Journal articles: 'Projector'

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Tanaka, Kenta, Motoyasu Sano, Yumi Horimai, Hideyoshi Horimai, and Yusuke Aoki. "Geometric Correction Method Applying the Holographic Ray Direction Control Technology." Journal of Robotics and Mechatronics 33, no. 5 (October 20, 2021): 1155–68. http://dx.doi.org/10.20965/jrm.2021.p1155.

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In recent years, there has been an increasing need for larger screens and higher definition displays, while projectors are becoming smaller and cheaper. Furthermore, an ultra-short-throw projector that can display on a large screen while significantly reducing the distance between the projector and screen is being developed. However, ultra-short-throw projectors are required to be precisely aligned with the screen, and if the screen is not flat, the projected image becomes distorted. Therefore, geometric correction projection technology is attracting attention for projection on curtains and the walls of living rooms instead of screens for realizing the correction of distortion during projection with ultra-short-throw projectors, projection mapping, signage, etc. We focused on developing a hologram with perfect command of the ray. Conventional geometry-correction systems are expensive systems that require a personal computer and a camera. In this study, we developed a geometric correction method applying holographic ray direction control technology to control a holographic ray at a low cost and in real time. In this paper, we studied the exposure technology and proposed a ray-direction control technology that combines a scanning laser projector that uses a hologram and a micro electro mechanical systems mirror. We also proposed and demonstrated the basic principle of a holographic surface projector (HSP), which uses hologram geometry correction technology. Finally, we constructed a geometrically corrected hologram exposure system using a depth camera and conducted geometrically corrected projection experiments.

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Vetoshkin, A. M., and A. A. Shum. "Strictly oblique projectors and their properties." FORESTRY BULLETIN 24, no. 5 (October 2020): 122–27. http://dx.doi.org/10.18698/2542-1468-2020-5-122-127.

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In this paper, strictly oblique projectors are defined as projectors that cannot be represented as the sum of two projectors, one of which is a nonzero orthoprojector. A theorem is proved that each projector can be represented in a unique way as the sum of a strictly oblique projector and an orthoprojector. The properties of such projectors are given. For example: if the projector is strictly oblique, then its Hermitian adjoint is also strictly oblique; the rank of a strictly oblique projector is at most n/2, where n is the order of the projector matrix; the property of the projector to be strictly oblique is preserved with a unitary similarity. The work is a continuation of the previous work of the authors, the main result of which is such a matrix expression for an arbitrary projector: where A and B are two matrices of full rank whose columns define range and the null space of this projector. Based on this result, the article shows that the strictly oblique part of any projector P is given by the expression: P(P – P+P)+P. And equality P = P(P – P+P)+P is a criterion that the projector P is a strictly oblique projector. The decomposition of the projector obtained in the work is applied to the practical problem of oblique projection onto the plane

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Zhang, Bao Long, Wei Qi Ding, Shao Jing Zhang, and Hui Shuang Shi. "Realization of Automatic Keystone Correction for Smart Mini Projector Projection Screen." Applied Mechanics and Materials 519-520 (February 2014): 504–9. http://dx.doi.org/10.4028/www.scientific.net/amm.519-520.504.

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With the rapid development of mobile internet, the projector becomes the terminal of mobile internet because of the network module embedded in smart projectors, which can provide a more convenient viewing experience. For traditional mini projector just as simple display equipment, the integration of Android operating system makes mini projector smarter, it is equivalent to a simple PC with projection function. This paper discusses the projection screen keystone distortion phenomenon of mini projector equipped with Android operating system under limiting projection environment because of different placement angle and how to eliminate the above-mentioned distortion, after elaborating the software and hardware architecture of smart mini projector, it focuses upon an analysis on how to achieve automatic correction of the projection screen using the digital acceleration sensor in hardware driver of the Android operating system.

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Wu, Lifang, Lidong Zhao, Meng Jian, Yuxin Mao, Miao Yu, and Xiaohua Guo. "EHMP-DLP: multi-projector DLP with energy homogenization for large-size 3D printing." Rapid Prototyping Journal 24, no. 9 (November 12, 2018): 1500–1510. http://dx.doi.org/10.1108/rpj-04-2017-0060.

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Purpose In some three-dimensional (3D) printing application scenarios, e.g., model manufacture, it is necessary to print large-sized objects. However, it is impossible to implement large-size 3D printing using a single projector in digital light processing (DLP)-based mask projection 3D printing because of the limitations of the digital micromirror device chips. Design/methodology/approach A multi-projector DLP with energy homogenization (EHMP-DLP) scheme is proposed for large-size 3D printing. First, a large-area printing plane is established by tiling multiple projectors. Second, the projector set’s tiling pattern is obtained automatically, and the maximum printable plane is determined. Third, the energy is homogenized across the entire printable plane by adjusting gray levels of the images input into the projectors. Finally, slices are automatically segmented based on the tiling pattern of the projector set, and the gray levels of these slices are reassigned based on the images of the corresponding projectors. Findings Large-area high-intensity projection for mask projection 3D printing can be performed by tiling multiple DLP projectors. The tiled projector output energies can be homogenized by adjusting the images of the projectors. Uniform ultraviolet energy is important for high-quality printing. Practical implications A prototype device is constructed using two projectors. The printable area becomes 140 × 210 mm from the original 140 × 110 mm. Originality/value The proposed EHMP-DLP scheme enables 3D printing of large-size objects with linearly increasing printing times and high printing precision. A device was established using two projectors to practice the scheme and can easily be extended to larger sizes by using more projectors.

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Schöning, Johannes, Markus Löchtefeld, Michael Rohs, and Antonio Krüger. "Projector Phones." International Journal of Mobile Human Computer Interaction 2, no. 3 (July 2010): 1–14. http://dx.doi.org/10.4018/jmhci.2010070101.

