Structured Light Field by Two Projectors Placed in Parallel for High-Speed and Precise 3D Feedback

In recent years, it is required to acquire three-dimensional information at high speed in various fields. Previously, a structured light field (SLF) method for high-speed three dimensional measurement in 1 ms was proposed by our group. However, the SLF method has a drawback of worse depth estimation error by several tens millimeters. In this paper, a novel method to generate SLF with two projectors placed in parallel is proposed. This arrangement could produce bigger pattern change depending on the depth and made more precise estimation possible. The depth estimation experiments for precision evaluation and dynamic projection mapping experiment successfully demonstrated precise depth estimation with the error of several millimeters and high-speed estimation within 1 ms, though the measurement range was limited to approximately 100 mm.

High-Speed Depth-Normal Measurement and Fusion Based on Multiband Sensing and Block Parallelization

A wide range of research areas have high expectations for the technology to measure 3D shapes, and to reconstruct the shape of a target object in detail from multiple data. In this study, we consider a high-speed shape measurement technology that realizes accurate measurements in dynamic scenes in which the target object is in motion or deforms, or where the measurement system itself is moving. We propose a measurement method that sacrifices neither measurement density nor accuracy while realizing high speed. Many conventional 3D shape measurement systems employ only depth information to reconstruct a shape, which makes it difficult to capture the irregularities of an object’s surface in detail. Meanwhile, methods that measure the surface normal to capture 3D shapes can reconstruct high-frequency components, although low-frequency components tend to include integration errors. Thus, depth information and surface normal information have a complementary relationship in 3D shape measurements. This study proposes a novel optical system that simultaneously measures the depth and normal information at high speed by waveband separation, and a method that reconstructs the high-density, high-accuracy 3D shape at high speed from the two obtained data types by block division. This paper describes the proposed optical system and reconstruction method, and it evaluates the computation time and the accuracy of reconstruction using an actual measurement system. The results confirm that the high-speed measurement was conducted at 400 fps with pixel-wise measurement density, and a measurement accuracy with an average error of 1.61 mm.

Development of Birefringence Confocal Laser Scanning Microscope and its Application to Sample Measurements

A new laser microscope is developed to obtain depth-direction birefringence information of optically anisotropic samples, which cannot be obtained by a conventional polarization microscope. As a result, birefringence tomographic images are now available and the method should be helpful for sample evaluations.

3D Measurement of Large Structure by Multiple Cameras and a Ring Laser

This paper presents an effective mobile three-dimensional (3D) measurement system that can obtain measurements from the inside of large structures such as railway vehicles, elevators, and escalators. In the proposed method, images are acquired by moving measurement equipment composed of a ring laser and two cameras. From the acquired images, accurate cross-sectional shapes, which are obtained via a light-section method by each camera, are integrated into a unified coordinate system using pose estimation based on bundle adjustment. We focus on the method of separately extracting the information necessary for the two processes – the light-section method and pose estimation – from the acquired images. The laser areas used for the light-section method are detected by a bandpass color filter. Further, a new block matching technique is introduced to eliminate the influence of the laser light, which causes incorrect detection of corresponding points. Through an experiment, we confirm the validity of the proposed 3D measurement method.