JP2017191082A - Bright-spot image acquisition apparatus and bright-spot image acquisition method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging apparatus capable of easily acquiring a bright-spot image of an entire measuring object even when there are portions with different reflectance ratios on a surface of a measuring object as a subject or strong light enters only a part of the surface of the measuring object.SOLUTION: A bright-spot image acquisition apparatus includes: a background light projector that projects uniform light to a measuring object at timing different from that of a bright-spot projector; and a controller for controlling the projection timings of the bright-spot projector and the background light projector. The bright-spot acquisition apparatus composes the bright-spot image and background image acquired and output by a camera and corrects differences in brightness of the bright-spot image caused by difference in reflectance ratios of the surface of the measuring object.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a technique for performing three-dimensional measurement of a target object.

  The present invention divides a light beam such as infrared rays into a plurality of light beams, projects the light onto the object to be measured, and acquires three-dimensional distance information related to the shape of the object to be measured from an image obtained by photographing a bright spot group reflected from the object to be measured. The present invention relates to a bright spot image acquisition device and a bright spot image acquisition method. As such an apparatus, there is a state analysis apparatus disclosed in Japanese Patent No. 3764949. (Patent Document 1)

  In this apparatus, infrared laser light is used as a light source, and pattern light, which is a plurality of bright spot arrays, is projected from the bright spot projector onto the object to be measured using a fiber grating. The light beam from such a bright spot projector is reflected by the object to be measured, and the image is captured by the camera. Three-dimensional distance information of the object to be measured is acquired using information on the bright spot of the image captured by the camera.

  However, if the surface of the object or the object to be measured is not uniform and partially different in the light rays to be projected, the bright spot image cannot be extracted well or the bright spot group is extracted. Processing may be complicated. This occurs when an image of a person wearing clothes in which fabrics with extremely different reflectances are distributed.

  The same problem arises when measuring an object to be measured in which natural light or external light is applied to only a part of the surface.

  In such a case, conventionally, in order to measure more accurately, a method of dividing an image into blocks and calculating a threshold value for each block has been used. (Patent Document 2). However, in this case, the calculation processing of the bright spot image becomes heavy, and it takes time for signal processing. As a result, it is difficult to perform the calculation processing in real time in applications such as monitoring an object. .

Japanese Patent No. 3764949 Japanese Patent No. 3465226

  An object of the present invention is to enable a bright spot imaging device to easily acquire an image of an entire object to be measured even if there is a portion having a different reflectance on the surface of the object to be measured that is a subject. A bright spot image acquiring apparatus and a bright spot image acquiring method capable of easily extracting individual bright spots even with objects to be measured having different reflectivities. Further, even when strong light is incident only on a part of the surface of the object to be measured, a bright spot image of the entire object to be measured can be acquired.

  The present invention provides a bright spot projector for projecting a bright spot pattern on an object to be measured, and a bright spot image that is arranged at a position away from the bright spot projector and reflected from the bright spot projected light from the object to be measured. In a camera that acquires and outputs and an apparatus that obtains three-dimensional distance information by processing an output signal of the camera, and further projects uniform light onto the object to be measured at a timing different from that of the bright spot projector. A background light projector and a controller for controlling the light projection timing of the two projectors are provided, and a bright spot image acquired and output by the camera and a background image are synthesized, and the reflectance of the surface of the object to be measured This is a bright spot image acquisition device having an image processing unit that corrects a brightness difference of a bright spot image due to a difference in brightness.

  The present invention obtains a background image acquired from a camera that shoots the object to be measured at the time of background light projection, which projects uniform light on the object to be measured, and a camera when a bright spot pattern is projected on the object to be measured. A correction coefficient map image using the reciprocal of the luminance of the background image is created using the bright spot image, and the luminance of the bright spot image is corrected by multiplying the correction coefficient of the correction coefficient map image by the previous bright spot image. A bright spot image acquisition method is adopted.

  The present invention provides a bright spot image acquiring apparatus and a bright spot image acquisition device that can easily extract the entire bright spot group even if the target is different in reflectance by adding a projector that uniformly illuminates the entire target object. This is a point image acquisition method.

  In another modification of the present invention, the background image signal acquired from the camera at the time of background light projection and the bright spot image signal acquired from the camera when the bright spot is projected are used. A subtractor that subtracts the brightness of the bright spot image by synthesizing the output of one subtractor, the low-pass component through the low-pass filter, and the output of the other subtractor. It is a point image acquisition device.

  The present invention includes a projector control unit that projects the bright spot projector and the background light projector at different timings, and the bright spot image projected with the bright spot and the background image projected with the background light are captured by the camera. It is the bright spot image acquisition apparatus acquired from (1).

