LCD Projector Research Articles

Implementation of phase-shifting moiré profilometry on a low-cost commercial data projector

In phase-shifting moiré profilometry, grid lines are projected onto an object, and the deformed projection is imaged onto a second grid to obtain moiré fringes. Grid noise is removed by translating both grids simultaneously in their own plane, and fringe phase-shifts are obtained by changing the relative distance between the two grids. From three or more phase-shifted moiré fringe patterns, object surface height is calculated on all pixel points of the camera which records the moiré fringe patterns. Classically, translation of the grids is performed mechanically. Recently, we have introduced a method using two liquid crystal light modulators to perform high-resolution phase-shifting moiré topography without any mechanically moving parts. We now describe, how this new method can be implemented using a low-cost consumer product LCD projector. We show how the different LCD panels can be addressed, and how fast grid noise averaging can be implemented using a standard computer graphics board. Resolution measurements and application examples are presented on objects of different sizes.

Flexible Calibration of a Portable Structured Light System through Surface Plane

For a portable structured light system, it must be easy to use and fiexible. So the inconvenient and expensive equipment for calibration such as two or three orthogonal planes or extra fixed equipment should not be considered. For the purpose of fast 3D acquisition, the projection matrices of a portable structured light system should be estimated. This paper proposes a flexible calibration method to meet the requirements of the portable structured light system through a surface plane. A calibration board is attached to the surface plane, and a reference pattern is also projected by an LCD projector onto the surface plane. The camera observes the surface plane at a few different positions. Then, the world-to-image point pairs for the camera and projector are obtained based on the cross ratio and epipolar geometry, and the system is thus calibrated. The experiments conducted for the proposed calibration method demonstrate its accuracy and robustness.

Flexible Calibration of a Portable Structured Light System through Surface Plane

For a portable structured light system, it must be easy to use and fiexible. So the inconvenient and expensive equipment for calibration such as two or three orthogonal planes or extra fixed equipment should not be considered. For the purpose of fast 3D acquisition, the projection matrices of a portable structured light system should be estimated. This paper proposes a flexible calibration method to meet the requirements of the portable structured light system through a surface plane. A calibration board is attached to the surface plane, and a reference pattern is also projected by an LCD projector onto the surface plane. The camera observes the surface plane at a few different positions. Then, the world-to-image point pairs for the camera and projector are obtained based on the cross ratio and epipolar geometry, and the system is thus calibrated. The experiments conducted for the proposed calibration method demonstrate its accuracy and robustness.

Examining gender differences in attitudes toward interactive classroom communications systems (ICCS)

An interactive classroom communication system (ICCS) involves the use of remote devices that permit all students in a class to respond to multiple choice questions displayed on a LCD projector. After responses are clicked in, the results are instantly aggregated and displayed in chart form. The purpose of this study was to examine gender differences in attitudes toward ICCSs for 659 secondary school students. The initial results suggested that male students had significantly more positive attitudes than female students with respect to student involvement, assessment, and perceived learning. However, a number of these differences disappeared when computer comfort level and type of use were added as covariates. Male students still perceived that ICCSs improved the overall learning process more than female students regardless of computer comfort level or type of use.

Flexible Calibration of a Portable Structured Light System through Surface Plane

For a portable structured light system, it must be easy to use and flexible. So the inconvenient and expensive equipment for calibration such as two or three orthogonal planes or extra fixed equipment should not be considered. For the purpose of fast 3D acquisition, the projection matrices of a portable structured light system should be estimated. This paper proposes a flexible calibration method to meet the requirements of the portable structured light system through a surface plane. A calibration board is attached to the surface plane, and a reference pattern is also projected by an LCD projector onto the surface plane. The camera observes the surface plane at a few different positions. Then, the world-to-image point pairs for the camera and projector are obtained based on the cross ratio and epipolar geometry, and the system is thus calibrated. The experiments conducted for the proposed calibration method demonstrate its accuracy and robustness.