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With the miniaturization of projection technology, the integration of tiny projection units into mobile devices is no longer fiction; therefore, such integrated projectors in mobile devices could make mobile projection ubiquitous. These phones will have the ability to project large-scale information onto any surfaces in the real world, and by doing so, the interaction space of the mobile device can be considerably expanded. In addition, physical objects in the environment can be augmented with additional information, which can support interaction concepts that are not even possible on modern desktop computers today. The authors believe that mobile camera-projector units can form a promising interface type for mobile Augmented Reality (AR) applications, thus, this paper identifies different application classes of such interfaces. In addition, different spatial setups of camera and projector units will have an effect on the possible applications and the interaction space with the focus on the augmentation of real word objects in the environment. This paper presents two examples of applications for mobile camera-projector units and different hardware prototypes that allow augmentation of real world objects.

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Shen, Tzung-Sz, and Chia-Hsiang Menq. "Digital Projector Calibration for 3-D Active Vision Systems." Journal of Manufacturing Science and Engineering 124, no. 1 (April 1, 2000): 126–34. http://dx.doi.org/10.1115/1.1418694.

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3-D active vision systems that project artificial structured light for coordinate measurements have been adopted in many industrial applications. With advances of electronic projection display technology, the digital projector is becoming an important component of various 3-D active vision systems. However, current projector models or structured light calibration techniques for 3-D active vision systems are limited to stripe-type structured light and the majority of them do not consider projector lens distortion. In order to overcome these limitations, a digital projector calibration method is developed to calibrate light beams projected from all pixel elements of a digital projector. Since the digital projector is fully programmable, various structured light patterns can be projected for coordinate acquisition, whose models can be obtained by interpolating parameters of light beams that synthesize the structured light patterns. With proper interpolation functions, experimental results indicate that the projector lens distortion can be successfully compensated and measurement errors are significantly reduced. When the digital projector is moved, a simple rigid body transformation calibration method is developed to rapidly obtain the transformation without re-calibrating the projector. The precision of the 3-D active vision system using the proposed digital projector calibration method and rigid body transformation calibration technique is experimentally evaluated.

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Hong-jie, Guo, and Du Fu-zhou. "Real-time Projection Method for Augmented Reality Assisted Assembly." MATEC Web of Conferences 175 (2018): 02026. http://dx.doi.org/10.1051/matecconf/201817502026.

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Recently, the augmented reality technology has become a useful tool for assembly guidance. The projectors have been always used as virtual image output devices. In most situations, real-time and dynamic images projection is essential due to that the components to be assembled are randomly placed and movable. However, the cameras and the projectors are placed in different relative positions, making it difficult to project real time images when we are using augmented reality for assembly. A novel method based on the system of binocular cameras and projector was proposed here to overcome the limitation. We established a method to get the relations of coordinate transform among camera coordinate system, projector coordinate system and world coordinate system based on real-time internal parameter matrix of the projector that we derived. Obtaining the pose information of the cameras without any designed markers in real world was also realized, which is the key technology for the camera-projector assembly visualization system. An assembly experiment of cable laying was conducted and the results showed that using the proposed method the real-time projection for augmented reality assisted assembly was realized.

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Byun, JungHyun, and Tack-Don Han. "PPAP: Perspective Projection Augment Platform with Pan–Tilt Actuation for Improved Spatial Perception." Sensors 19, no. 12 (June 12, 2019): 2652. http://dx.doi.org/10.3390/s19122652.

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In this paper, we propose PPAP, an augmented reality platform with an actuated projector for dynamic user-perspective projection. In PPAP, a stationary camera is used jointly with a pan–tilt motorized projector-camera unit. With the servo control of the steerable pan–tilt system, the system is able to continuously orient itself to match the user’s view center of the projection-mapped surface. This provides users with greatly widened viewing angles in the augmented scene, when compared to the stationary projection. Through user studies, in which users judged the size and distance of a projected virtual object, we verified that the perspective projection with the actuated projector helps users better understand the spatial relationship of the virtual object in the augmented scene in terms of depth perception.

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Motta, Thiago, Manuel Loaiza, Alberto Raposo, and Luciano Soares. "Kinect Projection Mapping." Journal on Interactive Systems 5, no. 3 (December 30, 2014): 1. http://dx.doi.org/10.5753/jis.2014.722.

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Spatial augmented reality allows users to create a projected virtual environment on irregular surfaces. This demands an accurate Camera-Projector calibration process in order to produce precise 3D information to match the real object. This paper presents a framework to process data achieved from a calibration of a Kinect-Projector system in visualization applications, allowing the user to create an augmented reality environment without having extensive process of the Camera-Projector calibration, while maintaining a precise calibration to the projection on irregular surfaces. Additionally, different calibration techniques were evaluated in order to demonstrate the better approaches.

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Liu, Zhen, Ming Zhu, and Jian Yu. "The Experimental Research on Tiled Multiple Projectors Displaying Based on ICC Mechanism." Applied Mechanics and Materials 262 (December 2012): 80–85. http://dx.doi.org/10.4028/www.scientific.net/amm.262.80.

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The research on the color uniformity of the tiled multiple projectors display systems gets more and more attention. In this paper, taking the tiled two-projector display system as a case, the color calibration method based on ICC color management mechanism was proposed and used to achieve the color uniformity the non-overlapping projected region firstly. And the sectoring parabola interpretation algorithm was used to achieve the color uniformity of the overlapping projected region. The research content of this paper includes: ①The ICC profile of the projector based on matrix model was calculated and generated; ②The ICC profile of the projector based on 3-dimensions lookup table model was calculated and generated; ③The color-matching precision of the above two types of ICC profiles were compared by the color space conversion experiment, and the feasibility of color calibration method of the non-overlapping projected region based on ICC mechanism was verified; ④Finally, the feasibility of color calibration method of the overlapping projected region based on sectoring parabola interpretation algorithm was verified by Quest3D development platform.

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Choi, Eunbin, Younghyeon Park, and Byeungwoo Jeon. "An Implementation of Drone-Projector: Stabilization of Projected Image." Electronic Imaging 2020, no. 3 (January 26, 2020): 332–1. http://dx.doi.org/10.2352/issn.2470-1173.2020.3.mobmu-331.