  According to the present invention, even when the surface of the object to be measured has a partially different reflectance, a three-dimensional shape obtained by accurately extracting a bright spot image and calculating the bright spot image. Can be acquired in a shorter calculation time.

FIG. 2 is a block diagram showing a configuration of a first exemplary embodiment of the present invention. FIG. 3 is a plan view showing the arrangement of objects to be measured. FIG. 3 is a timing waveform chart showing an example of a control signal of the first embodiment. FIG. 3 is a block diagram illustrating in more detail the inside of the bright spot image luminance correction means 10 of the first embodiment. These are block diagrams which show the structure of the additional part of a 2nd Example. These are explanatory drawings showing signal waveforms of respective parts of the configuration of the second embodiment.

  Hereinafter, an embodiment of an embodiment according to the present invention will be described with reference to the drawings. The embodiment will be described by arranging hardware so that the operation can be easily described. However, the control unit and the like can be similarly implemented by computer software processing.

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.
In the bright spot image acquisition device of the present invention, as shown in FIG. 1, the bright spot projector 2 that projects an infrared bright spot 31 onto the object 13 and the bright spot projector drive circuit 1 that drives the bright spot projector 2 are provided. In addition, a separate background light projector 4 that projects a uniform infrared ray 32 different from the pattern light and a background light projector drive circuit 3 that drives the background light projector 4 are separately provided on the same object to be measured 13. The light source may be an infrared laser or an infrared LED.

  The bright spot projector driving circuit 1 and the background light projector driving circuit 3 are connected to a projector control section 6 in the image processing section 7, and are output by a bright spot projector control signal 14 and a background projector control signal 15 which are output signals of the projector control section 6. Be controlled. In this embodiment, the bright spot projector driving circuit 1, the background light projector driving circuit 3, and the projector control unit 6 are configured independently. However, the whole or a part of them may be combined into a control unit having a smaller number. Any device that can output each control signal is possible. The projector control unit also supplies control signals for controlling operation timings of a camera 5, a bright spot image receiving unit 8 and a background image receiving unit 9 which will be described later.

  The infrared rays 31 and the infrared rays 32 reflected by the object to be measured 13 are imaged by the camera 5. The video signal 16 that is the output of the camera 5 is introduced into the bright spot image receiving unit 8 and the background image receiving unit 9.

  The output signals of the bright spot image receiving unit 8 and the background image receiving unit 9 are taken into the bright spot image luminance correction means 10 and the luminance correction processing according to the present invention is executed. The output of the bright spot correcting means 10 is derived to the distance measuring means 11 and is processed by the distance image processing unit 12 to obtain three-dimensional distance information, as in the conventional example.

  First, luminance correction, which is a feature of the present invention, will be described. 2B to 2C, a fabric B102 having a reflectance different from that of the fabric A and a fabric C103 having a reflectance different from that of the fabric A and the fabric B are placed on the fabric A101. It shall be. FIG. 2 is a plan view showing the arrangement of the object to be measured.

2a shows an image 20 by reflected light when visible light is projected, and FIG. 2b shows an image 22 by reflected light when infrared light is projected. FIG. 2 c shows a bright spot image 21 that is the output of the camera 5.

  Here, as an example of the object to be measured, a fabric A indicated by 101, a fabric B indicated by 102, and a fabric C indicated by 103 are arranged for comparison. Due to the difference in reflectance depending on the projected light, different images are obtained when the object to be measured as shown in the image 20 and the image 22 is imaged by the camera. The influence of this difference in reflectance is similarly affected by the bright spot image of the camera when bright spot infrared rays are projected onto the same object to be measured. As described above, the difference in the image due to the difference in the reflectance of the fabric appears as a problem when trying to obtain posture and position information of the human body itself, or when measuring the respiratory waveform while measuring the human body while wearing the body. .

  Since the reflectance varies depending on the subject and the object to be measured, when trying to obtain a bright spot image of the entire screen, it may be partially bright and indistinguishable between bright spots, or it may be partially dark. As a result, there are inconveniences that it becomes impossible to distinguish the bright spots and that it takes time to acquire the bright spot information. There are cases where the thresholds for extracting the bright spots are different, the calculation time of the bright spot information increases, and the bright spots cannot be extracted well.

  FIG. 3 is a timing waveform diagram showing an example of a control signal output by the projector control unit 6. In FIG. 3a, 27 is a bright spot projection control signal, and in FIG. 3b, 26 is a background projection control signal. In FIG. 3 c, the outline of the background image 22 and the luminance image 21 that are outputs from the camera 5 at each timing is shown below the waveform signals 26 and 27.

  The bright spot projector 2 and the background light projector 4 project the object 13 to be measured at different timings (FIGS. 3A and 3B), and the bright spot image 21 and the background light image 22 are captured by the camera 5, respectively.