IMPLEMENTATION OF A DRIVING SIMULATOR BASED ON A STEWART PLATFORM AND COMPUTER GRAPHICS TECHNOLOGIES

This paper describes works related to the development of a land vehicle driving simulator, which consists of a Stewart platform as its motion device and a computer graphical system as its visual component. The main task is to enable the pilot-experience the sensation of motion while driving the vehicle under the constraint of the platform's finite working space. Involved are works such as establishment of the vehicle dynamical model, analysis of the forces acting on the pilot, and application of the washout algorithm and human motion sensation models. With the results from these works, appropriate motion trajectory commands for the platform can be generated. Besides the physical motion part, a computer graphical system is installed to generate scenes that give visual cues. While following the pilot's steering signals and matching the platform's motion, the visual system creates animation scenes of the environment, which are shown on a large screen in front of the pilot through an LCD projector. To test the completed system, different pilots operate it and give subjective assessments. Also, gyros are mounted on the platform to measure its responses to motion commands. Here some experimental results are summarized and discussed.

The PLVC display color characterization model revisited

AbstractThis work proposes a study of the Piecewise Linear assuming Variation in Chromaticity (PLVC) display color characterization model. This model has not been widely used as the improved accuracy compared with the more common PLCC (Piecewise Linear assuming Chromaticity Constancy) model is not significant for CRT (Cathode Ray Tube) display technology, and it requires more computing power than this model. With today's computers, computational complexity is less of a problem, and today's display technologies show a different colorimetric behavior than CRTs. The main contribution of this work is to generalize the PLVC model to multiprimary displays and to provide extensive experimental results and analysis for today's display technologies. We confirm and extend the results found in the literature and compare this model with classical PLCC and Gain‐Offset‐Gamma‐Offset models. We show that using this model is highly beneficial for Liquid Crystal Displays, reducing the average error about a third for the two tested LCD projectors compared with a black corrected PLCC model, from 3.93 and 1.78 to respectively 1.41 and 0.54 ΔE units. © 2008 Wiley Periodicals, Inc. Col Res Appl, 33, 449–460, 2008

Improved speckle projection profilometry for out-of-plane shape measurement

An improved speckle projection profilometry that combines the projection of computer generated random speckle patterns using an ordinary LCD projector and the two-dimensional digital image correlation technique for in-plane displacements measurement is proposed for accurate out-of-plane shape and displacement measurements. The improved technique employs a simple yet effective calibration technique to determine the linear relationship between the out-of-plane height and the measured in-plane displacements. In addition, the iterative spatial domain cross-correlation algorithm, i.e., the improved Newton-Raphson algorithm using the zero-normalized sum of squared differences correlation criterion and the second-order shape function was employed in image correlation analysis for in-plane displacement determination of the projected speckle patterns, which provides more reliable and accurate matching with a higher correlation coefficient. Experimental results of both a regular cylinder and a human hand demonstrate that the proposed technique is easy to implement and can be applied to a practical out-of-plane shape and displacement measurement with high accuracy.

Product Rapid Design for Customer Individual Requirements

Based on product configuration and modular design, a product rapid design method for customer individual requirements was proposed. Aiming at the product configuration correlation of this product rapid design method, we classify the product in accordance with the product functional modular classification principle, define the correlation between the functional modules, set up the correlation matrix between each module and recognize the customer demand of individual product configuration immediately by using the exclusion algorithm. At last, taking multimedia LCD projector as paradigm, we verify this method.

Flexible method for structured light system calibration

We propose a flexible technique to easily calibrate a structured light system, in which only two patterns are required: a paper checkerboard printed on a laser printer and attached to a surface plane, and a pattern image of a checkerboard, which is projected on the surface plane by a LCD projector. We treat the projector as a second camera; then the problem of calibrating the structure light system becomes equivalent to calibrating a stereovision system. The key to our technique is to make the projector able to see the calibration checkerboard like a camera. For that purpose, two approaches are proposed, called the black-and-white checkerboard method and the red-and-blue checkerboard method. Both computer simulation and real data are used to test the proposed technique, and very good results are obtained. (C) 2008 Society of Photo-Optical Instrumentation Engineers.

