JP2010170449A - Device and method for creating range image data for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device and method for creating range image data for a vehicle to continuously track the situation in front of one's own vehicle. <P>SOLUTION: The device includes a floodlight 5, an image intensifier 7b, a high-speed camera 8, a timing controller 9, and an image processing unit 10. The timing controller 9 controls so as to pick up an image with changing the amount of light in largeness at the same target distance. The image processing unit 10 processes steps S2-S6 to replace the luminance value of a pixel in the picked up image whose amount of light is reduced to the doubled value when the luminance value of the pixel in the picked up image whose amount of light is increased is saturated. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention belongs to the technical field of vehicle distance image data generation apparatus and method.

  In Patent Literature 1, whether or not an object such as an obstacle exists at the target distance is based on an image that is projected in accordance with the timing of reflected light that is projected in front of the host vehicle and returned from the target distance. Techniques for detection are disclosed.

US Pat. No. 6,732,123

  However, in the above prior art, objects other than the target distance cannot be detected. That is, there is a problem that the situation is intermittently grasped and the situation ahead of the host vehicle cannot be grasped continuously.

  An object of the present invention is to provide a vehicle distance image data generation apparatus and method that can continuously grasp the situation ahead of the host vehicle.

  In order to achieve the above object, in the present invention, light projecting means for projecting pulsed light in front of the host vehicle at a predetermined cycle, and reflected light returning from the target distance at an imaging timing set according to the target distance are provided. Based on the brightness of the same pixel in a plurality of captured images with different target distances obtained by the imaging means, an imaging means for imaging, a timing control means for controlling the imaging timing so that the target distance changes continuously Distance image data generation means for generating distance image data representing the distance to the object for each pixel, and the timing control means performs imaging with the same target distance and with the light projection amount varied. The distance image data generation means controls the light projection amount when the luminance value of the pixel in the image captured by increasing the light projection amount is saturated. With a correction means for replacing the value obtained by doubling the luminance values of pixels in the image captured by the fence, characterized in that.

  Therefore, in this invention, the situation ahead of the own vehicle can be grasped | ascertained continuously.

It is a block diagram which shows the structure of the obstruction detection apparatus 1 of Example 1. FIG. It is a figure which shows the temporal relationship between the operation | movement (light projection operation | movement) of the light projector 5, and the operation | movement (camera gate operation | movement) of the gate 7a at the time of imaging one imaging area. It is a figure which shows the state which a part of imaging area overlaps. It is a schematic diagram which shows a temporal luminance change at the time of imaging by increasing an imaging area infinitely. 3 is a flowchart illustrating a flow of distance image data generation control processing executed by the image processing unit 10 according to the first embodiment. It is a figure which shows the condition where four pedestrians AD exist in the different position ahead of the own vehicle. It is a schematic diagram which shows the temporal luminance change of the pixel corresponding to each pedestrian A-B. It is a figure which shows the distance image data generation effect | action of Example 1. FIG. It is explanatory drawing which shows the state of the saturation process of the luminance value of the distance image data generation apparatus of Example 1. FIG. 6 is a time chart of a state of multiple exposure in Example 2. It is a figure which shows the distance image data production | generation effect | action by the multiple exposure of Example 2. FIG. 12 is a time chart of a state of multiple exposure in Example 3.

  Embodiments for realizing the vehicle distance image data generating apparatus and method according to the present invention are described in the first embodiment corresponding to the first, second, and fifth aspects, and the first, second, third, and fifth aspects. A second embodiment corresponding to the present invention and a third embodiment corresponding to the first, second, third, fourth, and fifth aspects of the invention will be described.

First, the configuration will be described.
FIG. 1 is a block diagram illustrating a configuration of an obstacle detection apparatus 1 according to a first embodiment to which the vehicle distance image data generation apparatus according to the present invention is applied. A device 2, an object recognition processing unit 3, and a determination unit 4 are provided.