  Although it is desirable that the wavelength of the infrared ray 31 projected by the bright spot projector 2 and the wavelength of the infrared ray 32 projected by the background light projector 4 are the same wavelength, these wavelengths are somewhat different. For example, the wavelength of the bright spot projector 2 Even if the wavelength is 808 nm and the wavelength of the background light projector 4 is 810 nm or 850 nm, the present invention can be implemented with almost no problem.

  FIG. 4 is a block diagram showing in more detail the inside of the bright spot image luminance correction means 10 shown in FIG.

  A luminance image 21 that is an output signal of the luminance image receiving unit 8 is introduced into the normalizing means 19. A background image 22 that is an output signal of the background image receiving unit 9 is introduced into the correction coefficient calculation means 17.

  From the background image 22, the luminance of the position of each pixel of the output image of the camera 5 on the surface of the object to be measured that is the subject is obtained. The luminance when an object having a reflectance of 100% is unknown is unknown, but the luminance at each position is determined in proportion to the reflectance at that position.

  When the reflectance of the portion of the fabric A101 is 80%, the reflectance of the portion of the fabric B102 is 20%, and the reflectance of the portion of the fabric C103 is 40%, the camera 5 can obtain an 8-bit output. When the video output of the% subject is 255, an output value of 204 is obtained for the portion of the fabric A101, 61 for the portion of the fabric B102, and 102 for the portion of the fabric C103.

  When the shutter speed of the camera 5 and the irradiation intensity of the background light are changed and the output of a subject with 100% reflectance is 100, the fabric A101 portion is 80, the fabric B102 portion is 20, and the fabric C103 portion is 40. Output.

  In any case, the output of the portion of the fabric C103 is half of the portion of the fabric A101, and the output of the portion of the fabric B102 is 1/4 of the output of the portion of the fabric A101.

  The correction coefficient calculation means 17 can obtain “255 / output of each fabric portion” as the correction coefficient so that each fabric portion is normalized to the maximum output 255 of the camera, for example.

In the first example, the correction coefficient of the fabric A101 is 255/204, the correction coefficient of the fabric B102 is 255/61, and the correction coefficient of the fabric C103 is 255/102.
In the second example, the correction coefficient of the fabric A101 is 255/80, the correction coefficient of the fabric B102 is 255/20, and the correction coefficient of the fabric C103 is 255/40.
Thus, the correction coefficient map image 23 is obtained by obtaining the correction coefficient for each pixel of the output image of the camera 5. In this camera 5, one screen is composed of 640 × 480 pixels.

  A value obtained by dividing the correction coefficient of each pixel by the minimum value of the correction coefficient so that the smallest correction coefficient is 1 is obtained as a normalized correction coefficient of each pixel, and is referred to as a normalized correction coefficient map image 24. It is derived from the correction coefficient normalizing means 18.

  A signal from the bright spot projector 2 obtained by the camera 5 is output as a bright spot image signal 21 by the luminance image receiver 8. Of course, the brightness of each bright spot differs depending on which fabric portion of the object 13 to be measured.

  In the normalizing means 19, each pixel of the luminescent spot image is multiplied by the normalization correction coefficient of each pixel of the normalized correction coefficient map image derived by the correction coefficient normalizing means 18 to each pixel of the bright spot image. Is corrected so as to be uniform and is derived as a normalized bright spot image 25.

  With the above correction, even if a part of the subject has a different reflectance, the maximum value of the bright spot becomes uniform, and the binarization threshold value for extracting the bright spot is obtained over the entire screen. Speed can be increased. Further, bright spots are not extracted, and bright spots are not extracted due to dark spots and dark spots. As a result, highly accurate three-dimensional measurement can be performed on the entire screen.

  The output of the bright spot image correcting means 10 is processed in the same manner as in the conventional example, and the three-dimensional distance information of the object to be measured is measured.

  Next, an example of correction in the case where external light such as sunlight or room light is incident only on a part of the object to be measured and the brightness of the surface of the object to be measured is extremely different is shown as a second example. 5 and FIG. FIG. 5 is a block diagram showing the configuration of the second embodiment. FIG. 6 is an explanatory diagram showing signal waveforms at various parts in the configuration of the second embodiment.

  FIG. 5 shows that in the embodiment shown in FIG. 1, a subtractor A 26, a subtracter B 28, and a low-pass filter 27 are provided between the bright spot image receiver 8 and the background image receiver 9 and the bright spot image luminance correction means 10. It is an expansion. Since other configurations are the same as those of the embodiment shown in FIG. 1, the same reference numerals are given and description thereof is omitted.

  Since the bright spot image 21 and the background image 22 in FIGS. 5 and 6 receive strong external light on a part of the surface of the object to be measured, the influence of external light appears in the lower part of the image. In such a situation, it becomes difficult to process the acquired image, so correction according to this embodiment is performed.