Lesions of the Cerebellar Nodulus and Uvula Impair Downward Pursuit

We studied sinusoidal (SIN) and step-ramp (SR) pursuit in two rhesus monkeys, before and after surgical lesions of the cerebellar nodulus and uvula (Nod/Uv). Eye movements were recorded using the magnetic field scleral search coil method. Pursuit targets were generated by an LCD projector and back-projected onto a tangent screen in an otherwise dark room. After the Nod/Uv lesions, both monkeys showed a reduced eye velocity during downward pursuit (SIN: 42% decrease in M1, 91% decrease in M2; SR: 37% decrease in M1, 85% decrease in M2). For SR, the decrease was seen only for the closed-loop response; initial eye acceleration did not change (P>0.05). Upward pursuit gains increased for SIN (M1: 9%, M2: 11%); they decreased for SR (M1: 27%, M2: 18%), but to a lesser degree than for downward pursuit. Horizontal pursuit was little changed in M1 but was reduced in one direction in M2, the animal with the larger lesion. The deficit in downward tracking was limited to foveal pursuit; ocular following of random-dot stimuli was retained, even when the target subtended only several degrees. Our findings support a critical role for the Nod/Uv in vertical pursuit, particularly for sustained downward pursuit. Finally, in both monkeys, the lesion increased spontaneous upward ocular drift in the dark (mean prelesion, 1.43 degrees/s; postlesion, 5.92 degrees/s), suggesting a role for the Nod/Uv in holding the eyes still and in the genesis of downbeat nystagmus.

“It is just easier to do what you did before…”: An Update on Internet Use in Secondary Social Studies Classrooms in Indiana

This study replicated a 1999 survey study of classroom Internet use by social studies teachers (6–12) in Indiana. The 1999 study indicated that although 80% wished to be using it more often, respondents' Internet use was little more than “glorified information gathering.” The present study modified the same instrument to survey a random sample of secondary social studies teachers in Indiana in order to determine what, if any, changes had occurred in the intervening 6 years. Data indicated improvement across most barriers (e.g., connectivity, training, access to equipment) identified in the previous study, but 70% of respondents still wished to be using the Internet more often. The Internet was still most commonly used to “gather background information for the lessons I teach.” The present study created the Internet Use Scale (IUS) and the IUS score was used to divide respondents into quartiles. The first quartile (higher-order users) was compared to the fourth quartile (lower-order users). Significant differences were found for: hours of training, experience, number of fast-connection computers in their instructional lab, and access to LCD projectors. Results of the present study support Ertmer's (2005) finding that teachers' pedagogical beliefs are the single most important factor in implementing technology in the classroom.

Different Dynamics of Performance and Brain Activation in the Time Course of Perceptual Learning

Perceptual learning is regarded as a manifestation of experience-dependent plasticity in the sensory systems, yet the underlying neural mechanisms remain unclear. We measured the dynamics of performance on a visual task and brain activation in the human primary visual cortex (V1) across the time course of perceptual learning. Within the first few weeks of training, brain activation in a V1 subregion corresponding to the trained visual field quadrant and task performance both increased. However, while performance levels then saturated and were maintained at a constant level, brain activation in the corresponding areas decreased to the level observed before training. These findings indicate that there are distinct temporal phases in the time course of perceptual learning, related to differential dynamics of BOLD activity in visual cortex.

441 高エネルギX線CT装置を用いた現物融合ボクセル流体解析技術の開発と液晶プロジェクタへの適用(OS23.計算工学およびCAEの最新応用(3),オーガナイズドセッション)

441 高エネルギX線CT装置を用いた現物融合ボクセル流体解析技術の開発と液晶プロジェクタへの適用(OS23.計算工学およびCAEの最新応用(3),オーガナイズドセッション)

3810 液晶プロジェクタ用光学部品の狭板間二方向衝突空冷の検討(S59-2 柔軟媒体ハンドリングと画像形成システム(2),21世紀地球環境革命の機械工学:人・マイクロナノ・エネルギー・環境)

3810 液晶プロジェクタ用光学部品の狭板間二方向衝突空冷の検討(S59-2 柔軟媒体ハンドリングと画像形成システム(2),21世紀地球環境革命の機械工学:人・マイクロナノ・エネルギー・環境)

Real-time Motion Analysis Using CCD Camera

This paper proposes a device that simultaneously computes and displays the biomechanical quantities, such as joint moments, joint forces and the center of gravity point, at the same time with the symmetric motion of subjects with respect to a sagittal plane. These biomechanical quantities are computed in real-time based on the inverse dynamics, using the marker positions obtained by real-time image processing of the body movement which is captured by a CCD camera. Then these biomechanical quantities are displayed in real-time on a screen by a LCD projector, and accordingly the subject can objectively recognize the quality of the motion by seeing these physical quantities during the motion. In the application of this real-time motion analyzer to the analysis of bow motion, bending and stretching and sit-to-stand motion, it is shown that this device is advantageous for the coaching and the self-education of an optimal motion based on the body mechanics.

