Source: http://www.google.com/patents/US6897946?ie=ISO-8859-1
Timestamp: 2014-03-17 05:54:31
Document Index: 401687680

Matched Legal Cases: ['art 110', 'art 1010', 'art 111', 'art 5', 'art 5', 'art 6', 'art 6', 'art 206']

Patent US6897946 - Ranger finder device and camera - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsA range finder device, for measuring, when a plurality of projected lights having radiation patterns whose light intensity differs three-dimensional space-wise are irradiated onto an object from a light source on a time-sharing basis to image-pick up reflected light of the projected light from the object...http://www.google.com/patents/US6897946?utm_source=gb-gplus-sharePatent US6897946 - Ranger finder device and cameraAdvanced Patent SearchPublication numberUS6897946 B2Publication typeGrantApplication numberUS 10/420,650Publication dateMay 24, 2005Filing dateApr 22, 2003Priority dateMay 25, 1998Fee statusPaidAlso published asDE69943406D1, EP1006386A1, EP1006386A4, EP1006386B1, EP2306228A1, EP2306229A1, EP2312363A1, EP2312363B1, EP2416197A1, EP2416198A1, EP2416198B1, US6587183, US6704099, US6734951, US20030193657, US20030193658, US20030193659, US20040145722, WO1999061948A1Publication number10420650, 420650, US 6897946 B2, US 6897946B2, US-B2-6897946, US6897946 B2, US6897946B2InventorsKenya Uomori, Takeo Azuma, Atsushi MorimuraOriginal AssigneeMatsushita Electric Industrial Co., Ltd.Export CitationBiBTeX, EndNote, RefManPatent Citations (27), Non-Patent Citations (5), Referenced by (9), Classifications (25), Legal Events (2) External Links: USPTO, USPTO Assignment, EspacenetRanger finder device and cameraUS 6897946 B2Abstract A range finder device, for measuring, when a plurality of projected lights having radiation patterns whose light intensity differs three-dimensional space-wise are irradiated onto an object from a light source on a time-sharing basis to image-pick up reflected light of the projected light from the object with a camera, a distance using the light intensity of an image picked up, characterized in that, with respect to each of a plurality of surfaces including the center of the light source and the center of a lens, there is obtained, in advance, relation between an angle of each projected light from the light source and light intensity ratio in each surface, characterized in that, at the time of actual distance measurement, light intensity of each pixel of the camera is measured, and on the basis of the light intensity thus measured, and relation between the angle and the light intensity ratio on a predetermined surface corresponding to a coordinate position of the pixel measured, there is obtained the angle corresponding to the light intensity of the predetermined pixel thus measured, and characterized in that, on the basis of these light intensity measured, the angles obtained and further two-dimensional coordinate position information on the predetermined pixel on the image, a distance to the object is calculated.
1. A camera for shape measuring or object extracting, comprising:
light-emitting means of irradiating an object with projected light having a specified radiation pattern; and an image-pickup lens for picking up reflected light of said light-emitting means from said object to obtain a depth image using light intensity of an image picked up; wherein said camera has a moveable structure for varying to a predetermined set distance a distance between said light-emitting means and said image-pickup lens; and said predetermined set distance between said light-emitting means and said image-pickup lens is of a magnitude to obtain the depth image. 2. The camera according to claim 1, wherein:
said predetermined set distance between said light-emitting means and said image-pickup lens is realized by said light-emitting means and a main body of said camera, including said image-pickup lens, being relatively slidable; and during use of said camera, said light-emitting means and said main body are caused to slide such that they are spaced apart from each other by the predetermined set distance, whereby said predetermined set distance between said light-emitting means and said camera lens is of the magnitude to obtain the depth image. 3. The camera according to claim 1, wherein:
said predetermined set distance between said light-emitting means and said image-pickup lens is realized by said light-emitting means and a main body of the camera, including said image-pickup lens, being connected together by a hinge configuration; and during use of said camera, the hinge configuration between said light-emitting means and said main body is opened, whereby said predetermined set distance between said light-emitting means and said camera lens is of the magnitude to obtain the depth image. 4. The camera according to claim 1, wherein said light-emitting means irradiate said object with a plurality of projected lights, each light having a different specified radiation pattern than the other lights.
