JP7778425B2 - Event signal acquisition method for event-based vision cameras - Google Patents

Description

The present invention relates to a method for obtaining an event signal output by an event-based vision camera when it detects a change in brightness.

Machine vision, which captures and processes images to ensure proper equipment operation, is used in a variety of industrial applications, from security applications such as surveillance to automatic inspection and process control. Accurately capturing movement information is particularly important in machine vision, but conventional frame-based sensors must handle information from all pixels in a captured video frame, resulting in large amounts of data. This creates processing delays due to data transfer, making real-time processing difficult and placing a heavy processing burden on the image processing device. In contrast, event-based vision sensors asynchronously output only pixel information for which there is a change in brightness within the image, at the time the change occurs. This reduces data volume and enables highly efficient capture of only the movement information required for machine vision.

Event-based vision sensors are widely known, which asynchronously output event signals (e.g., data signals containing pixel brightness change information, pixel position coordinates, and the time the brightness change was detected) from pixels that detect brightness changes caused by the movement of a subject in the shooting area or changes in the surrounding environment. Event-based vision sensors only acquire instantaneous information for each pixel that captures a brightness change, and various processing steps are performed on the event signals to recognize moving objects in the shooting area and capture their movement. For example, an information processing method has been proposed that performs a process of grouping events identified by event signals from a device equipped with an event-based vision sensor (an event-based vision camera) according to connectivity criteria, thereby extracting the features of objects, etc. with high accuracy (see, for example, Patent Document 1).

Special Publication No. 2022-523505

However, although the event-based vision camera described in Patent Document 1 is configured to receive incident signals from the imaging area through an acquisition optical system (such as a telephoto lens) equipped with one or more lenses, no consideration is given to focus adjustment of the acquisition optical system. In other words, like a regular camera, an event-based vision sensor also requires focus adjustment of the optical system depending on the shooting distance from the subject, but if the subject is stationary, it is difficult to adjust the focus of the event-based vision camera before capturing an image.

In the first place, an event-based vision camera asynchronously outputs an event signal from pixels that detect changes in brightness caused by the movement of a subject in the shooting area or changes in the surrounding environment. If the subject is stationary and there are no changes in the surrounding environment, no event signal will be output from the event-based vision sensor. Naturally, if the event-based vision camera cannot obtain an event signal, it will not be able to check the image of the shooting area and therefore will not be able to adjust the focus.

If there is a constantly moving subject or a constantly changing surrounding environment within the shooting area, an event signal will be output due to changes in brightness caused by the subject's movement or changes in the surrounding environment, and the image of the shooting area can be confirmed, making it possible to adjust the focus of the optical system according to the shooting distance. Therefore, one possible method is to forcibly cause a brightness change (to generate an event) by forcing the subject to move by vibrating the subject, or by displaying an image with brightness changes on a display installed near the target. In this way, if a vibrating subject or a flickering display is photographed with an event-based vision camera, the image of the subject or display can be confirmed, making it possible to adjust the focus of the optical system according to the shooting distance.

However, the method of triggering an event by applying vibration to the subject to be photographed carries the risk of the subject shifting position and leaving the photographed area, or of the subject being physically damaged, making it an undesirable method. Furthermore, the method of triggering an event using a flickering display requires the effort and cost of procuring the display, as well as the additional time and cost required for running power and communication lines, making it an undesirable method either. To begin with, if the photographed area is so far away that it must be photographed with a telephoto lens from the event-based vision camera, or if the photographed area is so high up that it is difficult to work in, applying vibration to the subject or installing a display is itself difficult.

Therefore, the present invention aims to provide a method for acquiring an event signal from an event-based vision camera whose shooting area is a stationary subject or an unchanging surrounding environment.