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A drone-projector equipped with a beam projector mounted on a drone has been investigated in order to develop a projector which can overcome restriction of place on which an image is projected. For the stability, the drone-projector requires its mass to be centered, and the additional weights related to projector should be within the payload of the drone. In addition to this requirement, the drone-projector should be designed to minimize the distortion of image caused by 3D translations or rotations of a drone during its hovering due to vibration of propellers, or global positioning system (GPS) errors. In this paper, we consider rotation of a droneprojector which makes the projected image tilted, keystoned, and shifted. To overcome this problem, we propose a software-based stabilization method which pre-corrects the image to be projected based on flight information. Our experimental results show that the distortion of the projected image due to rotations of the proposed drone-projector is attenuated by applying our stabilization method.

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Yakno, Marlina, Junita Mohamad-Saleh, Mohd Zamri Ibrahim, and W. N. A. W. Samsudin. "Camera-projector calibration for near infrared imaging system." Bulletin of Electrical Engineering and Informatics 9, no. 1 (February 1, 2020): 160–70. http://dx.doi.org/10.11591/eei.v9i1.1697.

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Advanced biomedical engineering technologies are continuously changing the medical practices to improve medical care for patients. Needle insertion navigation during intravenous catheterization process via Near infrared (NIR) and camera-projector is one solution. However, the central point of the problem is the image captured by camera misaligns with the image projected back on the object of interest. This causes the projected image not to be overlaid perfectly in the real-world. In this paper, a camera-projector calibration method is presented. Polynomial algorithm was used to remove the barrel distortion in captured images. Scaling and translation transformations are used to correct the geometric distortions introduced in the image acquisition process. Discrepancies in the captured and projected images are assessed. The accuracy of the image and the projected image is 90.643%. This indicates the feasibility of the captured approach to eliminate discrepancies in the projection and navigation images.

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Yamauchi, Masaki, and Tomohiro Yendo. "Light field display using wavelength division multiplexing." Electronic Imaging 2020, no. 2 (January 26, 2020): 101–1. http://dx.doi.org/10.2352/issn.2470-1173.2020.2.sda-101.

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We propose a large screen 3D display which enables multiple viewers to see simultaneously without special glasses. In prior researches, methods of using a projector array or a swinging screen were proposed. However, the former has difficulty in installing and adjusting a large number of projectors and the latter cases occurrence of vibration and noise because of the mechanical motion of the screen. Our proposed display consists of a wavelength modulation projector and a spectroscopic screen. The screen shows images of which color depends on viewing points. The projector projects binary images to the screen in time-division according to wavelength of projection light. The wavelength of the light changes at high-speed with time. Therefore, the system can show 3D images to multiple viewers simultaneously by projecting proper images according to each viewing points. The installation of the display is easy and vibration or noise are not occurred because only one projector is used and the screen has no mechanical motion. We conducted simulation and confirmed that the proposed display can show 3D images to multiple viewers simultaneously.

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Gordon, Marsha, and Dino Everett. "Dusting Off that Old Projector: Preservation through Projection." American Archivist 84, no. 1 (March 1, 2021): 139–64. http://dx.doi.org/10.17723/0360-9081-84.1.139.

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ABSTRACT “Dusting Off that Old Projector: Preservation through Projection” makes the case that institutions that hold film prints and projectors—especially rarities, one-offs, and nonstandard gauges—should consider projecting films in an effort to preserve and perpetuate knowledge about the history of film technology. The authors use the success of Home Movie Day as a model for considering preservation through projection and to question absolutist protective strategies. Their aim is to expand the way that archivists, scholars, and the general public think about the significance of unusual film formats and equipment in relation to film history.

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Teubl, Fernando, Marcio Cabral, Marcelo Zuffo, and Celso Kurashima. "Analysis of a Scalable Multi-Projector System for Virtual Reality Environments." International Journal of Virtual Reality 12, no. 1 (January 1, 2013): 15–29. http://dx.doi.org/10.20870/ijvr.2013.12.1.2855.

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Virtual reality environments with multi-projector systems provide better visual quality, higher resolution and more brightness than traditional single-projector systems. Moreover, using multiple low-cost projectors is economically advantageous in comparison to an expensive high-end projector for equivalent visual performance. This article presents the research and development of a scalable multiprojection system that enables the construction of virtual reality systems with a large number of projectors and graphics computers, and that is capable of achieving a high resolution display. We demonstrate the viability of such system with the development of a camera-based multiprojector system library called FastFusion, which automatically calibrates casually aligned projectors to properly blend different projections. Our system software improves known algorithms in the literature for projector calibration and image blending. As a result, FastFusion improves system scalability and calibration reliability. In a detailed analysis of the visual performance of FastFusion in a CAVE system with three walls, eighteen projectors and nine computers, we achieved a satisfactory result for variance in geometric calibration and for graphics performance. Thus, our library is suitable for building complex projector systems and with retina resolution.

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Sharma, Atul, Sushil Raut, Kohei Shimasaki, Taku Senoo, and Idaku Ishii. "Visual-Feedback-Based Frame-by-Frame Synchronization for 3000 fps Projector–Camera Visual Light Communication." Electronics 10, no. 14 (July 8, 2021): 1631. http://dx.doi.org/10.3390/electronics10141631.

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This paper proposes a novel method for synchronizing a high frame-rate (HFR) camera with an HFR projector, using a visual feedback-based synchronization algorithm for streaming video sequences in real time on a visible-light communication (VLC)-based system. The frame rates of the camera and projector are equal, and their phases are synchronized. A visual feedback-based synchronization algorithm is used to mitigate the complexities and stabilization issues of wire-based triggering for long-distance systems. The HFR projector projects a binary pattern modulated at 3000 fps. The HFR camera system operates at 3000 fps, which can capture and generate a delay signal to be given to the next camera clock cycle so that it matches the phase of the HFR projector. To test the synchronization performance, we used an HFR projector–camera-based VLC system in which the proposed synchronization algorithm provides maximum bandwidth utilization for the high-throughput transmission ability of the system and reduces data redundancy efficiently. The transmitter of the VLC system encodes the input video sequence into gray code, which is projected via high-definition multimedia interface streaming in the form of binary images 590 × 1060. At the receiver, a monochrome HFR camera can simultaneously capture and decode 12-bit 512 × 512 images in real time and reconstruct a color video sequence at 60 fps. The efficiency of the visual feedback-based synchronization algorithm is evaluated by streaming offline and live video sequences, using a VLC system with single and dual projectors, providing a multiple-projector-based system. The results show that the 3000 fps camera was successfully synchronized with a 3000 fps single-projector and a 1500 fps dual-projector system. It was confirmed that the synchronization algorithm can also be applied to VLC systems, autonomous vehicles, and surveillance applications.