  The distance image data generation device 2 includes a projector (projecting unit) 5, an objective lens 6, a light doubling unit 7, a high-speed camera (imaging unit) 8, a timing controller (timing control unit) 9, and image processing. Unit (distance image data generating means) 10.

The projector 5 is a near-infrared LED 5a (which constitutes a lens and a light emitting unit) disposed at the front end of the vehicle, and according to a pulse signal output from the timing controller 9, a predetermined projection time tL (for example, 5 ns). During this period, pulse light is output. The cycle of the pulse signal is the projection cycle tP of the projector 5, and the projection cycle tP is, for example, an interval of 1/100 s or less.
The objective lens 6 is for receiving reflected light from an object, and is disposed adjacent to the projector 5. For example, the optical system is set to have an angle of view capable of capturing a predetermined range in front of the host vehicle.

The light multiplication unit 7 includes a gate 7a and an image intensifier 7b.
The gate 7a opens and closes in response to an opening / closing command signal from the timing controller 9. Here, in Example 1, the opening time (gate time) tG of the gate 7a is set to 5 ns, which is the same as the light projection time tL. Here, the gate time tG corresponds to the imaging target width of the imaging area (target distance). The longer the gate time tG, the longer the imaging target width of the imaging area. In the first embodiment, since the gate time tG = 5 ns, the imaging target width is 1.5 m from the speed of light (about 3 × 10 ⁸ m / s) × gate time (5 ns).

  The image intensifier 7b temporarily converts extremely weak light (reflected light from an object, etc.) into electrons and then electrically amplifies it, and returns it to a fluorescent image again, thereby doubling the amount of light and producing an image with contrast. It is a viewing device. Photoelectrons launched from the photocathode of the image intensifier 7b by a photoelectric phenomenon are accelerated by a high voltage of the order of kV, and are emitted to the phosphor screen on the anode side, thereby emitting fluorescence having a photon number of 100 times or more.

The fluorescence generated on the phosphor screen is guided to the image sensor of the high-speed camera 8 by the fiber optic plate without being scattered while maintaining the same positional relationship.
The high-speed camera 8 captures an image emitted from the light doubling unit 7 in response to a command signal from the timing controller 9 and outputs a captured image (color image) to the image processing unit 10. In the first embodiment, a camera having a resolution of 640 × 480 (horizontal: vertical), a luminance value of 1 to 255 (256 levels), and 100 fps or more is used.

The timing controller 9 is the time from the light projection start time of the projector 5 until the gate 7a is opened so that the captured image captured by the high-speed camera 8 is the timing of the reflected light returning from the target imaging area. The imaging timing is controlled by setting a certain delay time tD and outputting an open / close command signal corresponding to the delay time. That is, the delay time tD is a value that determines the distance from the host vehicle to the imaging area (imaging target distance), and the relationship between the delay time tD and the imaging target distance is as follows.
Imaging distance = speed of light (approx. 3 x 10 ⁸ m / s) x delay time tD / 2
FIG. 2 shows a temporal relationship between the operation of the projector 5 (light projection operation) and the operation of the gate 7a (camera gate operation) when imaging one imaging area.

  The timing controller 9 increases the imaging range of the high-speed camera 8 by increasing the delay time tD by a predetermined interval (for example, 10 ns) so that the imaging area continuously moves from the front side of the vehicle to the front side. Change to the side. The timing controller 9 starts the imaging operation of the high-speed camera 8 immediately before the gate 7a is opened, and ends the imaging operation after the gate 7a is completely closed. However, in the first embodiment, the timing controller 9 sets the number of multiple exposures in advance according to the imaging target distance (target distance), reads this data, and performs imaging at a certain imaging target distance a predetermined number of times. And the opening / closing operation of the gate 7a. Therefore, when the predetermined number of times set is a plurality of times, the imaging operation is terminated after a plurality of light projection operations and the opening / closing operation of the gate 7a.

