons and/or goods, a suitable detection region 40 having a counting area 80 is created behind the DOE 30. In the context of the invention, however, any optical arrangement which generates a light pattern 50 can also be used. In this exemplary embodiment, the counting area 80 is chosen such that it coincides with the door cut-out of the region for getting in and getting out.
The device for detecting, categorizing and counting persons and/or objects 1 has a radiation source 10, an element for deflecting the radiation 30, and a radiation detector 20. In addition, an electronic control and evaluation apparatus 60 is installed in or within communication range of the device for detecting, categorizing and counting persons and/or objects 1, which are connected to one another by means of interfaces 70. The radiation source 10 generates continuous monochromatic laser radiation S with a wavelength in the range from 780 nm to 1000 nm.
In the third method step for distinguishing, detecting and counting persons and/or objects in facilities and/or vehicles for conveying persons and/or goods, the device for detecting, categorizing and counting persons and/or objects 1 generates a light pattern 50. The projected light pattern 50 consists of small, delimited, illuminated regions and of dark, i.e. non-illuminated, regions. The illuminated regions can be abstracted in a good approximation as light points. The location of the light points can be described assuming the model of light beams originating from a central projection point in the radiation source 10.
The generation of 3D depth data from a spatial region is central to the invention. In order to obtain such 3D data, the triangulation principle is expanded into the third spatial dimension. In order to obtain clear depth data, the correspondence problem between features of the detected images from the radiation detector 20 and the features that are projected into the space must be solved. The light pattern 50 provides the features required to solve the correspondence problem.
The light pattern 50 is designed in this case such that the projected light pattern 50 in small image sections along the direction of shift of the persons and/or objects is unique at any possible position.
The density of the pattern points determines the resolution of the detected persons and objects. Since the pattern points are created through central projection, the number of the light beams per spatial angle is a measure for the resulting point density. The spatial angle Ω is defined as the area content A of a sub-area of a sphere surface, divided by the square of the radius r of the sphere Ω=A/r2. Here, the center point of the sphere lies in the central projection point. N is the number of light beams that fall into the detection region. These light beams penetrate a sphere surface with the radius 1 m and the spatial angle 4πsr. Thus, the beam density in the detection region 40 of ρs=N/4πsr−1 results. In the simplest case, two light beams are sufficient for counting persons. The beam density is then ½sr−1. In order to obtain more data, up to 106 points in the detection region 40 can be used. The beam density is then 106/4πsr−1.
The light pattern has a code which establishes uniqueness. This is ensured here by a specific arrangement of the light points of the light pattern, in which each point of the light pattern has an environment (submatrix) of light points uniquely assigned to it.
In the fourth method step for distinguishing, detecting and counting persons and/or objects in facilities and/or vehicles for conveying persons and/or goods, the backscattered radiation from persons and/or objects situated in the detection region 40 is detected in the radiation detector 20. The imaginary line between the optical axis of the radiation source 10 and the optical axis of the radiation detector 20 is referred to as the baseline. If a person enters the detection region 40 over time, the radiation detector 20 observes a shift of parts of the light pattern 50 along the baseline. The program that is executed on the control and evaluation apparatus 60 compares the detected images from the radiation detector 20 with the projected light patterns 50. For small image regions which have experienced a shift in relation to the known light pattern 50, the program calculates the length of the shift, known as the disparity. Since the light pattern 50 on small image regions along the baseline is unique, exactly one disparity is found for each image region. A depth value can be calculated for a small image region from the disparity on the basis of the geometric relationships. In the result, a 3D point cloud is now provided for further evaluation. Optionally, a coded light pattern (see
Information about the scene in the detection region 40, including persons and objects present, is represented by the depth values of the 3D point cloud (
Over time, a series of such characteristic points, which form a trajectory with a known directional progression (
It has been shown that, for typical operation in vehicles for conveying persons and/or goods, the most favorable point density of the light pattern 50 is one that corresponds to a beam density ρs of at least 1*103/4πsr−1 and maximally 5*100/4*πsr−1, depending on the distance of the device for detecting, categorizing and counting persons and/or objects 1 from the persons and objects to be detected or the detection region 40. Illustrations of these point densities of the light pattern 50 are shown in
The device for detecting, categorizing and counting persons and/or objects 1 has a radiation source 10, an element for deflecting the radiation 30, and a radiation detector 20. In addition, an electronic control and evaluation apparatus 60 is installed in or within communication range of the device for detecting, categorizing and counting persons and/or objects 1, which are connected to one another by means of interfaces 70. The radiation source 10 generates continuous monochromatic laser radiation S with a wavelength in the range from 780 nm to 1000 nm.
An important feature of the invention is the monitoring of a spatial region. The light of the light pattern projector 100 falls from a central projection point into this spatial region. The radiation detector 20 is oriented such that its spatial field of vision is largely identical to the illuminated spatial region. The common spatial region is the detection region 40 of the device for detecting, categorizing and counting persons and/or objects 1.
The detection region 40 is described by the spatial angle of the central projection, Depending on the choice of the aperture, the detection region 40 is described by suitable geometric figures, the geometric origins of which lie in the central projection point of the device for detecting, categorizing and counting persons and/or objects 1, With a rectangular aperture, it is the pyramid with a rectangular and even outline; with a round aperture, it is the straight circular cone. The spatial angle of the straight circular cone is: Ω=4πsin2(φ/4), wherein φ is the full beam angle. The spatial angle of the pyramid is: Ω=4 arcsin(sin(φx/2) sin(φy/2)), wherein φx and φy are the two full beam angles. For the use of the invention with the requirement of direction recognition, two light beams are sufficient. The two beams are slightly divergent from one another but detect predominantly the same spatial region. With this geometry, a spatial angle of at least Ω=0.006 sr can be detected. By using additional beams, the detection region 40 can be extended up to the hemisphere. The spatial half below the plane of installation of the device for detecting, categorizing and counting persons and/or objects 1 is then completely monitored; the spatial angle is 2πsr. To carry out the invention, it is sufficient to choose the detection region 40 such that at least one part of the human body of a person and/or one part of an object is detected in the defined spatial region.
The orientation and location of the counting areas 80, 81 or of the counting volume 90 is shown in
A counting area 80 is a defined area in the detection region 40 (
In order to increase the reliability of the counting, two (
Along with the objective 110 and the bandpass filter 120, the image sensor 130 forms the radiation detector 20. The bandpass filter 120 is only permeable to light in a narrow spectral window. The central wavelength of the bandpass filter 120 corresponds to the wavelength of the light emitted by the radiation source 10. This prevents light of other wavelengths from exposing the image sensor 130. The image data are processed by the control and evaluation apparatus 80 and evaluated by means of a suitable program. The device for detecting, categorizing and counting persons and/or objects 1 is connected for this purpose via an interface 70 to the control and evaluation apparatus 60. The carrier structure 140 brings the radiation detector 20 and the light pattern projector 100 into a defined position and thus realizes what is known as the baseline.
By using the light pattern projector 100, the device for detecting, categorizing and counting persons and/or objects 1 actively provides light and can also work in dark environments. Since the illumination is not over a large area, but rather only light is guided in pattern regions, a smaller light power is necessary than with large-area illumination. Accordingly, less energy is consumed and less waste heat is created.
| Number | Date | Country | Kind |
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| 10 2018 128 013.0 | Nov 2018 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2019/080764 | 11/8/2019 | WO | 00 |
