Stereo camera

Ricoh has developed stereo cameras capable of responding to various needs of three-dimensional measurement. It has done so by combining high-precision packaging technology for integrated sensors and lenses, calibration technology, and parallax computation technology.

Features of Ricoh Stereo camera

A stereo camera in general detects depth information of a subject by using parallax of two cameras aligned left and right.

image:Example output image
Varying distance to the subject is expressed as different colors
Figure 1: Example output image

In order to accomplish high accuracy in the depth information acquired by the stereo camera, it is necessary to correct optical distortion of the cameras and make two cameras positioned in parallel.  Ricoh has succeeded in producing stereo cameras that are highly precise and compact. This was made possible by fusing several technologies accumulated at Ricoh: optical technology that evaluates optical characteristic in high accuracy, image processing technology that corrects the optical characteristic fast and accurately, and packaging technology that enables high-precision assembly, building a proprietary calibration system in the process.  As a result, our stereo cameras can be built into various devices to accurately capture the presence and size of target objects. Application is possible in such fields as factory automation (FA), automotive, and security.

Two types of stereo camera for respective uses

Ricoh has developed two types of stereo camera with respective advantages.

High-precision stereo camera
With this stereo camera, lens distortion is corrected by highly accurate image processing, using Ricoh’s proprietary calibration system. For a lens mount, a C-mount is employed so that the lens specification can be changed flexibly, enabling the stereo camera to be utilized in various scenarios. Furthermore, parallax calculation processing is executed within the camera, so that a monochrome image and a distance image can be acquired simultaneously at 30fps. By jointly using information of both the monochrome image and the distance image during recognition processing, precise and fast recognition processing can be achieved.

iamge: High-precision stereo camera in which C-mount lens is interchangeable
Figure 2: High-precision stereo camera in which C-mount lens is interchangeable

Ultra-compact stereo camera
This ultra-compact stereo camera achieves a high-precision range performance of ±3% at a distance of 20cm in an unprecedentedly compact and lightweight package, about the size of a thumb. This was made possible by a highly compact integrated sensor and laser welding technology. The integrated sensor has two image sensors, which are necessary for a stereo camera, aligned on one substrate integrally. Development of this integrated sensor made configuration of the stereo camera simple and the overall size of the camera become compact. In addition, with the laser welding technology, Ricoh has successfully eliminated misalignments due to shrinkage during adhesive hardening. Quality fluctuations resulting from varying amounts of applied adhesive have also been eliminated. Unlike adhesives that require time to harden, laser welding enables instant assembly, making it possible to significantly reduce the time required for assembly. As a result, ultra-compact stereo camera can be built into various devices to accurately capture the presence and size of target objects.

image:Exterior of camera head realized in thumb-sized, ultra-compact stereo camera
Figure 3: Exterior of camera head realized in thumb-sized, ultra-compact stereo camera

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Ricoh stereo camera applications

Usage scenario 1: employing a high-precision stereo camera in robot-picking system

By utilizing the high-precision stereo camera, three-dimensional information of a subject can be obtained accurately. This makes it possible to construct a stable robot-picking system.

image:Usage scenario in robot-picking
Figure 4: Usage scenario in robot-picking

Usage scenario 2: embedding an ultra-compact stereo camera in small spaces

Extraordinarily compact, our stereo cameras can be installed in small spaces, inside walls for example. When combined with recognition processing based on distance images and luminance images, highly precise high-speed image recognition becomes possible, enabling use in security applications such as screening passersby.

image:Usage scenario for embedding in small spaces
Figure 5: Usage scenario for embedding in small spaces

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