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Gao, Yuan, Yuyun Zhao, Le Xie, and Guoyan Zheng. "A Projector-Based Augmented Reality Navigation System for Computer-Assisted Surgery." Sensors 21, no. 9 (April 22, 2021): 2931. http://dx.doi.org/10.3390/s21092931.

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In the medical field, guidance to follow the surgical plan is crucial. Image overlay projection is a solution to link the surgical plan with the patient. It realizes augmented reality (AR) by projecting computer-generated image on the surface of the target through a projector, which can visualize additional information to the scene. By overlaying anatomical information or surgical plans on the surgery area, projection helps to enhance the surgeon’s understanding of the anatomical structure, and intuitively visualizes the surgical target and key structures of the operation, and avoid the surgeon’s sight diversion between monitor and patient. However, it still remains a challenge to project the surgical navigation information on the target precisely and efficiently. In this study, we propose a projector-based surgical navigation system. Through the gray code-based calibration method, the projector can be calibrated with a camera and then be integrated with an optical spatial locator, so that the navigation information of the operation can be accurately projected onto the target area. We validated the projection accuracy of the system through back projection, with average projection error of 3.37 pixels in x direction and 1.51 pixels in y direction, and model projection with an average position error of 1.03 ± 0.43 mm, and carried out puncture experiments using the system with correct rate of 99%, and qualitatively analyzed the system’s performance through the questionnaire. The results demonstrate the efficacy of our proposed AR system.

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Zhao, Wu-Xiang, Han-Le Zhang, Qing-Lin Ji, Huan Deng, and Da-Hai Li. "Aerial Projection 3D Display Based on Integral Imaging." Photonics 8, no. 9 (September 9, 2021): 381. http://dx.doi.org/10.3390/photonics8090381.

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We proposed an aerial projection 3D display based on integral imaging. It is composed of a projector, a lens-array holographic optical element (HOE), and two parabolic mirrors. The lens-array HOE is a diffraction grating and is made by the volume holography technique. The lens-array HOE can be produced on a thin glass plate, and it has the optical properties of a lens array when the Bragg condition is satisfied. When the display beams of the element image array (EIA) are projected on the lens-array HOE, 3D images can be reconstructed. The two parabolic mirrors can project 3D images into the air. The Bragg-unmatched light simply passes through the lens-array HOE. Therefore, the aerial projection 3D images appear to be imaged in the air without any medium. In the experiment, a BenQ projector was used for the projection of 3D images, with a resolution of 1600 × 1200. The diameter and the height of each parabolic mirror are 150 mm and 25 mm, respectively. The inner diameter of the parabolic mirror is 40 mm. The 3D images were projected in the air, and the experimental results prove the correctness of our display system.

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Din, I., H. Anwar, I. Syed, H. Zafar, and L. Hasan. "Projector Calibration for Pattern Projection Systems." Journal of Applied Research and Technology 12, no. 1 (February 2014): 80–86. http://dx.doi.org/10.1016/s1665-6423(14)71608-6.

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Chen, Jun, Qingyi Gu, Tadayoshi Aoyama, Takeshi Takaki, and Idaku Ishii. "Blink-Spot Projection Method for Fast Three-Dimensional Shape Measurement." Journal of Robotics and Mechatronics 27, no. 4 (August 20, 2015): 430–43. http://dx.doi.org/10.20965/jrm.2015.p0430.

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<div class=""abs_img""> <img src=""[disp_template_path]/JRM/abst-image/00270004/13.jpg"" width=""300"" /> Blink-spot projection method</div> We present a blink-spot projection method for observing moving three-dimensional (3D) scenes. The proposed method can reduce the synchronization errors of the sequential structured light illumination, which are caused by multiple light patterns projected with different timings when fast-moving objects are observed. In our method, a series of spot array patterns, whose spot sizes change at different timings corresponding to their identification (ID) number, is projected onto scenes to be measured by a high-speed projector. Based on simultaneous and robust frame-to-frame tracking of the projected spots using their ID numbers, the 3D shape of the measuring scene can be obtained without misalignments, even when there are fast movements in the camera view. We implemented our method with a high-frame-rate projector-camera system that can process 512 × 512 pixel images in real-time at 500 fps to track and recognize 16 × 16 spots in the images. Its effectiveness was demonstrated through several 3D shape measurements when the 3D module was mounted on a fast-moving six-degrees-of-freedom manipulator. </span>

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Ke, Ying Jie, Li Jun Li, and Kai Yong Jiang. "Foot Shape Reconstruction Based on a Monocular System Using Structured Light Projection." Applied Mechanics and Materials 16-19 (October 2009): 340–46. http://dx.doi.org/10.4028/www.scientific.net/amm.16-19.340.

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Reverse engineering has an increasing use in shoemaking process for rapid prototyping of shoe lasts. Foot shape reconstruction is one of the most important techniques in custom-made scheme. A system for reconstruction a foot shape from its 2D views using a coded structured light projection combining with the optical triangulation method is presented. A set of multiple gray coded patterns are projected to the target object through a projector and the distorted stripes patterns produced by its surface are captured by a digital camera. By adopting the optical triangulation method with the projector-camera parameters known in advance, the foot shape surface is reconstructed. The results show that the implemented system is able to reconstruct dense and precise 3D foot shapes.