Projecting two words with one machine: Presenting two different visual stimuli using just one projector without viewers’ noticing the duality

A new method, named the fMORI technique, for presenting two different visual stimuli using just one video projector without the viewers' noticing the duality is introduced along with several sample applications of this presentation method. The LCD projectors available now have three color LCD panels aligned differently in terms of their polarization, polarizing differently the green and magenta (red plus blue) components of its emitting image. Therefore, two visual stimuli either in green or in magenta projected on thesame screen canbe observed separately by subjects wearing an appropriate polarizing filter. This is a variation of the MORI technique (Mori, 2003, 2007b) but it requires only one video projector rather than two. Full-color movies cannot be presented with the fMORI technique, but it may be utilized in various research areas in which only static monochrome visual stimuli, such as words or numbers, are used.

A pilot study on pupillary and cardiovascular changes induced by stereoscopic video movies

BackgroundTaking advantage of developed image technology, it is expected that image presentation would be utilized to promote health in the field of medical care and public health. To accumulate knowledge on biomedical effects induced by image presentation, an essential prerequisite for these purposes, studies on autonomic responses in more than one physiological system would be necessary. In this study, changes in parameters of the pupillary light reflex and cardiovascular reflex evoked by motion pictures were examined, which would be utilized to evaluate the effects of images, and to avoid side effects.MethodsThree stereoscopic video movies with different properties were field-sequentially rear-projected through two LCD projectors on an 80-inch screen. Seven healthy young subjects watched movies in a dark room. Pupillary parameters were measured before and after presentation of movies by an infrared pupillometer. ECG and radial blood pressure were continuously monitored. The maximum cross-correlation coefficient between heart rate and blood pressure, ρmax, was used as an index to evaluate changes in the cardiovascular reflex.ResultsParameters of pupillary and cardiovascular reflexes changed differently after subjects watched three different video movies. Amplitudes of the pupillary light reflex, CR, increased when subjects watched two CG movies (movies A and D), while they did not change after watching a movie with the real scenery (movie R). The ρmax was significantly larger after presentation of the movie D. Scores of the questionnaire for subjective evaluation of physical condition increased after presentation of all movies, but their relationship with changes in CR and ρmax was different in three movies. Possible causes of these biomedical differences are discussed.ConclusionThe autonomic responses were effective to monitor biomedical effects induced by image presentation. Further accumulation of data on multiple autonomic functions would contribute to develop the tools which evaluate the effects of image presentation to select applicable procedures and to avoid side effects in the medical care and rehabilitation.

Toward a 3D Multispectral Scanner: An Application to Multimedia

A stereoscopic system based on a multispectral camera and an LCD projector uses multispectral information for 3D object reconstruction. By linking 3D points to a curve representing the spectral reflectance, the system gives a physical representation of the matter that's independent from illuminant, observer, and acquisition devices

A novel configuration of LCD projectors for efficient orthogonal polarization of two projected views

In this paper, a novel configuration of LCD projectors for efficiently polarized stereoscopic projection with improved light efficiency is presented. In the proposed scheme, polarization orientations of the analyzers in the LCD engine of one projector are rotated by 90° with respect to those of the other one, so it causes to rotate orientations of polarized outputs by 90° as well as to change operational modes of LCD panels from the normally black mode to the normally white mode or vice versa. Then, by exchanging the green color components between the modified and original LCD projectors, two orthogonally polarized views for stereoscopic projection could be obtained without use of external polarizers. Analysis on the operational mode conversions of the LCD engines with rotation of the analyzers is discussed and its experimental results are provided.