３次元映像情報メディア技術 表面反射率が部位によって異なる物体の３次元形状計測

A lot of plumbings such as gas pipes and water pipes exist in public utilities, factories, power plants and so on. The use of an omni-directional camera that can take images of 360° in surroundings at a time is effective for the pipe inspection. However, shape measurement is difficult only with the omni-directional camera. Therefore, in this paper, we propose a reconstruction method of piping shape by using an omni-directional camera and an omni-directional laser with a light section method and a structure from motion. Our method calculates 3-D coordinates by the light section method. The individual measurement data is integrated with the information of camera motion estimated by the structure from motion technique. We construct a triangular mesh by using 3-D Delaunay triangulation. By texture-mapping, a 3-D Pipe model is generated. The validity of the proposed method is shown through experiments.

System calibration, which usually involves complicated and time-consuming procedures, is crucial for any 3-D shape measurement system. In this work, a novel systematic method is proposed for accurate and quick calibration of a 3-D shape measurement system we developed based on a structured light technique. The key concept is to enable the projector to "capture" images like a camera, thus making the calibration of a projector the same as that of a camera. With this new concept, the calibration of structured light systems becomes essentially the same as the calibration of traditional stereovision systems, which is well established. The calibration method is fast, robust, and accurate. It significantly simplifies the calibration and recalibration procedures of structured light systems. This work describes the principle of the proposed method and presents some experimental results that demonstrate its performance.

Confocal 3-D imaging technique is a newly developed technique and widely used in many fields of research and development. It is to utilize light intensity sensitive measuring technique. Confocal 3-D profile measurement system is widely used in high resolution inspection. For high precision 3-D imaging inspection in confocal measuring system, light source acts a very important role in system resolution and accuracy. In order to improve measuring repeatability and stability, to reduce measurement error, and to lower the light source stability requirement and cost, this paper studied light source fluctuation effect to confocal imaging measurement; deduced depth response model function; analyzed system error caused by light source fluctuation; and presented a new scheme to reduce the affection of light source fluctuation. Theoretical analysis and experiment result verified that light source fluctuation should be considered and eliminated in very high resolution confocal 3-D shape measurement system.

Nano-level 3-D measurement is one of the key technologies for the current and next generation of production systems for semi-conductors, LCDs and nano-devices. To meet with these applications, “Wide range nano-level 3-D shape measurement method using combination of RGB laser lights” has been developed. It measures the height of nano-objects from the combination of RGB LED lights combinations. To analyze the combination of RGB lights, the color analysis method on xy-color plane has been introduced. In this method, the color changes on xy-color plane means the height changes. Experimental system to measure the micro-meter heights using RGB lightings has been developed, and succeeded to measure the 50 nm step and 500 nm step samples.

An automatic image processing system for measuring instantaneous, whoie field of velocity vectors was developed. This system is connected with the classical flow visualization technique (tracer injection method) and sophisticated image processing technique. The measurement system consists of a laser light source, a TV camera, a laser optical disk recorder and an image processor interfaced with a 16 bit micro-computer. The tracer particles injected into the liquid flow are illuminated using the pulsed laser light sheet and are tracked by the TV camera. The images recorded on the laser disk are later replayed and sent to the image processor, and instantaneous velocity vectors of whole flow field is automatically calculated. To explore the ability and usefulness of this system the complex flow fields have been investigated.

Innovative airglow instrument based on constant photon count control

This paper presents a patented three-dimensional (3D) shape measurement system, ReCreator, which is mainly composed of two CCD cameras and a random pattern projector with fixed geometry. It can work in the binocular mode, where the stereo image pair is utilized to reconstruct the 3D point cloud in the common field of view of the two cameras; while in the monocular mode, each single camera and the random pattern projector constitute a measuring unit respectively to alleviate the highlight and occlusion effect. The design and the calibration of the random pattern projector, which is the key ingredient for enabling the system, are discussed in detail. The system algorithms are partially implemented with NVIDIA Graphics Processing Units (GPU) in the Compute Unified Device Architecture (CUDA) programming environment, which proves effective to accelerate the computation. Experiments are conducted to validate the precision, rapidity and data integrity of the measurement system.

Visualization of 3D variable in time object based on data gathered by active measurement system

The process of recognizing a vehicle involves detection of the vehicle, recognition of the vehicle model, and identification of the vehicle. The process of vehicle identification involves identification of the vehicle itself, such as by recognition of the license plate on the vehicle. License plate recognition can have many applications, such as conventional traffic volume measurements, vehicle identification for charging purposes on toll roads, the determination of in-contract vehicles in parking garages, and monitoring the arrival of specific vehicles. For these applications, the authors have developed a sensing method that produces little wobbling of captured images of moving vehicles and generates halation-free images under wide-ranging environmental conditions from bright direct sunlight to poorly illuminated conditions at night. The method involves the use of a beam splitter to divide incident rays into two directions, a transmitted beam and a reflected beam of different light intensities, and synthesizing two captured images using CCD devices from each beam, thus producing fluctuation-free images of a wide dynamic range even when the subject is moving. The experimental sensing device is capable of shooting scenes with a dynamic range of 1.5 × 104 at a shutter speed of 1/1000 second. Simultaneously, a license plate recognition method was developed. A prototype license plate recognition system was also developed using the experimental sensing device. The system achieved a 98.7% recognition rate on 466 images of moving vehicles, which demonstrates its effectiveness as a license plate recognition system. © 2000 Scripta Technica, Syst Comp Jpn, 31(11): 82–91, 2000

