JPH0585846B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a distance image acquisition device using a range finder used in a three-dimensional visual device.

(Prior Art) A range finder (Japanese Patent Application No. 59-197414) has been proposed as a device for determining the three-dimensional position of an object using an image input from a television camera. An example of a method for determining the distance from a camera to an object using this range finder will be briefly explained with reference to FIG.

A parallel white light source from a light source 1 passes through a lens 2 and is projected onto an object 4, which is split into spectrum lights from red to blue-violet by a diffraction grating 3. Light with a wavelength λ is projected onto a point P on the object surface at an angle θ from the normal line (an angle α from the two-axis direction), and this is imaged by the camera 5 and sensed at a position x on the sensor. At this time, if the coordinates of point P are (X, Z),
Z is determined by equation (1).

Z=(X ₀ −Z ₀ tanα)(tanβ−tanα) (1) The value of β can be known from the position x on the image sensor. Since there is a relationship x=c tan β where c is a constant, equation (1) can be written as follows.

Z=(X ₀ −Z ₀ tanα)/(X/c−tanα)
...(1') The value of α is determined by knowing the wavelength λ of the light being sensed, sinθ−sinθ=±nλ/d ...(2) (where d is the grating spacing of the diffraction grating, and n is the order (usually = 1), and by knowing the angle between the diffraction grating and the Z axis. The wavelength of the light reflected by each point on the object is determined by considering the camera 5 as a color camera, whose two sensors have different spectral sensitivities σ ₁ (λ) and σ ₂ (λ), and when the point P is imaged. When the outputs of the pixels are I ₁ and I ₂ respectively, the output ratio R=I ₁ /(I ₁ +I ₂ )=σ ₁ (λ)/σ ₁ (λ) + σ ₂ (
λ)
…(3) holds, so the function f(λ)=σ ₁ (λ)/(σ ₁ (λ)+σ ₂ (λ))…
By determining σ ₁ (λ) and σ ₂ (λ) so that (4) is a monotone function of λ, λ can be determined from the ratio of outputs. λ obtained in this way is the above σ
It is used to obtain . In the manner described above, the distance Z can be obtained from two simultaneously captured images.

(Problems to be Solved by the Invention) According to the prior art described above, in order to obtain the distance Z from the images input by two sensors to the object at each pixel, the equation (4) () can be used for λ. When, () Expression (2) is expressed as θ, () Z is obtained by Expression (1).

You need to follow the steps as follows. In this case, it is necessary to accurately know the spectral sensitivities σ ₁ (λ) and σ ₂ (λ) of the two sensors, the relationship between angles θ and σ, the relationship between x and β, X ₀ , Z ₀ , etc. , sensor filter, diffraction grating position, camera, etc., all relationships must be recalculated.

An object of the present invention is to create a distance image in which the distance Z can be obtained for each pixel by simply inputting the image in advance, without any need to accurately measure the positional relationship of the components as described above. The objective is to provide an acquisition device.

(Means for Solving the Problems) The present invention projects a spectral pattern separated by a diffraction grating or the like onto an object, captures this image using sensors with different spectral sensitivities, and identifies the object for each pixel. A range finder that calculates the distance to a camera includes ratio image calculation means for calculating a ratio from the outputs of a plurality of A/D converters that convert a plurality of outputs of the sensor into digital values, and a ratio image calculation means for calculating a ratio from the outputs of a plurality of A/D converters that convert the plurality of outputs of the sensor into digital values, Calibration data calculation means for placing a flat object on a plane and calculating calibration data from the ratio data that is the output of the ratio image calculation means; This is a distance image acquisition device that obtains a distance image from a sensor output of a range finder, and includes distance calculation means for calculating the distance to an object for each pixel from the obtained calibration data.

(Function) FIG. 3 shows the arrangement when implementing the present invention. The arrangement of the light source 1, lens 2, diffraction grating 3, and camera 5 is the same as in FIG. Consider two planes, plane 6 and plane 7, in the space of an object. Further, a white board is placed at the position of the plane 6, an image is captured, and R in equation (3) is determined for each pixel. Since the Z coordinate of plane 6 is Za,
Equation (1) becomes Za=(X ₀ −Z ₀ tanα)/(tanβa−tanα) ……(5). α is a function of R, and the z-coordinate of the imaging position with the camera has a relationship with the angle βa as shown in equation (6) with c as a constant, so x _a = c・tanβa ...(6) x with respect to plane 6 _a is a function of R x _a (R)
can be written as, and by transforming equation (5), equation (7) can be obtained.