  Further, in the first embodiment, as illustrated in FIG. 3, when the imaging target distance is continuously changed from B1 → B2 → B3 →..., The imaging target distance is increased more than the imaging target width A of the imaging area. By increasing the amount (B2-B1), the increase amount of the imaging target distance is set so that a part of the imaging area changes while overlapping.

  FIG. 4 is a schematic diagram showing temporal luminance changes when the amount of increase in the imaging target distance is reduced to the limit, in other words, when imaging is performed with an infinite increase in the imaging area. By overlapping each other, the luminance value of the same pixel in a plurality of consecutive captured images gradually increases, and after the peak, the luminance value gradually decreases. In practice, the number of imaging areas is limited (1 to n), but by overlapping a part of continuous imaging areas, the temporal luminance change becomes close to the characteristics of FIG.

The timing controller 9 outputs an image processing command signal to the image processing unit 10 when all the captured images for one frame, that is, the set predetermined range (area 1, area 2,..., Area n) are captured. To do.
In the first embodiment, the timing controller 9 performs imaging of each imaging area described above, that is, imaging for one frame with a predetermined first light projection amount and a light projection amount that is ½ of the first light projection amount. Imaging is performed even with the second light projection amount.

  The image processing unit 10 generates distance image data representing distance information by color, luminance, and the like from one frame of captured images (imaging pixels) captured by the high-speed camera 8, and object recognition is performed on the generated distance image data. Output to the processing unit 3.

The object recognition processing unit 3 identifies an object included in the distance image data by performing image processing, for example, labeling, pattern matching, or the like on the object included in the distance image data.
Based on the relationship (distance, relative speed, etc.) between the object (person, car, sign, etc.) identified by the object recognition processing unit 3 and the host vehicle, the determination unit 4 presents information to the driver by an alarm, Determine whether vehicle control such as automatic braking is necessary.

[Distance image data generation control processing]
FIG. 5 is a flowchart illustrating the flow of the distance image data generation control process executed by the image processing unit 10 according to the first embodiment. Each step will be described below. This process is repeatedly executed at a predetermined calculation cycle.

  In step S1, the image processing unit 10 stores the luminance value data having the lowest luminance of the captured image obtained by imaging the front of the host vehicle without performing the light projection by the projector 5 for later luminance determination, and proceeds to step S2. To do. This data is used when generating the distance image data.

  In step S2, the image processing unit 10 inputs captured images of the first light projection amount and the second light projection amount, and proceeds to step S3.

  In step S3, the image processing unit 10 determines whether or not the luminance value of each pixel in the image picked up with the first light projection amount is saturated. If it is saturated, the process proceeds to step S4, and is not saturated. If so, go to step S5. Note that the saturation of the luminance value is determined based on whether or not a predetermined luminance threshold is reached.

  In step S4, the image processing unit 10 replaces the saturated luminance value of the pixel imaged with the first light projection amount with a value obtained by doubling the luminance value of the second light projection amount, and updates it as processing data used for the distance image. To do.

  In step S5, the image processing unit 10 updates the luminance value of the pixel imaged with the first light projection amount as processing data used for the distance image.

  In step S6, the image processing unit 10 determines whether or not the saturation processing for one image corresponding to one imaging area is completed. If completed, the process proceeds to step S7. If not completed, the process proceeds to step S3. Return. By repeating this flow of steps S6 → S3, saturation processing of each pixel is performed.

  In step S7, the image processing unit 10 determines whether or not image input for one frame (area 1, area 2,..., Area n) has been completed. If YES, the process proceeds to step S8, and if NO, the process returns to step S2.

  In step S8, distance image data is generated as an image with distance information by color and brightness, and the process proceeds to return.