In order to solve the above-mentioned problems, the present invention provides an event signal acquisition method for an event-based vision camera equipped with an event-based vision sensor that asynchronously outputs an event signal from pixels that detect changes in brightness caused by the movement of a subject in a shooting area or changes in the surrounding environment, and acquires the event signal in response to incident light from a motionless subject in the shooting area or from the unchanged surrounding environment. The method comprises the following steps: a first step of placing an event generation means between the event-based vision camera and the shooting area where the event-based vision camera receives the incident light; and a second step of using the event generation means to change over time the position of a shielding area that blocks the incident light from the shooting area and the position of a transparent area that transmits the incident light from the shooting area, thereby generating a change in brightness due to the change in the position of the shielding area and/or the change in position of the transparent area, and acquiring the event signal.

Furthermore, in the above configuration, the event generation means may include a slit body in which the transparent area is formed as a slit portion between each of the shielding materials by arranging a plurality of shielding materials at intervals to function as the shielding area, and may perform the first step of arranging the slit body so that the shielding material and the slit portion are simultaneously captured by the event-based vision camera, and may perform the second step of changing the position of the shielding area and the position of the transparent area over time by moving the slit body in an intersecting direction that intersects with the shooting direction of the event-based vision camera.

In addition, in the above configuration, the event generation means may be provided with a slit body drive mechanism that moves the slit body back and forth in the intersecting direction.

Furthermore, in the above configuration, the event generation means may support the slit body via an oscillating support that can oscillate the slit body in the intersecting direction.

Furthermore, in the above configuration, the event generation means may include a rotary slit body having a plurality of shielding sections formed radially from a center of rotation and functioning as the shielding areas, and slit sections formed between the plurality of shielding sections and functioning as the transparent areas, and the first step may be performed in which the shielding sections and the slit sections of the rotary slit body are positioned so that they are simultaneously captured by the event-based vision camera, and the second step may be performed in which the rotary slit body is rotated to change the positions of the shielding areas and the transparent areas over time.

In addition, in the above configuration, the event generation means may be provided with a rotary slit body rotation mechanism that rotates the rotary slit body at a constant speed in at least a constant direction.

Furthermore, in the above configuration, the event generation means may include a liquid crystal shutter that can be converted between a transparent state that transmits light and a blocking state that blocks light by adjusting the voltage applied to the liquid crystal cell, and may perform the first step of positioning the shutter surface of the liquid crystal shutter so that it blocks the shooting direction of the event-based vision camera, and the second step of changing the position of the blocking area and the position of the transparent area over time by alternately generating a state in which the shutter surface is in the blocking state so that the blocking area is positioned so that it blocks the shooting direction of the event-based vision camera, and a state in which the shutter surface is in the transparent state so that the transparent area is positioned so that it blocks the shooting direction of the event-based vision camera.

In addition, in the above configuration, the event generation means may be provided with an applied voltage control mechanism that controls the applied voltage so that the liquid crystal shutter repeatedly switches between the transparent and blocked states at regular intervals.

According to the event signal acquisition method for an event-based vision camera of the present invention, by performing the first and second steps, a change in brightness occurs due to a change in the position of the occluded area and/or a change in the position of the transparent area, making it possible to acquire an event signal from an event-based vision camera whose shooting area is a stationary subject or an unchanging surrounding environment.

FIG. 10 is a diagram illustrating a configuration in which a first event generating means consisting of a slit body and a slit body driving mechanism is disposed between an event-based vision camera and a photographing area. FIG. 4 is an explanatory diagram of a slit body driving mechanism. FIG. 10 is an explanatory diagram of the transition state of the imaging area visualized based on the event signal acquired from the event-based vision camera by the operation of the first event generating means. FIG. 10 is a diagram illustrating a configuration in which a second event generating means consisting of a slit body and a swingable support is disposed between the event-based vision camera and the photographing area. FIG. 10 is an explanatory diagram of the transition state of the imaging area visualized based on the event signal acquired from the event-based vision camera by the operation of the second event generating means. This is a configuration diagram in which a manually operable slit body is placed between an event-based vision camera and a shooting area. FIG. 10 is an explanatory diagram of the transition state of the imaging area visualized based on the event signal acquired from the event-based vision camera by manual operation of the slit body. FIG. 10 is a diagram illustrating a configuration in which a third event generating means consisting of a rotary slit body and a rotary slit body rotation mechanism is disposed between the event-based vision camera and the photographing area. FIG. FIG. 10 is an explanatory diagram of the transition state of the imaging area visualized based on the event signal acquired from the event-based vision camera by the operation of the third event generating means. This is a configuration diagram in which a fourth event generating means consisting of a liquid crystal shutter and an applied voltage control mechanism is placed between the event-based vision camera and the shooting area. FIG. 10 is an explanatory diagram of the transition state of the imaging area visualized based on the event signal acquired from the event-based vision camera by the operation of the fourth event generating means.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Figure 1 is a configuration diagram in which a first event generation means 2A consisting of a slit body 21 and a slit body drive mechanism 22 is placed between an event-based vision camera 1 and a photographing area PA. A subject 3, which is the subject of photographing by the event-based vision camera 1, is stationary and is placed, for example, within a photographing box 4 with a low-light interior so that it fits within the photographing area PA. The event signal ES output from the event-based vision camera 1 is input via a signal cable 5 to an information processing device 6 (e.g., configured by a personal computer executing a processing program). This information processing device 6 performs appropriate data processing to visualize the situation in the photographing area PA (e.g., moving objects or moving parts).