Z _a (x _a (R)/c−tanα(R))=X ₀ −Z ₀ tanα(R
)
...(7) In exactly the same way, next place a white board at the position of plane 7,
When an image is captured, the relationship between R and x _b (R) is obtained,
Equation (8) is obtained.

Z _a (x _b (R)/c−tanα(R))=X ₀ −Z ₀ tanα(R
)
...(8) From equations (7) and (8), the unknowns X ₀ −Z ₀ tanα(R) and tannα
By finding (R) and substituting it into equation (1'),
Equation (9) is obtained.

Z=Z _a Z _b (x _b (R)−x _a (R))/{(Z _a Z _b )・x+
(Z _b・x _b (R) − Z _a・x _a (R)} ...(9) In other words, the relationship between the ratio R and the x coordinate x _a ( R) and
If x _b (R) is calculated, in actual measurement,
It can be seen that the Z coordinate of the object can be obtained by equation (9) using the x coordinate of each pixel and the ratio R obtained from the captured image. There is no need to explicitly know the values of Y coordinate, X ₀ , Z ₀ , α(R), etc.

(Example) An example of the present invention based on the above operation will be described with reference to FIG.

Image data acquired by two sensors with different spectral sensitivities of the camera 5 are transferred to A/D converters 8 and 9.
The image data is stored in two image memories 10 and 11 via the image memory 10 and 11. The ratio image calculation circuit 12 calculates the ratio R for each pixel in the image memories 10 and 11 according to equation (3), and stores the ratio image in the ratio image memory 13. switch 1
4 switches the flow of read data from the image memory 13.

When an image is acquired by placing a white board on the plane 6, the calibration data calculation circuit 15 calculates and holds the ratio R and x-coordinate calibration data x _a (R) on the plane 6 from the ratio image stored via the switch 14. . Similarly,
When an image is acquired by placing a white board on the plane 7, the calibration data calculation circuit 16 calculates and holds the ratio R and x-coordinate calibration data x _b (R) on the plane 7 from the stored ratio image via the switch 14. .

When actually measuring the distance to an object, the distance calculation unit 17 calculates the ratio R for each image from the ratio image memory 13 by
Calibration data according to readout formula (a) along with coordinate values
While referring to x _a (R) and x _b (R), the distance Z is determined and written to the distance image memory. As a result of the above series of operations, the distance Z from the camera 5 to the object 4 is obtained in each pixel of the distance image memory 18.

(Effects of the Invention) As described in detail above, by using the present invention, various parameters necessary for obtaining the distance to each pixel can be measured from the range finder shown in Japanese Patent Application No. 59-197414. A distance image can be easily obtained using calibration data obtained by inputting images twice.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention;
FIG. 2 is an explanatory diagram of the range finder shown in Japanese Patent Application No. 59-197414, and FIG. 3 is an explanatory diagram showing the arrangement when calibrating the present invention. 1...Light source, 2...Range, 3...Diffraction grating,
4...Object, 5...Camera, 6,7...Plane with calibration, 8,9...A/D converter, 10,1
1... Image memory, 12... Ratio image calculation circuit, 1
3... Ratio image memory, 14... Switch, 15,
16...Calibration data calculation circuit, 17...Distance calculation section, 18...Distance image memory.

Claims (1)

[Claims] 1 In a range finder, a spectral pattern separated by a diffraction grating or the like is projected onto an object, this image is captured by sensors with different spectral sensitivities, and the distance to the object is determined for each pixel.
ratio image calculation means for calculating a ratio from the outputs of a plurality of A/D converters that convert the plurality of outputs of the sensors into digital values; and a planar object placed at two different distances from the camera including the sensor; Calibration data calculation means for calculating calibration data at each distance from the ratio data that is the output of the calculation means;
In the scene of distance measurement, the sensor output of the range filter includes distance calculation means for calculating the distance to the object for each pixel from the output of the ratio image calculation means and the calibration data obtained by the calibration data calculation means. A distance image acquisition device that obtains a distance image from.