Next, the operation will be described.
[Distance image data generation function]
The timing controller 9 controls the imaging timing of the high-speed camera 8 by setting the delay time tD so that the captured image captured by the high-speed camera 8 becomes the timing of the reflected light returning from the target imaging area. To do. When an object is present in the target imaging area, the time for the light emitted from the projector 5 to return from the imaging area is the time for the light to reciprocate the distance between the host vehicle and the imaging area (imaging target distance). Therefore, the delay time tD can be obtained from the imaging target distance and the speed of light.

  In the captured image of the high-speed camera 8 obtained by the above method, when an object exists in the imaging area, the luminance value data of the pixel corresponding to the position of the object is affected by the reflected light, and the luminance of other pixels Indicates a value higher than the value data. Thereby, based on the luminance value data of each pixel, the distance from the object existing in the targeted imaging area can be obtained.

  Furthermore, in the first embodiment, captured images of the imaging areas 1 to n are acquired while changing the delay time tD. Subsequently, the brightness value data of the distance before and after the same pixel position is compared, the highest brightness value data is set as the distance of the object detected by the pixel, and the data (distance with distance information of the imaging range (640 × 480)) Image data).

  Conventional distance detection methods using laser radars and stereo cameras are susceptible to rain, fog, snow, etc., and the noise level with respect to the signal level is large (the SN ratio is small), so the reliability in bad weather is low. . When using a millimeter wave radar that is not easily affected by bad weather, the reliability of distance detection is high, but it is difficult to perform object recognition (object identification) from the millimeter wave radar signal. Is required. Further, since the camera image becomes unclear during bad weather, it is difficult to perform accurate object recognition.

On the other hand, in the first embodiment, only reflected waves returning from the target imaging area are reflected in the captured image, so that the light bent due to the influence of rain, fog, snow, or the like, that is, the noise mixing level is kept low. High signal-to-noise ratio can be obtained. That is, high distance detection accuracy can be obtained regardless of bad weather or night.
And since the distance of the object detected from an image is known from the produced | generated distance image data, when performing object recognition using methods, such as pattern matching after that, the distance with an object can be grasped | ascertained instantaneously.

  Furthermore, in the first embodiment, the captured area is continuously changed to acquire a plurality of captured images, and the captured images are compared to detect the distance of each pixel. In addition, it can be grasped over a wide range. For example, even in a situation where a pedestrian has jumped between the host vehicle and the preceding vehicle, the distance between the preceding vehicle and the pedestrian can be grasped at the same time. Control can be performed.

FIG. 6 shows a situation in which four pedestrians A to D exist at different positions in front of the host vehicle, and the relationship between the distance between the host vehicle and each pedestrian is A <B <C <D. .
At this time, in the first embodiment, a part of the imaging area is overlapped so that the reflected light from one object is reflected on the pixels constituting the object of the captured image in the plurality of imaging areas in which the reflected light is continuous. For this reason, the temporal luminance change of the pixels constituting the object corresponding to each pedestrian shows a triangular characteristic that takes a peak at the position of the pedestrian as shown in FIG.

  Since the distance image data is data used for alarms and vehicle control, it is impossible to set an imaging area infinitely finely as long as a certain calculation speed is required. By making the reflected light from the plurality of captured images included, as shown in FIG. 8, the temporal luminance change of the pixel is approximated to the above characteristics, and the imaging area corresponding to the peak of the triangular portion is By setting the distance of the object in the pixel, detection accuracy can be increased.

[Saturation action]
FIG. 9 is an explanatory diagram illustrating a state of saturation processing of luminance values of the distance image data generation device according to the first embodiment.
In FIG. 9, the horizontal axis indicates the distance, and the luminance value of the same pixel is shown in a plurality of images with different imaging areas.
In imaging for obstacle detection, if imaging is performed with an object that has a relatively low reflectance for reliable detection, it will be before and after an extremely high reflectance such as a vehicle reflector or a road sign. Therefore, the luminance value picked up from becomes saturated, and the accurate distance becomes difficult. That is, as shown by the luminance characteristic 102 in FIG. 9A, when the luminance value is saturated, the target distance that becomes the peak luminance cannot be measured accurately. In other words, it is impossible to determine which of the saturation ranges has a peak.