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Jenny, Bernhard, Tom Patterson, and Lorenz Hurni. "Flex Projector–Interactive Software for Designing World Map Projections." Cartographic Perspectives, no. 59 (March 1, 2008): 12–27. http://dx.doi.org/10.14714/cp59.245.

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Flex Projector is a free, open-source, and cross-platform software application that allows cartographers to interactively design custom projections for small-scale world maps. It specializes in cylindrical, and pseudocylindrical projections, as well as polyconical projections with curved parallels. Giving meridians non-uniform spacing is an option for all classes of projections. The interface of Flex Projector enables cartographers to shape the projection graticule, and provides visual and numerical feedback to judge its distortion properties. The intended users of Flex Projector are those without specialized mathematical expertise, including practicing mapmakers and cartography students. The pages that follow discuss why the authors developed Flex Projector, give an overview of its features, and introduce two new map projections created by the authors with this new software: the A4 and the Natural Earth projection.

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Zhao, Xue Jin, and Cheng Rui Zhang. "A New Camera and Projector Calibration Method Based on Discrete Computation." Applied Mechanics and Materials 229-231 (November 2012): 1171–75. http://dx.doi.org/10.4028/www.scientific.net/amm.229-231.1171.

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This paper presents a novel method for the calibration of camera and projector based on discrete computation, which uses a linear moving chessboard and project plane to get a calibration database for camera and projector. The camera database contains multi-layers data of the captured chessboard corners and their corresponding practical coordinates in the system. Then by using this database and interpolation algorithm, we can calculate the accurate position for each given pixel position in the captured image. After this we change the chessboard with a white scene and project a chessboard image to the plane. By capturing the projected image and computing the practical position for the corners in the image, we can get a relationship between practical coordinates and the projected image pixels. So another database for the project image and the practical coordinates is established. By using these two databases, we can define the light line for the pixels in a camera captured image and projected image, which can be used for 3D scanning system and other industrial systems, like mask-image projection stereo lithography rapid prototyping system.

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Kang, WANG, DUAN Jie, ZHOU Jianhong, WANG Chen, and FU Yuegang. "Design on projection objective of portable projector." Journal of Applied Optics 40, no. 2 (2019): 130–33. http://dx.doi.org/10.5768/jao201940.0205003.

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Horisaki, Ryoichi, and Jun Tanida. "Compact compound-eye projector using superresolved projection." Optics Letters 36, no. 2 (January 5, 2011): 121. http://dx.doi.org/10.1364/ol.36.000121.

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Gelšvartas, Julius, Rimvydas Simutis, and Rytis Maskeliūnas. "Projection Mapping User Interface for Disabled People." Journal of Healthcare Engineering 2018 (2018): 1–6. http://dx.doi.org/10.1155/2018/6916204.

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Difficulty in communicating is one of the key challenges for people suffering from severe motor and speech disabilities. Often such person can communicate and interact with the environment only using assistive technologies. This paper presents a multifunctional user interface designed to improve communication efficiency and person independence. The main component of this interface is a projection mapping technique used to highlight objects in the environment. Projection mapping makes it possible to create a natural augmented reality information presentation method. The user interface combines a depth sensor and a projector to create camera-projector system. We provide a detailed description of camera-projector system calibration procedure. The described system performs tabletop object detection and automatic projection mapping. Multiple user input modalities have been integrated into the multifunctional user interface. Such system can be adapted to the needs of people with various disabilities.

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Adamczyk, Marcin. "Temperature Compensation Method for Raster Projectors Used in 3D Structured Light Scanners." Sensors 20, no. 20 (October 12, 2020): 5778. http://dx.doi.org/10.3390/s20205778.

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Raster projectors are commonly used in many various measurement applications where active lighting is required, such as in three-dimensional structured light scanners. The effect of temperature on the raster projector, in some conditions, can lead to significant deterioration of the measurements performed with such a scanner. In this paper, the outcomes of several experiments concerning the effects of temperature on raster projectors are presented. The described research is focused on the thermal deformations of projected images caused by common thermal effects observed in projectors: those caused by the warming-up process and changes in ambient environmental temperature. A software compensation method is also presented. It is suitable for implementation in any existing measurement method that uses raster projectors. The results of performed verification experiments show that the developed compensation method can decrease the thermal drift of the projected images by up to 14 times in the ambient temperature range 14–42 °C.

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Pan, Xiao Ou, Jie Han, Qiang Wang, Ji Song Fu, and Jian Nan Liu. "The Research for the 3D Morphology Measurement of Large-Scale Object by Using Digital Projection Speckle Correlation Method (DPSCM)." Advanced Materials Research 721 (July 2013): 579–82. http://dx.doi.org/10.4028/www.scientific.net/amr.721.579.

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The Digital Projection Speckle Correlation Method (DPSCM) is a non-contact full-field optical 3D profile and deformation measurement technique, which combines with 2D Digital Image Correlation Method (DICM), using LCD projector to produce random speckle that is projected on the surface of the sample.In this paper,the 3D profile and deformation measurement experiment of large-scale objects is finished by DPSCM,and the factor which influences the result of experiment is also discussed

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Ehnes, Jochen, and Michitaka Hirose. "Projected Reality - Content Delivery Right onto Objects of Daily Life." International Journal of Virtual Reality 5, no. 3 (January 1, 2006): 17–23. http://dx.doi.org/10.20870/ijvr.2006.5.3.2694.

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Spatial augmented reality using controllable projector-camera-systems to project onto objects directly, or Projected Reality as we call it, offers the possibility to augment objects without requiring their users to wear or carry any devices. In order to provide the freedom of movement to users, we developed an architecture that allows projected applications to roam a network of projection units to follow the users. The concept of connecting physical objects with content in form of projected applications, although devised for projection based augmented reality systems, can be applied to HMD based or hand held AR systems as well. After a description of our AR projection system and a example application that could be used to provide location specific information to travelers using public transportation systems, we will lay out our vision of a system that may be able to provide content on a global scale

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Kalisperakis, Ilias, Lazaros Grammatikopoulos, Elli Petsa, and George Karras. "A Structured-Light Approach for the Reconstruction of Complex Objects." Geoinformatics FCE CTU 6 (December 21, 2011): 259–66. http://dx.doi.org/10.14311/gi.6.32.