Research and application on shape meter are introduced, especially in China. A self-made MPIBPST (multi-roll-piece inner bore piezomagnetic sensor type) shape meter roll for cold-rolled steel strip was applied in to the industrial test. MPIBPST means that one shape meter roll is made up of some roll-picesce, there are two bores in each roll picesce, and each inner bore contains one piezomagnetic sensor. In order to combine with the work of the shape meter roll and display the real-time shape, a shape measurement system based on TMS320F2812 is designed and developed. Measurement principle on shape, hardware and software design are described in detail. The running in the industrial field for about six months shows that shape meter has the advantages of signal stability and credibility, stronger anti-interference ability, high-precision, and meets the measuring requirements on the industrial field. The successful application of the MPIBPST shape meter lays a solid foundation for the further research on AFC (Automatic Flatness Control System) in China. The design on this system also has a reference value for similar work.

In this paper, we discuss the performance of a 3-D shape measurement system in aim of applying the system for improving the cosmesis of the prosthetic hand gloves and covers. The human hand shape is a complex continued closed shell that requires multi dimensional shots to be united for reproducing precise full surface model in 3-D CG and CAD software. The building process requires visual observation of the model and manual operation, which involves skill, to create high precision model in limited time. This paper reports the experimental consideration of the effect of marker properties (color, thickness, background color) that upsets the surface configuration. The characteristic and evaluation method of the deformation and the experimental results are shown.

Non-sinusoidal phase error is common in structured light three-dimensional (3D) shape measurement system, thus we perform theoretical and experimental analyses of such error. The number of non-sinusoidal waveform errors in a 2\pi phase period is the same as the number of steps of the phase-shifting algorithm; no errors occur within the one-phase period. Based on our findings, a new structured light method, the linear sinusoidal phase-shifting method (LSPS), that is resistant to non-sinusoidal phase error is proposed. Experiments show that the non-sinusoidal waveform error is reduced to an almost negligible level (0.001 rad) using the proposed LSPS.

System calibration is crucial for any 3-D shape measurement system. An accurate method is proposed to calibrate a 3-D shape measurement system based on a structured light technique. The projector is treated as a camera to unify the calibration procedures of a structured light system and a well-established stereo vision system. The key to realizing this method is to establish a highly accurate correspondence between camera pixels and projector pixels and generate digital micromirror device (DMD) image sets for projector calibration. A phase-shifting method is used to accomplish this task. A precalibrated lookup table and a linear interpolation algorithm are proposed to improve the accuracy of the generated DMD image, and accordingly improve the accuracy of the projector calibration and the 3-D measurement. Some experimental results are presented to demonstrate the performance of the system calibration.

3-D shape measurement systems by contactless method are required in the quality inspections of metal molds and electronic parts in industrial fields. A grating projection method with phase-shifting method has advantages of high precision and high speed. Recently, the size of a BGA (ball grid array) becomes smaller. So the pitch of a grating pattern projected onto the specimen should be smaller. In conventional method, fringe pattern is projected using an imaging lens. The focal depth becomes smaller in the case of reduced projection. It is therefore difficult to project a grating pattern with small pitch onto an object with large incident angles. Authors recently proposed a light source stepping method using a linear LED device. It is easy to shrink the projected grating pitch with a lens because this projection method does not use an imaging lens. The pitch of the projected grating depends on the width of the light source. There is a limit to shrink the projected grating pitch according to the size of the LED chip. In this paper, a small pitch fringe projection method with multiple linear fiber arrays for 3D shape measurement is proposed. The width of the fiber array is 30μm. It is one digit smaller than the width of the LED chip. The experimental result of 3-D shape measurement with small pitch projection with large incident angles is shown.

Three-dimensional (3D) shape measurement system with binary defocusing technique can perform high-speed and flexible measurements if binary fringe patterns are defocused by projector properly. However, the actual defocusing degree is difficult to set, and the fringe period is difficult to determine accordingly. In this study, we present a square-binary defocusing parameter selection framework. First, we analyze the fringe formation process mathematically. The defocusing degree is quantified and manipulated by using the focusing distance of projector, which is calibrated by point spread function measurement. To optimize parameter selection, single-point sinusoidal error is modeled as the objective function for the evaluation of the defocusing effect. We verify the correctness by using different parameter combinations and object measurements in our experiments. The appropriate defocusing parameters can be easily obtained according to the analysis of practical system setup, which improves the quality and robustness of the system.