In the first embodiment, the saturation process is performed so that the target distance of the peak luminance can be detected even when imaging is performed in accordance with an object having a low reflectance.
In the first embodiment, imaging with a first light projection amount set in accordance with an object having a low reflectance (see FIG. 9A) and imaging with a light projection amount ½ of the first light projection amount (FIG. 9 ( b)).
Then, in imaging with the first light projection amount, as shown in the luminance characteristic 101 in FIG. 9A, an object having a low reflectance can obtain a luminance peak, but as shown in the luminance characteristic 102 in FIG. 9A. An object with high reflectivity has a saturated luminance peak.

On the other hand, in the imaging of the second light projection amount, since the light projection amount is halved, as shown by the luminance characteristics 103 and 104 in FIG. However, a luminance peak can be reliably obtained even for an object having a high reflectance.
Then, by the processing in steps S2 to S6, the brightness value saturated with the pixels of the image captured with the first light projection amount is detected and replaced with a value obtained by doubling the luminance value of the second light projection amount. The processing data for creating is as shown in FIG.

In FIG. 9C, what is not saturated in the luminance characteristic 101 of FIG. 9A becomes processing data used for generating the distance image data as it is. For the saturated one, all the luminance data in the saturation range can be replaced with a value obtained by doubling the value captured with the second light projection amount, as shown by the luminance characteristic 105 in FIG. Together with the luminance characteristic 102, the luminance characteristic can be detected.
This improves the accuracy of the distance image generated using the processing data. Then, the obstacle is reliably detected by imaging the object with the light projection amount adjusted to an object having a low reflectance.

  Next, the effect will be described.

  In the vehicle distance image data generation apparatus and method according to the first embodiment, the effects listed below can be obtained.

  (1) A projector 5 that projects pulsed light in front of the host vehicle at a predetermined period, an image intensifier 7b that captures reflected light returning from the target distance at an imaging timing set according to the target distance, and a high speed The same pixel in a plurality of captured images with different target distances obtained by the camera 8, the timing controller 9 that controls the imaging timing so that the target distance changes continuously, the image intensifier 7b, and the high-speed camera 8 An image processing unit 10 that generates distance image data representing a distance to an object for each pixel based on luminance is provided, and the timing controller 9 performs control so as to perform imaging while changing the amount of light emitted from the same target distance. Then, the image processing unit 10 increases the luminance value of the pixels in the image captured by increasing the light projection amount. , Because with the processing of step S2~S6 replaced with the value obtained by doubling the luminance values of pixels in the image captured by reducing the projection amount, the condition of the vehicle ahead can be continuously grasp. In addition, it is possible to improve the detection accuracy of distance image data by reliably detecting a luminance peak while reliably detecting an obstacle with a large amount of light projection.

  (2) In the above (1), the timing controller 9 captures an image at the same target distance by using a first light emission amount having a large light emission amount and a second light emission amount that is ½ of the first light emission amount. The processes of steps S2 to S6 of the image processing unit 10 are controlled so that the luminance value of the pixel in the image captured with the second light projection amount is saturated when the luminance value of the pixel in the image captured with the first light projection amount is saturated. Is replaced with a value obtained by doubling the luminance value obtained by imaging the saturated luminance value with the second light emission amount while reliably detecting an obstacle with the first light emission amount which is a large light emission amount. By replacing, it is possible to reliably detect the luminance peak and improve the detection accuracy of the distance image data.

