Optics: measuring and testing – Shape or surface configuration – Triangulation
Reexamination Certificate
2000-04-06
2002-04-09
Font, Frank G. (Department: 2877)
Optics: measuring and testing
Shape or surface configuration
Triangulation
C356S604000
Reexamination Certificate
active
06369899
ABSTRACT:
This application is based upon application No. 11-100635 filed in Japan, the contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a camera for getting information upon three-dimensional shape of an object.
2. Description of the Related Arts
Conventionally, as a device for getting information upon three-dimensional shape of an object, for example, there has been proposed a device for getting the information from a pair of images that have passed through a plurality of photographing lenses, and there has conventionally been proposed a device for detecting distance distribution by projecting light onto an object (or subject) on the basis of the principle of triangulation, as shown in FIG.
23
.
Also, for example, there has been proposed a device for detecting distance distribution by projecting a fringe pattern onto an object and by inputting the fringe pattern by another camera, on the basis of the principle of triangulation, as disclosed in Japanese Laid-Open Patent Publication No. 6-249624.
Also, for example, there has conventionally been proposed a device to seek for an undulation (or up and down) of an object by projecting a lattice pattern onto the object and by observing the object in different angles, in which modified data corresponding to the modified lattice pattern formed in compliance with the undulation of the object is gained (Journal of the Institute of Precision Engineering, 55, 10, 85 (1989)).
Also, for example, there has conventionally been proposed a device for measuring optical distribution by projecting a gray-code pattern with a CCD camera, instead of projecting the lattice pattern, as shown in FIG.
24
.
In order to gain the information upon the three-dimensional shape with the aforementioned device, however, there is need of taking (or photographing) a plurality of images, and the process, subsequent to taking the images, of the information is complex. As a result, a longer time is required for an operation to take an image of the object, and/or a longer time is required for processing the information after taking the image. In other words, it is considered that there is no special problem if the mechanism of the aforementioned device is employed for any measuring device; however, it is considered that it is not suitable to apply the mechanism thereof to any camera.
Therefore, as a device for speedily getting the information upon three-dimensional shape with higher precision, for example, there has been proposed the following device therefor.
Namely, as shown in
FIG. 25
(Source: “Optical Three-Dimensional Measurement,” edited by Toru Yoshizawa, Shin-Gijutsu Communications (or New Technical Communications), page 89, FIGS. 5.2.12
a
), a stripe pattern is firstly projected onto an object (or subject); and the stripe pattern formed on the object is detected at an angle determined in terms of a design relative to the projected stripe pattern; and then the distance distribution of the object is detected from the deformed image of the stripe pattern in compliance with the unevenness (or irregularity) of the object. That is, with respect to a phase of an image measured at each image point, a shift (or swerve, or change) in phase relative to its original stripe is computed. The phase shift includes information upon the height of the object. In this relation, the distance distribution of the object is sought, or determined, from the phase information and its triangulation information. However, there is need of high precision for the detection. Because there is a limitation in density distribution of the stripe pattern or in light intensity thereof, there has been employed a method for seeking the distance distribution of the object by a plurality of images taken with the position of the stripe pattern being shifted bit by bit. Based upon this method, for example, stripe patterns with four shifts in phase of 0°, 90°, 180° and 270°, are projected.
By the way, as a measuring device, there has been conventionally provided a commercial product in which a slitting light is scanned. According to the measuring device, it takes several hundreds of milliseconds to scan the slitting light for the purpose of getting the information upon three-dimensional shape information.
Meanwhile, there has conventionally been provided a digital camera in which a plurality of images are consecutively taken in case that the photographing mode is a successively photographing mode and in which the image is recorded (or stored) upon a memory card after the plurality of images are taken (or after the object is successively photographed). However, the digital camera is not a camera for getting information upon three-dimensional shape of an object.
According to the aforementioned device and method, however, if the stripe pattern which has a plurality of stripes has only one cycle, the density distribution becomes so rough that it is not possible to heighten the precision for getting the information upon three-dimensional shape of an object.
In order to solve this technical problem, there have conventionally been taken measures in which a stripe pattern with several cycles is projected onto the object. In this case, however, if the object has a deep distance distribution, it is not possible to identify which particular stripe of the stripe pattern a particular piece of information upon the stripe of the stripe pattern corresponds to. Namely, in this case, the angle used in the triangulation may be interpreted as a different angle (or a wrong angle), by taking a particular stripe of the stripe pattern for a strip thereof corresponding to a different ordinal number (or a wrong ordinal number) of the plurality of stripes thereof. As a result, a wrong distance distribution is gained.
More specifically, for example, as shown in
FIG. 28
, a point “A” which locates on a fore plane “P
1
” becomes a piece of information upon the third stripe of the plurality of stripes of the stripe pattern; on the other hand, a point “B” which locates on a rear plane “P
2
” becomes another piece of information upon the fourth stripe thereof. However, if it is not possible to accurately identify which ordinal number of stripe the particular stripe of the plurality of stripes of the stripe pattern corresponds to, the points “A” and “B” can not be distinguished from each other, only on the basis of information upon the image sensed by its light receiving part.
Furthermore, in case of increasing the number of points for detection by increasing the number of stripes in a particular stripe pattern for the purpose of enhancing the precision in distance distribution, if a particular stripe is wrongly identified in its ordinal number of stripes, it also leads to a false detection of the information upon three-dimensional shape of the object.
Under such a circumstance, for the purpose of reducing the misdetection of the information thereupon, and for the purpose of increasing the accuracy for identifying any particular stripe of the plurality of stripes of the stripe pattern, applicant has proposed the following improvement of the stripe pattern to be projected (see, for example, Japanese Patent Application No. 11-87124, not laid open yet).
Namely, according to the improvement, for example, a pattern having a plurality of frequencies, and/or a pattern having a plurality of codes and stripes, and/or a light having a colored pattern, is/are projected onto an object. Further, according to the improvement, not only such a pattern with a gradation, but also a marker to be able to identify a particular position or location on the pattern, are projected onto the object.
According to the aforementioned device and the improvement, however, if it is not possible to accurately identify which ordinal number of stripe of the plurality of stripes forming the stripe pattern a particular stripe corresponds to, wrong data, or a piece of wrong information upon three-dimensional shape of the object, is gained. Namely, no matter which types of patterned lights
Minolta Co. , Ltd.
Morrison & Foerster / LLP
Punnoose Roy M
LandOfFree
Camera with projector for selectively projecting pattern lights does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Camera with projector for selectively projecting pattern lights, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Camera with projector for selectively projecting pattern lights will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2828223