  In FIG. 6, 30 indicates a portion corresponding to the brightness by the background light, and 31 indicates a portion corresponding to the brightness by the external light. Reference numeral 32 denotes a portion corresponding to the brightness of the bright spot. Here, for ease of illustration, the reflectance of the fabric A101 is 75%, the reflectance of the fabric B102 is 25%, and the reflectance of the fabric C103 is 50%.

  The bright image with external light FIG. 6B, which is an output signal of the luminance image receiving unit 8, and the background image with external light, FIG. 6A, which is an output signal of the background image receiving unit 9, are introduced into a subtracter A26 and a subtractor B28, respectively. When the subtractor A26 subtracts the bright spot image B with external light from the background image A with external light and calculates only a positive value, an image signal in which the bright spot portion sinks black is obtained. FIG. 6C.

By passing this signal through the two-dimensional LPF 27 and passing only the low-frequency component, a virtual background image is obtained. FIG. 6D. Similarly, when the background image A with external light is subtracted from the bright image B with external light by the subtractor B28 and only a positive value is calculated, a virtual bright image with only a bright point, FIG. 6E, is obtained. By introducing the virtual background image D and the virtual bright spot image E into the bright spot image luminance correction means 10 and calculating (multiplying the correction coefficient), the normalized bright spot image FIG. obtain.
From the bright spot position information obtained here, the distance measuring means 11 can obtain three-dimensional distance information related to the shape of the object to be measured.

  In the above description, the dot-shaped pattern light is used to acquire the three-dimensional distance information. However, the present invention is not limited to the dot shape, and can be applied when other patterns are used. .

  As described above, according to the present invention, even when the surface of the object to be measured has a partially different reflectance, an image of a bright spot is accurately extracted, and the bright spot image is processed. The obtained three-dimensional shape can be acquired in a shorter calculation time.

  According to the present invention, it is possible to proportionally obtain a reflected bright spot image of an object to be measured having an extremely different reflectance with respect to photographing light, which is difficult to measure with a conventional apparatus, and a range of distance image measurement. It is useful for increasing the number of samples and shortening the measurement processing time, and therefore promotes the use in new fields that have not been possible in the past.

DESCRIPTION OF SYMBOLS 1 Bright spot projector drive circuit 2 Bright spot projector 3 Background light projector drive circuit 4 Background light projector 5 Camera 6 Projector control part 7 Image processing part 8 Bright point image receiving part 9 Background image receiving part 10 Bright point image correction means 11 Distance measurement Means 12 Distance image processing unit 13 Measured object 14 Bright spot projector control signal 15 Background projector control signal 16 Image signal 20 Image 21 by reflected light when visible light is projected By reflected light when infrared light is projected Image 22 Bright spot image 23 Correction coefficient map image 24 Normalized correction coefficient map image 25 Normalized bright spot images 26 and 28 Subtractor 27 LPF
31 Infrared bright spot projection 32 Uniform infrared 101 Fabric A
102 Dough B
103 Fabric C

Claims (4)

A bright spot projector for projecting a bright spot pattern on the object to be measured, and a bright spot image that is arranged at a position away from the bright spot projector and that receives and outputs the bright spot image from the reflected light of the bright spot projection from the target object. A background light projector for projecting uniform light onto the object to be measured at a timing different from that of the bright spot projector, and a camera and an apparatus that obtains three-dimensional distance information by calculating an output signal of the camera; and A controller for controlling the light projection timing of the two light projectors, and combining the bright spot image acquired and output by the camera with the background image, and the brightness of the bright spot image due to the difference in reflectance of the object to be measured A bright spot image acquisition apparatus having an image processing unit for correcting the difference. A background image acquired from a camera that shoots the object to be measured when the background light is projected with uniform light on the object to be measured, and a bright spot image acquired from the camera when a bright spot pattern is projected on the object to be measured. A correction coefficient map image using the reciprocal of the luminance of the background image is created, and the luminance of the bright spot image is corrected by multiplying the correction coefficient of the correction coefficient map image by the previous bright spot image. A bright spot image acquisition method. Two subtractors for subtracting these two kinds of image signals from each other using the background image acquired from the camera at the time of background light projection and the bright spot image acquired from the camera when the bright spot is projected; The bright spot image acquiring apparatus according to claim 1, wherein the output of one subtractor corrects the difference in brightness of the bright spot image by the low-pass component through a low-pass filter and the output of the other subtractor. The image processing unit introduces the background image, a correction coefficient calculating means for matching the luminance of each part of the image output by the camera to the maximum output of the camera, and the correction coefficient so that the correction coefficient becomes a minimum value 1. The bright spot image acquiring apparatus according to claim 1, comprising correction coefficient normalizing means for matching and normalizing means for normalizing the luminance image using a correction coefficient generated by the correction coefficient normalizing means.

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