5. The camera according to claim 1, wherein light-emitting means irradiate said object with a flash projecting said light having said specified radiation pattern.
This application is a divisional of U.S. patent application Ser. No. 09/463,530 filed Mar. 30, 2000 now U.S. Pat. No. 6,587,183, which is a U.S. National Phase Application of PCT International Application PCT/JP99/02715, filed on May 24, 1999.
In FIG. 40, reference numerals 101A and 101B denote laser light sources having slightly different wavelengths; 102, a half mirror for synthesizing laser light from the laser light sources having the different wavelengths; 103, a light source control part for controlling light intensity of the laser light source; 104, a rotary mirror for scanning laser light; 105, a rotation control part for controlling the rotary mirror; 106, an object; 107, a lens for forming an image on a CCD; 108A and 108B, light wavelength separation filters for separating light having wavelength from the laser light source; 109A and 109B, CCDs for picking up a monochromatic image; 109C, a CCD for picking up a color image; 110A and 110., signal processing parts for a monochromatic camera; 111, a signal processing part for a color camera; 112, a distance calculation part for calculating a distance or a shape of an object from intensity of laser light photographed by CCDs 109A and 109B; and 113, a control part for adjusting synchronization of the entire device. Hereinafter, the description will be made of the operation of a range finder device thus configured.
The laser light sources 10A and 101B emit laser light having slightly different wavelengths. This laser light is a line light having a light cross-section perpendicular to the scanning direction of a rotary mirror (to be described later), and becomes a line light in the perpendicular direction when a rotary mirror scans in the horizontal direction.
FIG. 41 shows wavelength characteristics for these two light sources.
The reason why two light sources having close wavelengths to each other are used resides in the fact that it is less influenced by dependency of the reflection factor of the object on a wavelength. The laser light emitted from the laser light sources 101A and 101B is synthesized by the half mirror 102, and is scanned on the object 6 by the rotary mirror 104.
The lens 107 forms an image of the object on CCDs 109A, 109B and 109C. The light wavelength separation filter 108A transmits light in wavelength of the light source 10A, and reflects light in another wavelength. The light wavelength separation filter 108B transmits light in wavelength of the light source 101B, and reflects light in another wavelength. As a result, reflected light from the light sources 10A and 101B from the object is photographed by the CCDs 109A and 109B, and light of another wavelength is photographed by the CCD 109C as a color image.
The light source A signal processing part 110A and light source B signal processing part 1010B perform similar signal processing to the output from the CCDs 109A and 109B. The color camera signal processing part 111 performs an ordinary color camera signal processing to the output from the CCD 109C.
FIGS. 43(a) and (b) are explanatory views useful for graphically illustrating the distance calculation. In the figures, the reference character O denotes a center of the lens 107; P, a point on the object; and Q, a position of an axis of rotation of the rotary mirror. Also, for brevity, the position of the CCD 109 is shown turned around on the object side. Also, assuming the length of OQ (base length) to be L, an angle of P as viewed from Q in the XZ plane to be φ, an angle of P as viewed from O to be θ, and an angle of P as viewed from O in the YZ plane to be or, the three-dimensional coordinate of P can be calculated by the following formula (1) from the graphical relation.