  (5) Pulse light is projected by the projector 5 at a predetermined period in front of the host vehicle, and reflected light returning from the target distance at the imaging timing set according to the target distance is reflected to the image intensifier 7b and the high-speed camera 8 In the same target distance, imaging is performed by changing the light projection amount in large and small, and the timing is controlled by the timing controller 9 so that the target distance continuously changes, and the light projection amount is increased. When the luminance value of the pixel in the captured image is saturated, the image processing unit 10 performs correction by the processing in steps S2 to S6 in which the light emission amount is reduced and the luminance value of the pixel in the captured image is replaced with a doubled value. A distance image representing the distance to the object for each pixel based on the brightness of the same pixel in a plurality of captured images with different target distances obtained by correction Since the data is generated by the image processing unit 10, the situation ahead of the host vehicle can be grasped continuously. Further, it is possible to improve the detection accuracy of the distance image data by reliably detecting the luminance peak while reliably detecting an obstacle with a large amount of light projection.

The second embodiment is an example of a distance image data generation apparatus that performs multiple exposure.
The configuration will be described.
The timing controller 9 according to the second embodiment sets the number of multiple exposures in advance according to the imaging target distance, reads this data, and performs a predetermined number of times of light projection operation and gate 7a at one imaging target distance. It is made up of opening and closing operations. Therefore, the imaging operation is terminated after a plurality of light projection operations and the gate 7a opening / closing operation.
Since other configurations are the same as those of the first embodiment, description thereof is omitted.

The operation will be described.
[Brightness correction by multiple exposure]
FIG. 10 is a time chart of the multiple exposure state in the second embodiment. FIG. 11 is a diagram illustrating a distance image data generation operation by multiple exposure according to the second embodiment.
10A shows a pulse indicating the light projection timing, FIG. 10B shows a pulse indicating the shutter timing, and FIG. 10C shows a state of accumulation, reset, and the like of the image reception amount of the high-speed camera 8.
In the distance image data generation device 2 according to the second embodiment, a plurality of captured images are acquired while gradually increasing the imaging target distance, and thus reflected light from an object existing in a far imaging area It becomes weaker than the reflected light of the object existing in the. For this reason, when the imaging time (gate time tG) is constant in each imaging area, the captured image becomes darker as the imaging area is farther.

  On the other hand, the image processing unit 10 generates the distance image data representing the distance to the object for each pixel based on the luminance of the same pixel in the plurality of captured images. If a luminance difference due to a difference occurs, an accurate comparison cannot be performed when comparing the luminance of the same pixel.

In contrast, in the second embodiment, the number of multiple exposures is set and stored with respect to the imaging target distance so that the luminance peak value (maximum luminance value) of the captured image in the imaging area where the object exists is the target luminance. . Then, the timing controller 9 performs a plurality of sets of a light projecting operation and an opening / closing operation of the gate 7a on one image according to the set number of multiple exposures. That is, the number of multiple exposures in the second embodiment refers to the light projecting operation of the projector 5 performed by the control of the timing controller 9 for one image captured by the high-speed camera 8, and the light projecting operation as described above. It means the number of repetitions of the opening / closing operation of the gate 7a (by the delay time tD).
Furthermore, in Example 2, in order to perform multiple exposure and to perform imaging with the first light projection amount and the second light projection amount, as shown in FIG. 11, after imaging with the first light projection amount with a large number of multiple exposures, After the image reading process is performed inside the high-speed camera 8, the accumulated received light amount is reset, and then the number of multiple exposures is halved of the first light projection amount (FIGS. 11A and 11B). In this case, the image is picked up with the second light projection amount that is ½ of the first light projection amount.
Note that an image captured by multiple exposure is one image. Therefore, in the second embodiment, in the same imaging area (same target distance), one image with the first light projection amount and one image with the second light projection amount are obtained, so the processing in the image processing unit 10 is performed in the same manner as in FIG. Is called.

  Thus, in the second embodiment, the luminance range width (difference between the minimum luminance value and the maximum luminance value) of each captured image with different imaging target distances is made uniform regardless of the imaging area, and is set in advance so that good processing can be performed. The target brightness can be approached (see FIG. 9).