The event-based vision camera 1 includes an event-based vision sensor 1a that asynchronously outputs an event signal ES from pixels that detect brightness changes caused by the movement of the subject 3 in the imaging area PA or changes in the surrounding environment. The event signal ES is a data signal that includes pixel brightness change information, pixel position coordinates, and the time the brightness change was detected. It is output only from pixels that capture a change in the imaging area PA; no event signal ES is output from pixels that do not experience a change. The event-based vision camera 1 is also equipped with an optical system 1b, such as a telephoto lens, which requires focus adjustment according to the distance to the subject 3. However, since the subject 3 is stationary and there is no movement within the imaging box 4, which is the environment surrounding the subject 3, even if the event-based vision camera 1 captures the imaging area PA, the subject 3 and the surrounding environment cannot be confirmed, and therefore focus adjustment by the optical system 1b cannot be performed.

Here, we will explain a method for acquiring an event signal using an event-based vision camera 1 that receives incident light from a stationary subject 3 in the shooting area PA or from an unchanging surrounding environment and acquires an event signal ES.

The first step involves placing a first event generation means 2A between the event-based vision camera 1 and the imaging area PA where the event-based vision camera 1 receives incident light. As shown in Figure 2, the slit body 21 constituting the first event generation means 2A is formed by equally spaced shielding materials 212 that vertically block the inner space of a frame body 211 that surrounds all four sides. By arranging multiple shielding materials 212 that function as shielding areas at intervals, a transparent area is formed as a slit portion 213 between each shielding material 212. In the first step, the slit body 21 is positioned so that the shielding material 212 and the slit portion 213 of the slit body 21 are simultaneously captured by the event-based vision camera 1. For example, if the slit body 21 is positioned parallel to the imaging direction of the event-based vision camera 1, only the side of the frame body 211 of the slit body 21 will be captured, and the shielding material 212 and the slit portion 213 of the slit body 21 will not be simultaneously captured by the event-based vision camera 1. In other words, when the slit body 21 is positioned in the cross direction CD that intersects with the shooting direction of the event-based vision camera 1, the shielding material 212 and the slit portion 213 of the slit body 21 are positioned so that they are simultaneously captured by the event-based vision camera 1.

Next, a second step is performed in which the slit body drive mechanism 22 of the first event generation means 2A moves the slit body 21 in the cross direction CD that intersects the shooting direction of the event-based vision camera 1 so as to block the shooting direction of the event-based vision camera 1, thereby changing the position of the shielding material 212, which is the blocking area, and the position of the slit portion 213, which is the transparent area, over time. That is, in this second step, the position of the blocking area that blocks light incident from the shooting area PA to the event-based vision camera 1 and the position of the transparent area that transmits light incident from the shooting area PA to the event-based vision camera 1 are changed over time. Note that because the width of the slit body 21 cannot be made extremely long, moving the slit body 21 a fixed distance in the reference direction, then returning it a fixed distance in the opposite direction, and then moving it again a fixed distance in the reference direction, thereby continuously generating changes in the position of the blocking area and the position of the transparent area over time.