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Recently, one of the central issues in the fields of Photogrammetry, Computer Vision, Computer Graphics and Image Processing is the development of tools for the automatic reconstruction of complex 3D objects. Among various approaches, one of the most promising is Structured Light 3D scanning (SL) which combines automation and high accuracy with low cost, given the steady decrease in price of cameras and projectors. SL relies on the projection of different light patterns, by means of a video projector, on 3D object sur faces, which are recorded by one or more digital cameras. Automatic pattern identification on images allows reconstructing the shape of recorded 3D objects via triangulation of the optical rays corresponding to projector and camera pixels. Models draped with realistic phototexture may be thus also generated, reproducing both geometry and appearance of the 3D world. In this context, subject of our research is a synthesis of state-of-the-art as well as the development of novel algorithms, in order to implement a 3D scanning system consisting, at this stage, of one consumer digital camera (DSLR) and a video projector. In the following, the main principles of structured light scanning and the algorithms implemented in our system are presented, and results are given to demonstrate the potential of such a system. Since this work is part of an ongoing research project, future tasks are also discussed.

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Hidaka, Hironori, Yusuke Monno, and Masatoshi Okutomi. "Spectral Reflectance Estimation Using Projector with Unknown Spectral Power Distribution." Color and Imaging Conference 2020, no. 28 (November 4, 2020): 205–9. http://dx.doi.org/10.2352/issn.2169-2629.2020.28.32.

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A lighting-based multispectral imaging system using an RGB camera and a projector is one of the most practical and low-cost systems to acquire multispectral observations for estimating the scene's spectral reflectance information. However, existing projector-based systems assume that the spectral power distribution (SPD) of each projector primary is known, which requires additional equipment such as a spectrometer to measure the SPD. In this paper, we present a method for jointly estimating the spectral reflectance and the SPD of each projector primary. In addition to adopting a common spectral reflectance basis model, we model the projector's SPD by a low-dimensional model using basis functions obtained by a newly collected projector's SPD database. Then, the spectral reflectances and the projector's SPDs are alternatively estimated based on the basis models. We experimentally show the performance of our joint estimation using a different number of projected illuminations and investigate the potential of the spectral reflectance estimation using a projector with unknown SPD.

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Stark, John, Craig Foster, and Charles Yu. "Axisymmetric Thermal Finite Element Analysis of Effects of Intraocular Projector in the Human Eye." American Journal of Undergraduate Research 17, no. 4 (March 31, 2021): 49–57. http://dx.doi.org/10.33697/ajur.2020.035.

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Millions of people worldwide live with corneal opacity which continues to be one of the leading causes of blindness. Corneal opacity is treatable. However, the surgical methods for treating this condition, such as corneal transplantation and keratoprosthesis, have many complications. The use of an intraocular projector is a promising approach to treat corneal blindness. Like any device using electrical power, an intraocular projection device produces heat, which could potentially damage eye tissue. Australian and international standards state that there cannot be an increase of temperature of 2 °C caused by an implanted device. In order to determine if these standards are met, a 2D axisymmetric thermal analysis of the projector in the human eye is conducted in ANSYS Workbench. With the projector operating at its maximum wattage, our analysis shows that an air gap extension within the projector will help maintain the temperature increase below 2 °C. KEYWORDS: Finite Element Analysis; Eye; Heat Dissipation; Axisymmetric; Thermal Conductivity; Internal Heat Generation; Corneal Blindness; ANSYS; Intraocular Projector

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Wang, Shiquan. "Far-Field Performances Prediction of High Frequency Projectors Using Secondary Source Array Method." Journal of Computational Acoustics 25, no. 02 (November 2, 2016): 1750002. http://dx.doi.org/10.1142/s0218396x17500023.

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This paper investigates the prediction of the far-field performances of high frequency projectors using the second source array method (SSAM). The far-field parameters can be calculated accurately using the complex acoustic pressure data of two very close parallel planes which lie in the near-field region of the projector. The paper simulates the feasibility of predicting the far-field parameters such as transmitting voltage response and the far-field directivity pattern. The predicting results are compared with that calculated using boundary element method (BEM). It shows very good agreement between the two methods. A planar high frequency projector is measured using the near-field method. In order to verify the predicting results, the far-field measurement is performed for the same projector. The comparison of the results shows that the near-field method is capable to precisely predict the far-field parameters of the projector.

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Patil, Harshal Ashok, Shrikant S. Chitko, Veerendra V. Kerudi, Neeraj S. Patil, Amit Maheshwari, and Ruchika Singh. "Custom made profile projector: A new, innovative, and economical way to evaluation of tooth enamel loss after acid etching: An in vitro study." APOS Trends in Orthodontics 6 (March 4, 2016): 95–98. http://dx.doi.org/10.4103/2321-1407.177964.

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Introduction Aim of this in vitro study is to evaluate the loss of tooth enamel after acid etching using a custom made profile projector (×100). Materials and Methods Twenty human extracted maxillary and mandibular premolars were collected, and each tooth was mounted on an acrylic block (2 cm × 1 cm) along with a 0.8 mm stainless steel wire partially embedded in acrylic in front of the buccal surface of the teeth. The 0.8 mm wire was used for reference; the image appeared on the projection screen was 80 mm implying that magnification ×100 has been achieved. Fabrication of custom made profile projector followed the principles of optics. Two projections of each sample before and after etching were projected. The projection was recorded using tracing paper. The difference between the two tracings before and after etching was measured using a millimeter scale. This reading was converted into microns, i.e., 1 mm = 10 μ. Results The statistical method used for this study is a measure of central tendency. The research shows that the average enamel loss was around 15.25 microns. The median is a value at the midpoint of the group, and median for enamel loss is 15 μ Mode for enamel loss is 15 μ that means most frequent or most repetitive enamel loss is 15 μ. The maximum enamel loss was 25 μ, and minimum of that was 10 μ. Conclusions The results of this study indicate that etching enamel with 37% phosphoric acid for 30 s loses 15 μ of surface enamel using an economical and efficient custom made profile projector.