Explain the effect. In the vehicle distance image data generation device according to the second embodiment, the following effects can be obtained in addition to the above (1), (2), and (5).
(3) In the above (1) or (2), the timing controller 9 captures a captured image of one target distance a plurality of times at a light projection by the projector 5 and a plurality of times at an imaging timing by the high-speed camera 8. Since the control is performed so that the brightness peak of an object located far away can be obtained close to the brightness peak of an object located nearby by multiple exposure, an object at a far distance can be detected reliably. Distance image data can be generated.
Since other functions and effects are the same as those of the first embodiment, description thereof is omitted.

The third embodiment is an example of a distance image data generation device that performs multiple exposure and considers the frame rate.
The configuration will be described.
In the timing controller 9 of the third embodiment, imaging for the number of times of multiple exposure is configured by a predetermined number of light projection operations and an opening / closing operation of the gate 7a so as to perform multiple exposure. Further, in the timing controller 9 according to the third embodiment, the imaging stop for a predetermined time at the timing when the light projection amount becomes 1/2 of the whole in the predetermined number of light projection operations set by the number of multiple exposures and the gate 7a opening / closing operation. After that, control is performed so that the remaining half of the imaging operation is performed.

In the third embodiment, the high-speed camera 8 outputs an image captured at that time in a period in which the imaging operation is stopped in a state in which the light projection amount is ½ of the total amount, and the accumulated image receiving amount Without resetting, the remaining half of the imaging operation is performed, and the entire captured image is output.
Since other configurations are the same as those of the second embodiment, description thereof is omitted.

The operation will be described.
[Brightness correction by multiple exposure]
FIG. 12 is a time chart of the multiple exposure state in the third embodiment.
12A shows a pulse indicating the light projection timing, FIG. 12B shows a pulse indicating the shutter timing, and FIG. 12C shows a state in which the image receiving amount of the high-speed camera 8 is accumulated and reset.
In the distance image data generation device 2 according to the third embodiment, when the timing controller 9 performs a plurality of sets of the light projecting operation and the opening / closing operation of the gate 7a according to the set number of multiple exposures, the following is performed. Output the captured image. When the light projection amount is halved, that is, when the number of times of light projection in the multiple exposure reaches half of the total number, the imaging operation is temporarily stopped. Then, the captured image at this time is output to the inside or outside of the high-speed camera 8. In the third embodiment, this is imaging with the second light projection amount.

After that, the timing controller 9 performs the remaining half of the imaging operation. At this time, the high-speed camera 8 further accumulates the accumulated image reception amount without resetting it. Then, after the imaging operation for a predetermined number of times of multiple exposure, the high-speed camera 8 outputs a captured image. This is imaging with the first light projection amount.
As described above, in the third embodiment, since the first light projection amount and the second light projection amount are captured in one time, the imaging time can be saved and the frame rate can be improved.

Here, the frame rate in the distance image data generation device 2 according to the third embodiment indicates the number of captured images when one distance image is generated, and this number is the number of imaging areas. If this is affected, the accuracy of the distance image will be affected.
In the third embodiment, a doubled value of a value with a small amount of light projection is used in a portion where the luminance value is saturated while performing reliable detection with a large amount of light projection by imaging with a first light projection amount and imaging with a second light projection amount. Thus, the luminance peak is reliably detected. Furthermore, the detection accuracy is improved by making the detection accuracy uniform between the near target distance and the far imaging target distance by multiple exposure. Further, at that time, image receiving data at the time when the number of exposures reaches half is read out by an imaging process by one multiple exposure, and two images having different exposure times are taken. As a result, it is possible to perform imaging with different light amounts without affecting the frame rate.