The configuration of the slit body drive mechanism 22 is not particularly limited, but for example, Figure 2 shows an example configuration in which the rotational power of the motor 221, which is the drive source, is converted into reciprocating motion of the slit body 21. A first interlocking belt 223 is wound around a drive pulley 221b attached to the motor shaft 221a of the motor 221 and the large diameter pulley portion 222a of the first pulley 222, so that when the motor 221 rotates, for example, clockwise, the first pulley 222 also rotates clockwise. A second interlocking belt 225 is wound around the small diameter pulley portion 222b of the first pulley 222 and the second pulley 224, so that when the first pulley 222 rotates clockwise, the second pulley 224 also rotates clockwise. One end of the connecting piece 226 is loosely fitted into a driving protrusion 224a protruding from one side of the second pulley 224, and the other end of the connecting piece 226 is loosely fitted into a driven protrusion 227a of the slide base 227. A first slide portion 227b1 on one side of the slide base 227 and a second slide portion 227b2 on the other side are guided by a guide rail 228 arranged parallel to the cross direction CD, and the movement direction of the slide base 227 is restricted to the cross direction CD. Therefore, the pushing and pulling of the connecting piece 226 accompanying the rotation of the second pulley 224 causes the slide base 227 to reciprocate in the cross direction CD, and the slit body 21 held by the slit body fixing portion 227c of this slide base 227 also reciprocates in the cross direction CD.

As described above, performing the first and second steps causes a change in brightness due to a change in the position of the shielded area and the position of the transparent area, so that an event signal ES can be acquired by the event-based vision camera 1, whose imaging area PA is an unmoving subject 3 and an unchanging surrounding environment. Therefore, the status of the imaging area PA, which is an unmoving subject 3 and an unchanging surrounding environment, can be confirmed, and the focus of the optical system 1b of the event-based vision camera 1 can also be adjusted.

Figure 3 shows the transition state of the imaging area PA visualized based on the event signal ES acquired from the event-based vision camera 1 by the operation of the first event generation means 2A. Without the second step performed by the first event generation means 2A, nothing would be visible in the imaging area PA. However, when the second step is performed by the first event generation means 2A, the subject 3 becomes visible through the slit portion 213 along with the shielding material 212 of the slit body 21. Once the status of the subject 3 can be confirmed, the focus of the optical system 1b can be adjusted to match the focal length to the subject 3. Note that if the brightness of the subject 3 and the surrounding environment is the same as the brightness of the slit body 21, the event-based vision sensor 1a will not be able to detect a clear change in brightness. Therefore, it is desirable to make the brightness of the subject 3 and the surrounding environment different from the brightness of the slit body 21. Because the interior of the imaging box 4 described above is relatively dark, a light color (e.g., white) for the slit body 21 allows the event-based vision sensor 1a to detect a clear change in brightness. The width, number, sliding period and vibration period of the shielding material 212 and slit portions 213 in the slit body 21 have optimum values depending on the distance to the subject, the size of the subject, the surrounding lighting conditions and the like.

While the first event generation means 2A described above uses a slit body drive mechanism 22 to perform the second step, it is also possible to generate an event (forcefully cause a change in brightness) using a simpler structure. Figure 4 shows second event generation means 2B, which is composed of a slit body 21 and a swinging support 23 that can swing the slit body 21 in the cross direction CD. The swinging support 23 has an elastic body 23a, such as a coil spring, leaf spring, or rubber material, whose lower part is fixed to a fixed plate 23b, and the upper part of the elastic body 23a supports the bottom of the slit body 21. In other words, the slit body 21, supported by the elastic body 23a, swings in front of the event-based vision camera 1 due to elastic deformation corresponding to the magnitude and direction of the force applied to the elastic body 23a.