Z=D tan θ tan φ/(tan θ+tan φ) (1) X=Z/tan θ Y=Z/tan ω
FIG. 9 is a view illustrating a change in X-coordinate of light intensity in the second embodiment;
(DESCRIPTION OF THE SYMBOLS) 1 Camera
502 Housing 503 Lens
5100 Portion which has been judged to be the background.
The light source control part 5 causes the light sources 2 a and 2 b to alternately emit light for each field period in synchronism with a vertical synchronizing signal of the camera 1. Light sources 2 a and 2 b may include flash light sources 7 and 8 such as xenon flash lamps that are lengthwise arranged and the directions of passive reflection plates behind them are laterally deviated as shown in, for example, FIG. 2(a). FIG. 2(b) is a plan view of FIG. 2(a). The light sources 2 a and 2 b radiate light within ranges A and B respectively. This xenon lamp has a small-sized light emitting portion, and one which can be regarded as a point light source as viewed from above. Further, the light sources 2 a and 2 b are lengthwise arranged, and the distance therebetween is about 1 cm, and these light sources appear as if light was emitted substantially from one point.
An example of a light pattern to be radiated from such light sources is shown in FIG. 3. When light is projected onto a provisional screen, a size of the brightness of the screen surface is shown by a direction ->in the figure. That is, the respective light sources have characteristic properties that the screen surface is brightest at the central axis, and becomes darker toward the marginal portion. It is bright at the center and dark in the marginal portion in this manner because semi-cylindrical passive reflection plates 9 and 10 are located behind the flash light sources 7 and 8. Also, the directions of those semi-cylindrical passive reflection plates 9 and 10 are deviated, and the respective projected light is emitted so that it is partially overlapped.
When a point P in FIG. 1 is set to an attention point, an angle φ of the point P as viewed from the light sources is measured through the use of a luminance ratio obtained from image pickup data when two types of light patterns are irradiated concerning the point P in an image picked up by the camera 1, and the relation of FIG. 5 corresponds to a Y-coordinate value of the point P. In this respect, an assumption is made that the relation of FIG. 5 has characteristic properties that vary depending upon the Y-coordinate value as described above, and that the relationship between the light intensity ratio and an angle φ from the light sources in the horizontal direction has been prepared by a preliminary measurement for each Y-coordinate. Also, an angle θ with respect to the point P as viewed from the camera is determined by the position (that is, pixel coordinate value of the point P) of the image, and a camera parameter (focal length, optical center position of the lens system). Thus, the distance is calculated from die two angles and a distance (base length) between the light source position and the optical center position of the camera in accordance with the principle of triangulation.
Assuming that the optical center of the camera is the origin, setting the optical axis direction of the camera as the Z-axis, the horizontal direction as X-axis, and the perpendicular direction as Y-axis, and assuming an angle, made by the X-axis, of the direction of the attention point as viewed from the light source to be φ, an angle, made by the X-axis, of the direction of the attention point as viewed from the camera to be θ, and the light source position to be (0, −D), that is, the base length to be θ, and the depth value Z of the attention point P can be calculated from the above-described formula (1)
Z=D tan θtan φ/(tan θ−tan φ) According to the present embodiment as described above, a distance is measured by correcting any variations in the light intensity generated by the light sources or the optical system at the time of measuring the distance by means of a range finder using light intensity, whereby it is possible to realize a stable range finder device with high precision capable of implementation by electronic operations.
In this respect, at the front of an infrared camera having a range finder according to the present embodiment, a half mirror or a dichroic mirror and a color camera are arranged, whereby a color image having the same viewpoint as the distance image can be obtained. In this respect, in the distance calculation part according to the present embodiment, the description has been provided where only the distance Z is calculated to output the calculation result as a distance image, but it may be possible to output three-dimensional coordinate data by calculating all three-dimensional coordinate values X, Y and Z from formulas (1) and (2) using an angle ω shown in FIG. 6, and this technique is included in the present invention.
The light source control part 5 causes the light sources 2 a and 2 b to emit light for each field period in synchronism with a vertical synchronizing signal of the infrared camera 1 a. Light sources 2 a and 2 b may include a xenon lamp, which flashes, and has a small-sized light emitting portion, (which can be regarded as a point light source). Also, the light sources 2 a and 2 b are arranged in the vertical direction.