Explain the effect. In the vehicle distance image data generation device according to the third embodiment, in addition to the above (1), (2), (3), (5), the following effects can be obtained.
(4) In the above (3), the timing controller 9 projects a plurality of times of light projection by the projector 5 performed as an image of one target distance and a plurality of times of image capture at the image capturing timing of the high-speed camera 8. The high-speed camera 8 provides a stop period for light and imaging, and the high-speed camera 8 outputs to the image processing unit 10 a captured image that has been received until the stop period and a captured image that has been received in a plurality of times. With the imaging of the imaging target distance, it is possible to perform imaging with two light projection amounts, and it is possible to improve the accuracy of the distance image data with different light projection amounts without affecting the frame rate.

  As described above, the vehicle distance image data generation apparatus and method according to the present invention have been described based on the first to third embodiments, but the specific configuration is not limited to these embodiments, and Design changes and additions are permitted without departing from the spirit of the invention according to each claim of the scope.

  For example, in the embodiment, the number of light projections is two, but may be three or more. However, it is desirable that there is no influence on the frame rate.

  The present invention can be used for imaging for detecting the presence or absence of an object in an environment such as fog.

DESCRIPTION OF SYMBOLS 1 Obstacle detection apparatus 2 Distance image data generation apparatus 3 Object recognition process part 4 Judgment part 5 Projector 6 Objective lens 7 Light multiplication part 7a Gate 7b Image intensifier 8 High speed camera 9 Timing controller 10 Image processing part

Claims (5)

Light projecting means for projecting pulsed light in front of the host vehicle at a predetermined period;
Imaging means for imaging reflected light returning from the target distance at an imaging timing set according to the target distance;
Timing control means for controlling the imaging timing so that the target distance changes continuously;
Distance image data generation means for generating distance image data representing a distance to an object for each pixel based on the luminance of the same pixel in a plurality of captured images with different target distances obtained by the imaging means;
With
The timing control means includes
Control to perform imaging with the amount of emitted light changed in the same target distance,
The distance image data generation means includes
When the luminance value of the pixel in the image captured by increasing the light emission amount is saturated, the correction unit is provided to replace the luminance value of the pixel in the image captured by decreasing the light emission amount with a doubled value.
A vehicular distance image data generating apparatus characterized by the above. The vehicle distance image data generation device according to claim 1,
The timing control means includes
Control is performed so that imaging is performed at the same target distance by a first light emission amount with a large light emission amount and a second light emission amount that is a half of the first light emission amount,
The correction unit of the distance image data generation unit includes:
When the luminance value of the pixel in the image captured with the first light projection amount is saturated, the luminance value of the pixel in the image captured with the second light projection amount is replaced with a value that is doubled.
A vehicular distance image data generating apparatus characterized by the above. In the vehicular distance image data generating device according to claim 1 or 2,
The timing control means includes
Control is performed so that a captured image of one target distance is generated by a plurality of times of light projection by the light projecting unit and a plurality of times of imaging at the imaging timing by the image capturing unit.
A vehicular distance image data generating apparatus characterized by the above. In the vehicular distance image data generating device according to claim 3,
The timing control unit provides a light projection and imaging stop period in the middle of a plurality of times of light projection by the light projection unit performed as imaging of one target distance and a plurality of times of imaging at the imaging timing by the imaging unit, The imaging unit outputs the captured image for the image received by the stop period and the captured image for the entire plurality of imagings to the distance image data generation unit,
A vehicular distance image data generating apparatus characterized by the above. Pulse light is emitted in front of the vehicle at a predetermined cycle,
Capture reflected light returning from the target distance at the imaging timing set according to the target distance,
At the same target distance, do the imaging with the amount of emitted light changed to large or small,
Controlling the imaging timing so that the target distance changes continuously;
When the luminance value of a pixel in an image captured with a large amount of emitted light is saturated, the luminance value of a pixel in the image captured with a small amount of emitted light is corrected and replaced with a doubled value.
Based on the luminance of the same pixel in a plurality of captured images with different target distances obtained by the correction, the distance image data representing the distance to the object for each pixel is generated,
A vehicle distance image data generation method characterized by the above.