When acquiring an event signal ES using this second event generating means 2B, the first step involves placing the second event generating means 2B between the event-based vision camera 1 and the image capture area PA, and the second step involves changing the positions of the shielded and transparent areas in the slit body 21 over time using the oscillating support 23. The oscillation of the slit body 21 causes changes in brightness due to changes in the positions of the shielded and transparent areas, allowing the event signal ES to be acquired by the event-based vision camera 1, whose image capture area PA is an unmoving subject 3 or an unchanging surrounding environment. This makes it possible to confirm the status of the unmoving subject 3 or the unchanging surrounding environment in the image capture area PA, and also makes it possible to adjust the focus of the optical system 1b of the event-based vision camera 1.

Figure 5 shows the transition state of the imaging area PA visualized based on the event signal ES acquired from the event-based vision camera 1 by the operation of the second event generation means 2B. In the second event generation means 2B, the amount of displacement increases the farther the part of the oscillating support 23 is from the elastic body 23a, so the frequency of detecting brightness changes increases in the part where the upper part of the slit body 21, which is farther from the elastic body 23a, is captured. As the frequency of detecting brightness changes by the event-based vision sensor 1a increases, more detailed event signals ES can be acquired, which contributes to the visualization of a clearer image. Therefore, when the subject 3 is located relatively high in the imaging area PA, acquiring the event signal ES using the second event generation means 2B is effective.

While the first and second event generation means 2A and 2B described above use a slit body drive mechanism 22 or a swinging support 23 to perform the second step, an event can also be generated more simply (by forcing a change in brightness). Figure 6 shows a configuration in which a slit body 21 is placed between the event-based vision camera 1 and the imaging area PA with a hand 7 and the slit body 21 is moved in the cross direction CD with the hand 7. Figure 7 shows the transition state of the imaging area PA visualized based on the event signal ES acquired from the event-based vision camera 1 as the slit body 21 is moved with the hand 7. Even when the slit body 21 is moved with the hand 7, the subject 3 in the imaging area PA is accurately captured.

Furthermore, while the first and second event initiation means 2A and 2B reciprocate the slit body 21 in the cross direction CD, this is not limited to this. The third event initiation means 2C is composed of a circular plate-shaped rotary slit body 24 and a rotary slit body rotation mechanism 25 that rotates the rotary slit body 24 at least in a fixed direction at a fixed speed, and the rotary slit body 24 performs the same function as the slit body 21.

An example of the rotary slit body 24 is shown in Figure 9. The rotary slit body 24 comprises a rotary base 241 having a rotary shaft mounting hole 241a serving as the center of rotation, and an outer ring 242 concentrically spaced from the rotary base 241, connected by multiple shielding sections 243, with slit sections 244 formed between each of the shielding sections 243. In other words, each of the shielding sections 243 functions as a plurality of shielding regions formed radially, and each of the slit sections 244 functions as a transmission region formed between the plurality of shielding sections 243. The structure of the rotary slit body rotation mechanism 25 is not particularly limited, and can be easily realized, for example, by transmitting the rotational force of a motor serving as a drive source to the rotary slit body 24 via a pulley and a connecting belt.

When acquiring an event signal ES using this third event generation means 2C, the first step involves placing the rotary slit body 24 of the third event generation means 2C between the event-based vision camera 1 and the imaging area PA, and the second step involves changing the positions of the shielding area and the transparent area of the rotary slit body 24 of the third event generation means 2C over time. In the first step, the rotary slit body 24 is positioned so that the shielding portion 243 and the slit portion 244 are simultaneously captured by the event-based vision camera 1. In the second step, the rotary slit body 24 is rotated in a fixed direction (e.g., clockwise CW in Figure 8) by the rotary slit body rotation mechanism 25, changing the positions of the shielding area and the transparent area over time. The fixed-direction rotation of the rotary slit body 24 causes brightness changes associated with the changes in the positions of the shielding area and the transparent area, allowing the event signal ES to be acquired by the event-based vision camera 1, whose imaging area PA is a stationary subject 3 or an unchanging surrounding environment. Therefore, it is possible to check the status of the photographing area PA, including the stationary subject 3 and the unchanging surrounding environment, and it is also possible to adjust the focus of the optical system 1b of the event-based vision camera 1.