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Elsharkawy, Ahmed, Khawar Naheem, Dongwoo Koo, and Mun Sang Kim. "A UWB-Driven Self-Actuated Projector Platform for Interactive Augmented Reality Applications." Applied Sciences 11, no. 6 (March 23, 2021): 2871. http://dx.doi.org/10.3390/app11062871.

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With the rapid development of interactive technology, creating systems that allow users to define their interactive envelope freely and provide multi-interactive modalities is important to build up an intuitive interactive space. We present an indoor interactive system where a human can customize and interact through a projected screen utilizing the surrounding surfaces. An ultra-wideband (UWB) wireless sensor network was used to assist human-centered interaction design and navigate the self-actuated projector platform. We developed a UWB-based calibration algorithm to facilitate the interaction with the customized projected screens, where a hand-held input device was designed to perform mid-air interactive functions. Sixteen participants were recruited to evaluate the system performance. A prototype level implementation was tested inside a simulated museum environment, where a self-actuated projector provides interactive explanatory content for the on-display artifacts under the user’s command. Our results depict the applicability to designate the interactive screen efficiently indoors and interact with the augmented content with reasonable accuracy and relatively low workload. Our findings also provide valuable user experience information regarding the design of mobile and projection-based augmented reality systems, with the ability to overcome the limitations of other conventional techniques.

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Siriborvornratanakul, Thitirat. "Enhancing User Experiences of Mobile-Based Augmented Reality via Spatial Augmented Reality: Designs and Architectures of Projector-Camera Devices." Advances in Multimedia 2018 (April 18, 2018): 1–17. http://dx.doi.org/10.1155/2018/8194726.

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As smartphones, tablet computers, and other mobile devices have continued to dominate our digital world ecosystem, there are many industries using mobile or wearable devices to perform Augmented Reality (AR) functions in their workplaces in order to increase productivity and decrease unnecessary workloads. Mobile-based AR can basically be divided into three main types: phone-based AR, wearable AR, and projector-based AR. Among these, projector-based AR or Spatial Augmented Reality (SAR) is the most immature and least recognized type of AR for end users. This is because there are a small number of commercial products providing projector-based AR functionalities in a mobile manner. Also, prices of mobile projectors are still relatively high. Moreover, there are still many technical problems regarding projector-based AR that have been left unsolved. Nevertheless, it is projector-based AR that has potential to solve a fundamental problem shared by most mobile-based AR systems. Also the always-visible nature of projector-based AR is one good answer for solving current user experience issues of phone-based AR and wearable AR systems. Hence, in this paper, we analyze what are the user experience issues and technical issues regarding common mobile-based AR systems, recently widespread phone-based AR systems, and rising wearable AR systems. Then for each issue, we propose and explain a new solution of how using projector-based AR can solve the problems and/or help enhance its user experiences. Our proposed framework includes hardware designs and architectures as well as a software computing paradigm towards mobile projector-based AR systems. The proposed design is evaluated by three experts using qualitative and semiquantitative research approaches.

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Rajmic, Pavel, Pavel Záviška, Vítězslav Veselý, and Ondřej Mokrý. "A New Generalized Projection and Its Application to Acceleration of Audio Declipping." Axioms 8, no. 3 (September 19, 2019): 105. http://dx.doi.org/10.3390/axioms8030105.

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In convex optimization, it is often inevitable to work with projectors onto convex sets composed with a linear operator. Such a need arises from both the theory and applications, with signal processing being a prominent and broad field where convex optimization has been used recently. In this article, a novel projector is presented, which generalizes previous results in that it admits to work with a broader family of linear transforms when compared with the state of the art but, on the other hand, it is limited to box-type convex sets in the transformed domain. The new projector is described by an explicit formula, which makes it simple to implement and requires a low computational cost. The projector is interpreted within the framework of the so-called proximal splitting theory. The convenience of the new projector is demonstrated on an example from signal processing, where it was possible to speed up the convergence of a signal declipping algorithm by a factor of more than two.

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Li, Wen Guo, and Shao Jun Duan. "Convenient Calibration Procedure for Structured Light Projection System." Advanced Materials Research 662 (February 2013): 777–80. http://dx.doi.org/10.4028/www.scientific.net/amr.662.777.

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We present a convenient calibration method for structured light projection system. The proposed clibration approach can realize 3D shape measurement without projector calibration, without system calibration, without precise linear z stage to be used, the relative position between camera and projector can be arbitrary, and the only involved device is a plane board. Experiment results validated that the accuracy of the proposed approach.

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Fernández-Rodicio, Enrique, Víctor González-Pacheco, José Carlos Castillo, Álvaro Castro-González, María Malfaz, and Miguel A. Salichs. "Projection Surfaces Detection and Image Correction for Mobile Robots in HRI." Journal of Sensors 2017 (2017): 1–16. http://dx.doi.org/10.1155/2017/4853915.

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Projectors have become a widespread tool to share information in Human-Robot Interaction with large groups of people in a comfortable way. Finding a suitable vertical surface becomes a problem when the projector changes positions when a mobile robot is looking for suitable surfaces to project. Two problems must be addressed to achieve a correct undistorted image: (i) finding the biggest suitable surface free from obstacles and (ii) adapting the output image to correct the distortion due to the angle between the robot and a nonorthogonal surface. We propose a RANSAC-based method that detects a vertical plane inside a point cloud. Then, inside this plane, we apply a rectangle-fitting algorithm over the region in which the projector can work. Finally, the algorithm checks the surface looking for imperfections and occlusions and transforms the original image using a homography matrix to display it over the area detected. The proposed solution can detect projection areas in real-time using a single Kinect camera, which makes it suitable for applications where a robot interacts with other people in unknown environments. Our Projection Surfaces Detector and the Image Correction module allow a mobile robot to find the right surface and display images without deformation, improving its ability to interact with people.

