Phase-height mapping algorithm is the key technology of phase measurement profilometry (PMP). Because of lens distortion of the projector, phase-height mapping is not simple linear transform and the mapping procedure become complex. A method is introduced to simplify phase-height mapping. The detail of this method is expressed as following: (1) Two suits of sinusoidal gratings which are perpendicular to each other are projected to the calibration target respectively. (2) The position of each target mark in calibration target is estimated using standard image processing technique. (3) Distortion coefficients of projector are estimated from the phase of target marks and their positions, according to the camera model. (4) Ideal phase distribution for projecting is designed. (5) According to the camera distortion model, distorting and transforming the ideal phase distribution, distorted phase distribution in the image plane is acquired. Then the phase-shifting sinusoidal fringes with distorted phase are generated. The anamorphic sinusoidal fringes are distorted inversely during projecting because projecting process is the reverse process of imaging. Therefore, the ideal sinusoidal fringes are projected. The phase-height mapping of PMP system can be ideally expressed and the mapping procedure is simplified. A practical PMP measurement system was constructed and the distortion coefficients are estimated by calibrating the system. They are k1=-6.989×10-2 and p1=5.957×10-3. Then the distorted sinusoidal fringes are generated and projected for calibrating. Distortion coefficients are estimated again. They are k1=-7.882×10-3 and p1=-3.777×10-3. It is found from the experimental results that the distortion of projector is reduced a lot after grating correction.
360-degree video is increasingly used to create immersive user experiences; however, it is typically limited to a single user and not interactive. Recent studies have explored the potential of 360 video to support multi-user collaboration in remote settings. These studies identified several challenges with respect to 360 live streams, such as the lack of gaze awareness, out-of-sync views, and missed gestures. To address these challenges, we created 360Anywhere, a framework for 360 video-based multi-user collaboration that, in addition to allowing collaborators to view and annotate a 360 live stream, also supports projection of annotations in the 360 stream back into the real-world environment in real-time. This enables a range of collaborative augmented reality applications not supported with existing tools. We present the 360Anywhere framework and tools that allow users to generate applications tailored to specific collaboration and augmentation needs with support for remote collaboration. In a series of exploratory design sessions with users, we assess 360Anywhere's power and flexibility for three mobile ad-hoc scenarios. Using 360Anywhere, participants were able to set up and use fairly complex remote collaboration systems involving projective augmented reality in less than 10 minutes.
The aerodynamic characteristics of two-dimensional arched thinwing flexible sail,which sail-wing shape changes as the wind force and wind direction,are hard to analyse.Based on vortex distribution panel method theory,authors sum up the experience of predecessors,advance a improved simulation method to analyse the aerodynamic characteristics of two-dimensional arched thinwing flexible sail under low angles of attack in uncompressible ideal fluid and programe the method.Compared with the experimental results,it is found that the calculated results of this method is acceptable.The research results will be helpful in the further study of the numerical simulation and academic analyse.
Based on summary of the industry standard requirements of the supporting structure on anchoring and mooring equipments,the supporting structure is designed in terms of The Rules and Regulations for the Classification of Sea-going Steel Ships,and the strength of the supporting structure is analyzed by FEM in Patran / Nastran.The numerical results show that the strength of the designed structure satisfies the CCS relevant requirements.
Based on Goodman model,which is used for simulating the contact condition between beams,using Winkler foundation model upgraded as an elastic supporting body with horizontal and vertical forces,a set of differential equations and relevant theoretical solutions for bi-layer beams on the elastic foundation with the horizontal frictional resistance are obtained.Considering the vertical tension and compression and the horizontal shear of beams,a concept of the generalized reaction modulus for interlayer foundation isproposed and the corresponding formulas are obtained.The influence of the horizontal frictional resistance on the deflection,the total sectional moment and the maximum flexural stress of bi-layer beams is discussed.The results show that the influence of the horizontal frictional resistance can not be ignored.
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