Figure 10 shows the transition state of the imaging area PA visualized based on the event signal ES acquired from the event-based vision camera 1 when the rotary slit body 24 is operated by the rotary slit body rotation mechanism 25. Even when the rotary slit body 24 is operated by the rotary slit body rotation mechanism 25, the subject 3 in the imaging area PA is accurately captured. Note that the event signal ES cannot be acquired from pixels capturing areas where the positions of the shielding portion 243 (a shielded area) and the slit portion 244 (a transparent area) do not change over time. In other words, the positions of the rotating base 241 and the areas outside the outer ring portion 242 only function as shielded areas and do not change to transparent areas. Therefore, events cannot be generated and these areas cannot be visualized. Therefore, it is desirable to adjust the size of the rotary slit body 24 itself and its placement distance from the front of the event-based vision camera 1. Note that, because the interior of the imaging box 4 described above is relatively dark, if the rotary slit body 24 is made a light color (e.g., white), the event-based vision sensor 1a can detect a clear change in brightness. In addition, the width of the shielding portion 243 and the width of the slit portion 244 in the rotating slit body 24, the number of shielding portions 243 and slit portions 244 arranged, and the rotation speed have optimal values depending on the distance to the subject to be photographed, the size of the subject to be photographed, the surrounding lighting conditions, etc.

The first to third event generation means 2A to 2C described above generate events by changing the positions of the shielded and transparent areas through movement, but this is not the only method. Figure 11 shows a fourth event generation means 2D, which is composed of a liquid crystal shutter 26 and an applied voltage control mechanism 27 that controls the voltage applied to the liquid crystal shutter 26.

The liquid crystal shutter 26 in the fourth event generation means 2D holds the liquid crystal panel 262 in a bezel portion 261, and can be switched between a transparent state that transmits light and a blocking state that blocks light by adjusting the voltage applied to each liquid crystal cell that makes up the liquid crystal panel 262. That is, when the liquid crystal panel 262 is in the blocking state, the shutter surface of the liquid crystal panel 262 is reflected by the event-based vision camera 1, and when the liquid crystal panel 262 is in the transparent state, the shooting area PA is reflected by the event-based vision camera 1 through the liquid crystal panel 262. In addition, the applied voltage control mechanism 27 is connected to the liquid crystal shutter 26 via a cable 271, and controls the applied voltage so that the liquid crystal shutter 26 repeatedly switches between the transparent and blocking states at regular intervals, for example, by turning on the operation switch 272.

When acquiring an event signal ES using this fourth event generating means 2D, the first step is to place the liquid crystal shutter 26 of the fourth event generating means 2D between the event-based vision camera 1 and the shooting area PA, and the second step is to change the positions of the shielded area and the transparent area over time by controlling the applied voltage control mechanism 27 for the liquid crystal shutter 26 in the fourth event generating means 2D. In the first step, the liquid crystal shutter 26 is positioned so that the shutter surface of the liquid crystal panel 262 blocks the shooting direction of the event-based vision camera 1. In the second step, the shutter surface of the liquid crystal panel 262 is set to a blocking state, thereby alternating between a state in which the shielded area is positioned to block the shooting direction of the event-based vision camera 1 and a state in which the shutter surface of the liquid crystal panel 262 is set to a transparent state, thereby changing the positions of the shielded area and the transparent area over time. The periodic state change of the liquid crystal shutter 26 causes a change in brightness in accordance with the change in the position of the shielded area and the position of the transparent area, so that an event signal ES can be acquired by the event-based vision camera 1, which has an image capture area PA that is an unmoving subject 3 and an unchanging surrounding environment. Therefore, the status of the image capture area PA, which is an unmoving subject 3 and an unchanging surrounding environment, can be confirmed, and the focus of the optical system 1b of the event-based vision camera 1 can also be adjusted.