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Hayakawa, Hiroki, and Tomohiro Yendo. "Projection type 3D display using spinning screen." Electronic Imaging 2020, no. 2 (January 26, 2020): 99–1. http://dx.doi.org/10.2352/issn.2470-1173.2020.2.sda-099.

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We propose 3D display that scans light rays from projector and enables stereoscopic display by arranging a number of long and thin mirror scanners with a gap and spinning each mirror scanner. This proposal aims at large-screen 3D display that allows multiple people to observe simultaneously with the naked eye. In previous study, multi-projection type 3D display was proposed as largescreen 3D display. However, many projectors make installation and adjustment complicated. Therefore, we have proposed 3D display that can display large screen with single projector in the past. However, there is a problem that the screen vibrates due to the screen swing mechanism, the scanning speed cannot be increased, and the displayed image appears to flicker. Our new proposed method can reduce the screen vibration by the spin mechanism, increase the scanning speed, and prevent the displayed image from flickering. Computer simulation was performed to confirm the principle of the proposed method, and it was confirmed that appropriate parallax could be presented. The necessary conditions and problems when manufacturing the actual machine were considered, and the prototype was designed.

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Zhao, Shuaihe, Mengyi Zhao, and Shuling Dai. "Automatic Registration of Multi-Projector Based on Coded Structured Light." Symmetry 11, no. 11 (November 12, 2019): 1397. http://dx.doi.org/10.3390/sym11111397.

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Multi-projector display systems are widely used in virtual reality, flight simulators, and other entertainment systems. Geometric distortion and color inconsistency are two key problems to be solved. In this paper a geometric correction principle is theoretically demonstrated and a consistency principle of geometric correction is first proposed. A new method of automatic registration of a multi-projector on a curved screen is put forward. Two pairs of binocular-cameras are used to reconstruct the curved screen. To capture feature points of the curved screen precisely, a group of red-blue coded structured light images is designed to be projected onto the screen. Geometric homography between each projector and the curved screen is calculated to gain a pre-warp template. Work which can gain a seamless display is illustrated by a six-projector system on the curved screen.

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LANDI, GIOVANNI. "DECONSTRUCTING MONOPOLES AND INSTANTONS." Reviews in Mathematical Physics 12, no. 10 (October 2000): 1367–90. http://dx.doi.org/10.1142/s0129055x00000514.

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We give a unifying description of the Dirac monopole on the 2-sphere S2, of a graded monopole on a (2, 2)-supersphere S2, 2 and of the BPST instanton on the 4-sphere S4, by constructing a suitable global projector p via equivariant maps. This projector determines the projective modules of finite type of sections of the corresponding vector bundle. The canonical connection ∇ = p ◦ d is used to compute the topological charge which is found to be equal to -1 for the three cases. The transposed projector q = pt gives the value +1 for the charges; this showing that transposition of projectors, although an isomorphism in K-theory, is not the identity map. We also study the invariance under the action of suitable Lie groups.

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Yang, Shourui, Miao Liu, Jiahui Song, Shibin Yin, Yongjie Ren, Jigui Zhu, and Shengyong Chen. "Projector distortion residual compensation in fringe projection system." Optics and Lasers in Engineering 114 (March 2019): 104–10. http://dx.doi.org/10.1016/j.optlaseng.2018.10.015.

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Ahmed, Bilal, Jong Hun Lee, Yong Yi Lee, and Kwan H. Lee. "Projector primary-based optimization for superimposed projection mappings." Journal of Electronic Imaging 27, no. 01 (February 21, 2018): 1. http://dx.doi.org/10.1117/1.jei.27.1.011011.

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Beavers, Roy. "Petrographic Slides Projected in a 35mm Slide Projector." Microscopy Today 11, no. 2 (April 2003): 46. http://dx.doi.org/10.1017/s1551929500052524.

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Kuwata, Muneharu, Tomohiro Sasagawa, Kuniko Kojima, Junichi Aizawa, Akihisa Miyata, Shinsuke Shikama, and Hiroaki Sugiura. "Projection optical system for a compact rear projector." Journal of the Society for Information Display 14, no. 2 (2006): 199. http://dx.doi.org/10.1889/1.2176140.

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Yang, Yucheol, and Sung-Wook Min. "Projection-Type Integral Imaging Using a Pico-projector." Journal of the Optical Society of Korea 18, no. 6 (December 25, 2014): 714–19. http://dx.doi.org/10.3807/josk.2014.18.6.714.

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Kitajima, Yuki, Daisuke Iwai, and Kosuke Sato. "Simultaneous Projection and Positioning of Laser Projector Pixels." IEEE Transactions on Visualization and Computer Graphics 23, no. 11 (November 2017): 2419–29. http://dx.doi.org/10.1109/tvcg.2017.2734478.

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Xu, Long, Yaping Cao, Yongtao Yu, Jian Wang, and Liping Zhou. "Projector undistortion for high-accuracy fringe projection profilometry." Measurement Science and Technology 32, no. 10 (June 25, 2021): 105009. http://dx.doi.org/10.1088/1361-6501/ac0373.

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Yu, Changzhi, Fang Ji, Junpeng Xue, and Yajun Wang. "Adaptive Binocular Fringe Dynamic Projection Method for High Dynamic Range Measurement." Sensors 19, no. 18 (September 18, 2019): 4023. http://dx.doi.org/10.3390/s19184023.

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Three-dimensional measurement with fringe projection sensor has been commonly researched. However, the measurement accuracy and efficiency of most fringe projection sensors are still seriously affected by image saturation and the non-linear effects of the projector. In order to solve the challenge, in conjunction with the advantages of stereo vision technology and fringe projection technology, an adaptive binocular fringe dynamic projection method is proposed. The proposed method can avoid image saturation by adaptively adjusting the projection intensity. Firstly, the flowchart of the proposed method is explained. Then, an adaptive optimal projection intensity method based on multi-threshold segmentation is introduced to adjust the projection illumination. Finally, the mapping relationship of binocular saturation point and projection point is established by binocular transformation and left camera–projector mapping. Experiments demonstrate that the proposed method can achieve higher accuracy for high dynamic range measurement.

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Journal articles on the topic 'Projector'

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