The realistic rendering of scenes defined by the cloud of points

Occlusion Culling for Wide-Angle Computer-Generated Holograms Using Phase Added Stereogram Technique

Photonics ◽

10.3390/photonics8080298 ◽

2021 ◽

Vol 8 (8) ◽

pp. 298

Author(s):

Juan Martinez-Carranza ◽

Tomasz Kozacki ◽

Rafał Kukołowicz ◽

Maksymilian Chlipala ◽

Moncy Sajeev Idicula

Keyword(s):

Point Sources ◽

Wide Angle ◽

Computer Generated Holograms ◽

Propagation Methods ◽

Propagation Technique ◽

3D Scene ◽

Occlusion Culling ◽

Fourier Type ◽

Cloud Of Points

A computer-generated hologram (CGH) allows synthetizing view of 3D scene of real or virtual objects. Additionally, CGH with wide-angle view offers the possibility of having a 3D experience for large objects. An important feature to consider in the calculation of CGHs is occlusion between surfaces because it provides correct perception of encoded 3D scenes. Although there is a vast family of occlusion culling algorithms, none of these, at the best of our knowledge, consider occlusion when calculating CGHs with wide-angle view. For that reason, in this work we propose an occlusion culling algorithm for wide-angle CGHs that uses the Fourier-type phase added stereogram (PAS). It is shown that segmentation properties of the PAS can be used for setting efficient conditions for occlusion culling of hidden areas. The method is efficient because it enables processing of dense cloud of points. The investigated case has 24 million of point sources. Moreover, quality of the occluded wide-angle CGHs is tested by two propagation methods. The first propagation technique quantifies quality of point reproduction of calculated CGH, while the second method enables the quality assessment of the occlusion culling operation over an object of complex shape. Finally, the applicability of proposed occlusion PAS algorithm is tested by synthetizing wide-angle CGHs that are numerically and optically reconstructed.

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Adaptive spiral tool path generation for computer numerical control machining using point cloud

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406221990077 ◽

2021 ◽

pp. 095440622199007

Author(s):

Mandeep Dhanda ◽

Aman Kukreja ◽

SS Pande

Keyword(s):

Tool Path ◽

Cnc Machining ◽

Numerical Control ◽

Numerical Control Machining ◽

Form Errors ◽

Spiral Tool Path ◽

Novel Method ◽

Mesh Grid ◽

Cloud Of Points ◽

Cam Software

This paper reports a novel method to generate adaptive spiral tool path for the CNC machining of complex sculptured surface represented in the form of cloud of points without the need for surface fitting. The algorithm initially uses uniform 2 D circular mesh-grid to compute the cutter location (CL) points by applying the tool inverse offset method (IOM). These CL points are refined adaptively till the surface form errors converge below the prescribed tolerance limits in both circumferential and radial directions. They are further refined to eliminate the redundancy in machining and generate optimum region wise tool path to minimize the tool lifts. The NC part programs generated by our algorithm were widely tested for different case studies using the commercial CNC simulator as well as by the actual machining trial. Finally, a comparative study was done between our developed system and the commercial CAM software. The results showed that our system is more efficient and robust in terms of the obtained surface quality, productivity, and memory requirement.

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Visualization of the Strain-Rate State of a Data Cloud: Analysis of the Temporal Change of an Urban Multivariate Description

Applied Sciences ◽

10.3390/app9142920 ◽

2019 ◽

Vol 9 (14) ◽

pp. 2920

Author(s):

Lorena Salazar-Llano ◽

Camilo Bayona-Roa

Keyword(s):

Strain Rate ◽

Temporal Change ◽

Three Dimensional ◽

Urban System ◽

Deformation Pattern ◽

Analysis Methodology ◽

Global Deformation ◽

Temporal Rate ◽

Cloud Of Points ◽

Entire Dataset

One challenging problem is the representation of three-dimensional datasets that vary with time. These datasets can be thought of as a cloud of points that gradually deforms. However, point-wise variations lack information about the overall deformation pattern, and, more importantly, about the extreme deformation locations inside the cloud. This present article applies a technique in computational mechanics to derive the strain-rate state of a time-dependent and three-dimensional data distribution, by which one can characterize its main trends of shift. Indeed, the tensorial analysis methodology is able to determine the global deformation rates in the entire dataset. With the use of this technique, one can characterize the significant fluctuations in a reduced multivariate description of an urban system and identify the possible causes of those changes: calculating the strain-rate state of a PCA-based multivariate description of an urban system, we are able to describe the clustering and divergence patterns between the districts of a city and to characterize the temporal rate in which those variations happen.

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Hand Pose Understanding with Large-Scale Photo-Realistic Rendering Dataset

IEEE Transactions on Image Processing ◽

10.1109/tip.2021.3070439 ◽

2021 ◽

pp. 1-1

Author(s):

Xiaoming Deng ◽

Yinda Zhang ◽

Jian Shi ◽

Yuying Zhu ◽

Dachuan Cheng ◽

...

Keyword(s):

Large Scale ◽

Realistic Rendering ◽

Hand Pose

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Accuracy Analysis of Fringe Projection Systems Based on Blue Light Technology

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.615.9 ◽

2014 ◽

Vol 615 ◽

pp. 9-14 ◽

Cited By ~ 3

Author(s):

Claudio Bernal ◽

Beatriz de Agustina ◽

Marta María Marín ◽

Ana Maria Camacho

Keyword(s):

Blue Light ◽

Point Clouds ◽

Fringe Projection ◽

Accuracy Analysis ◽

Scanning Procedure ◽

Structured Light Scanner ◽

Cloud Of Points ◽

3D Digitizing

Some manufacturers of 3D digitizing systems are developing and market more accurate, fastest and affordable systems of fringe projection based on blue light technology. The aim of the present work is the determination of the quality and accuracy of the data provided by the LED structured light scanner Comet L3D (Steinbichler). The quality and accuracy of the cloud of points produced by the scanner is determined by measuring a number of gauge blocks of different sizes. The accuracy range of the scanner has been established through multiple digitizations showing the dependence on different factors such as the characteristics of the object and scanning procedure. Although many factors influence, accuracies announced by manufacturer have been achieved under optimal conditions and it has been noted that the quality of the point clouds (density, noise, dispersion of points) provided by this system is higher than that obtained with laser technology devices.

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