Figure 12 shows the transitional states of the imaging area PA visualized based on the event signal ES acquired from the event-based vision camera 1, when the liquid crystal shutter 26 is periodically changed in state under the control of the applied voltage control mechanism 27. Even when the liquid crystal shutter 26 is periodically changed in state under the control of the applied voltage control mechanism 27, the subject 3 in the imaging area PA is accurately captured. Furthermore, since the liquid crystal panel 262 of the liquid crystal shutter 26 is positioned to completely block the field of view of the event-based vision camera 1, when the liquid crystal shutter 26 is changed from the blocking state to the transparent state, an event occurs across the entire surface, and event signals ES can be acquired from all pixels of the event-based vision sensor 1a. This has the advantage of making it easier to obtain a clear image of the entire imaging area PA, including the subject 3 and its surrounding environment. The optimal value for the cycle between the transparent and blocking states depends on factors such as the distance to the subject, the size of the subject, and the ambient lighting conditions.

In addition to the first to fourth event generation means 2A to 2D described above, there are also other methods for acquiring an event signal ES from the event-based vision camera 1, such as the following.

A device that generates minute vibrations is attached to the event-based vision camera 1. For example, a small vibration device like those used in smartphones is attached to the body of the event-based vision camera 1 in an appropriate location, causing the body of the event-based vision camera 1 to vibrate. The vibration of the body of the event-based vision camera 1 simulates a change in the subject 3 and surrounding environment within the shooting area PA, allowing an event signal ES to be acquired. Note that the vibration period of the vibration device has an optimal value depending on the distance to the subject, the size of the subject, etc.

A flickering light is projected toward the lens of the event-based vision camera 1. For example, if flickering light is projected obliquely onto the lens of the event-based vision camera 1, a change in brightness occurs between when the subject 3 and the surrounding environment within the shooting area PA are visible and when the light is being projected, allowing an event signal ES to be acquired. The optimal value for the flickering period depends on factors such as the distance to the subject, the size of the subject, and the surrounding lighting conditions.

A flickering light is irradiated onto the subject. For example, if flickering light is irradiated onto the subject from an angle, a change in brightness occurs between when no light is irradiating the subject 3 or the surrounding environment within the shooting area PA and when light is irradiating the subject 3 or the surrounding environment within the shooting area PA, and therefore an event signal ES can be acquired. The optimal value for the flickering period depends on factors such as the distance to the subject, the size of the subject, and the surrounding lighting conditions.

The above describes an embodiment of the signal acquisition method for an event-based vision camera according to the present invention based on the attached drawings. However, the present invention is not limited to these embodiments, and may be implemented by adapting publicly known, existing equivalent technical means as long as the configuration described in the claims is not changed.

REFERENCE SIGNS LIST 1 Event-based vision camera 1a Event-based vision sensor 1b Optical system 2A First event generating means 21 Slit body 22 Slit body driving mechanism 3 Subject 4 Photography box 5 Signal cable 6 Information processing device PA Photography area CD Cross direction ES Event signal

Claims (1)

An event signal acquisition method for an event-based vision camera equipped with an event-based vision sensor that asynchronously outputs an event signal from a pixel that detects a change in brightness caused by movement of a subject in a shooting area or a change in the surrounding environment, the method receiving incident light from the subject that is not moving in the shooting area or the surrounding environment that is not changing and acquiring the event signal, comprising:
a first step of disposing an event generating means between the event-based vision camera and the photographing area where the event-based vision camera receives incident light;
a second step of changing, over time, a position of a shielding area that blocks incident light from the photographing area and a position of a transmission area that transmits incident light from the photographing area by the event generating means;
to cause a change in luminance in accordance with a change in the position of the shielding region and/or a change in the position of the transmitting region, and to acquire the event signal;
the event generating means includes a slit body in which the transmission area is formed as a slit portion between each of the shielding materials by arranging a plurality of shielding materials at intervals to function as the shielding area, and
performing the first step of arranging the slit body so that the shielding material and the slit portion are simultaneously captured by the event-based vision camera;
the second step of changing the positions of the blocking area and the transmitting area over time by moving the slit body in an intersecting direction that intersects with the shooting direction of the event-based vision camera so as to block the shooting direction of the event-based vision camera;
The event signal acquisition method for an event-based vision camera, wherein the event generating means supports the slit body via a swingable support that can swing the slit body in the intersecting direction.