Assuming the optical center of the camera to be the origin, setting the optical axis direction of the camera as the Z-axis, the horizontal direction as the X-axis and the vertical direction as the Y-axis, and assuming an angle, made by the X-axis, of the direction of the attention point as viewed from the light source to be �, an angle, made by the X-axis, of the direction of the attention point as viewed from the camera to be θ, and the light source position to be (0, −D), that is, the base length to be D, the depth value Z of the attention point P can be calculated using the following formula:
Z=D tan θ tan φ/(tan θ−tan φ) The distance calculation part 6 calculates a distance image from a video signal of the camera 1 a. The calculation method may be accomplished in the same manner as in the first embodiment. Another method of performing more accurate measurements is described below. FIG. 8 is a block diagram illustrating the distance calculation part 6. In FIG. 8, the reference numerals 11 a and 11 b denote field memories; 12 a and 12 b, light intensity correction means; 13, light intensity ratio calculation means; and 14, distance conversion means. Hereinafter, the description will be made of the operation of each component.
In this respect, in the distance calculation part according to the present embodiment, a description has been presented where only the distance Z is calculated and the calculation result is outputted as the distance image, but it is possible to calculate all of the three-dimensional coordinate values X, Y and Z using the angle ω shown in FIG. 6 from the following formulas:
Z=D tan θ tan φ/(tan θ−tan φ) X=Z/tan θ Y=Z/tan ω and to output the corresponding three-dimensional coordinate data.
Also, in the above-described embodiment, a description has been provided where the light distributor includes a shutter mechanism such that the object is irradiated with light on a time-shared basis, however, the present invention is not limited thereto. For example, light from the light source includes light having a plurality of frequencies, and the light distributor may be provided with a filter, whereby light having a different wavelength is irradiated from the aperture. Thus; the camera part is provided with a filter and a light-receiving element, capable of distinguishing between these two types of wavelengths, thereby making it possible to irradiate the object with each light having two types of wavelengths at the same time. This reduces the measuring time. In FIG. 10(b), if the wavelength of the semiconductor lasers 201 a and 201 b are different from each other, and the camera part 206 is provided with a filter and a light-receiving element, capable of distinguishing between these two types of wavelengths, it is possible to reduce the measurement time, as described above.
Also, it is impossible to calculate or measure the sizes or dimensions of an object that is image-picked up with a conventionally-known camera unless the distance to the object is known. Also, it has been impossible to know the sizes of the object from a color image that has been picked up.
A light pattern thus obtained is a pattern in which the light intensity varies as shown in FIG. 17. FIG. 18 illustrates the variations in the light intensity in the horizontal X-direction (one dimension). In the α portion of this light pattern, light to be irradiated from the two light sources into the object space becomes bright on the right side in one and bright on the left side in the other, as viewed from each light source. This pattern varies, however, also in the height-wise direction (Y direction).
X=Z/tan θ Y=Z/tan ω
According to the present embodiment as described above, it is possible to generate a plurality of light patterns in a single configuration, and to realize a shape measuring camera with a stable configuration through the use of a straightline shaped strobe light-emitting tube and a shading plate with a hole for a light intensity change pattern.
Lab=√{square root over ({(Xa−xb)2+(Ya−Yb)2+(za−zb)2})}{square root over ({(Xa−xb)2+(Ya−Yb)2+(za−zb)2})}{square root over ({(Xa−xb)2+(Ya−Yb)2+(za−zb)2})}
This enables a small number of light-emitting tubes to emit light as if light were emitted from the same position instead of light-emitting patterns being emitted from positions vertically deviated as shown in FIG. 2, and any measurement error in depth can be reduced.
When the first and second strobes 505 and 506 in the light sources are used, an area P is a portion where information of a distance image cannot be obtained, and when the light sources 543 and 544 are used, an area a is a portion where information of a distance image cannot be obtained. In the same manner as in the foregoing calculation, a distance image A and a color image A (when the first and second strobes 505 and 506 in the light sources are used), and a distance image B and a color image B (when the light sources 543 and 544 are used), are independently calculated respectively in advance. At this time, in the respective images, the portions in the areas p and a are judged to be portions having low luminance from the image data obtained in advance.
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