scholarly journals Use of Gradient-Based Shadow Detection for Estimating Environmental Illumination Distribution

2018 ◽  
Vol 8 (11) ◽  
pp. 2255 ◽  
Author(s):  
Sangyoon Lee ◽  
Hyunki Hong
Keyword(s):  
Three Dimensional ◽  
Local Features ◽  
Shadow Detection ◽  
Reference Object ◽  
Light Sources ◽  
Illumination Estimation ◽  
Shadow Boundary ◽  
Sampling Position ◽  
Gradient Based ◽  
Edge Based

Environmental illumination information is necessary to achieve a consistent integration of virtual objects in a given image. In this paper, we present a gradient-based shadow detection method for estimating the environmental illumination distribution of a given scene, in which a three-dimensional (3-D) augmented reality (AR) marker, a cubic reference object of a known size, is employed. The geometric elements (the corners and sides) of the AR marker constitute the candidate’s shadow boundary; they are obtained on a flat surface according to the relationship between the camera and the candidate’s light sources. We can then extract the shadow regions by collecting the local features that support the candidate’s shadow boundary in the image. To further verify the shadows passed by the local features-based matching, we examine whether significant brightness changes occurred in the intersection region between the shadows. Our proposed method can reduce the unwanted effects caused by the threshold values during edge-based shadow detection, as well as those caused by the sampling position during point-based illumination estimation.

An Efficient Multiple Description Coding for Multi-View Video Based on the Correlation of Spatial Polyphase Transformed Subsequences

2019 ◽  
Vol 63 (5) ◽  
pp. 50401-1-50401-7 ◽  
Author(s):  
Jing Chen ◽  
Jie Liao ◽  
Huanqiang Zeng ◽  
Canhui Cai ◽  
Kai-Kuang Ma
Keyword(s):  
Video Transmission ◽  
Video Sequence ◽  
Three Dimensional ◽  
The Other ◽  
Multiple Description Coding ◽  
Multiple Description ◽  
Prediction Mode ◽  
Gradient Based ◽  
Directional Interpolation ◽  
Description Coding

Abstract For a robust three-dimensional video transmission through error prone channels, an efficient multiple description coding for multi-view video based on the correlation of spatial polyphase transformed subsequences (CSPT_MDC_MVC) is proposed in this article. The input multi-view video sequence is first separated into four subsequences by spatial polyphase transform and then grouped into two descriptions. With the correlation of macroblocks in corresponding subsequence positions, these subsequences should not be coded in completely the same way. In each description, one subsequence is directly coded by the Joint Multi-view Video Coding (JMVC) encoder and the other subsequence is classified into four sets. According to the classification, the indirectly coding subsequence selectively employed the prediction mode and the prediction vector of the counter directly coding subsequence, which reduces the bitrate consumption and the coding complexity of multiple description coding for multi-view video. On the decoder side, the gradient-based directional interpolation is employed to improve the side reconstructed quality. The effectiveness and robustness of the proposed algorithm is verified by experiments in the JMVC coding platform.

Development of a three-dimensional color rendition space for tunable solid-state light sources

2021 ◽  
Vol 2021 (29) ◽  
pp. 136-140
Author(s):  
Dorukalp Durmus
Keyword(s):  
Solid State ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Color Discrimination ◽  
Continuous Measure ◽  
Light Sources ◽  
Vast Number ◽  
Lighting Systems ◽  
Single Number

The quality of building electric lighting systems can be assessed using color rendition metrics. However, color rendition metrics are limited in quantifying tunable solid-state light sources, since tunable lighting systems can generate a vast number of different white light spectra, providing flexibility in terms of color quality and energy efficiency. Previous research suggests that color rendition is multi-dimensional in nature, and it cannot be simplified to a single number. Color shifts under a test light source in comparison to a reference illuminant, changes in color gamut, and color discrimination are important dimensions of the quality of electric light sources, which are not captured by a single-numbered metric. To address the challenges in color rendition characterization of modern solid-state light sources, the development of a multi-dimensional color rendition space is proposed. The proposed continuous measure can quantify the change in color rendition ability of tunable solid-state light devices with caveats. Future work, discretization of the continuous color rendition space, will be carried out to address the shortcomings of a continuous three-dimensional space.

A High Fidelity Quality Assessment of High Pressure Turbine Blades Using Surface Curvature and Gradient-Based Adjoint

2018 ◽  
Author(s):  
Akhil Mulloth ◽  
Gabriel Banks ◽  
Giulio Zamboni ◽  
Simon Bather
Keyword(s):  
Quality Assessment ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Surface Curvature ◽  
Assessment Process ◽  
Screening Process ◽  
Profile Tolerance ◽  
Gradient Based ◽  
Parts Manufacturing ◽  
The Impact

Gas turbine performance is highly dependent on the quality of the manufactured parts. Manufacturing variations in the parts can significantly alter the performance, especially efficiency and thus SFC. The legacy process is to accept variations within predefined profile tolerance limits and a few other qualitative parameters, mostly at a few, key two-dimensional aerofoil sections. With the widespread use of White light scans and other similar three-dimensional scans, this has improved to include the three-dimensional profile. The future however may lie with performance based quality assessment of manufactured parts, combined with quantitative surface quality assessment to implement an intelligent screening process for the parts. The adjoint method, typically used for shape optimization is adapted to provide a prediction of the impact on performance due to manufacturing variations. The work presented outlines a three stage quality assessment process for manufactured parts, involving three-dimensional profile tolerance based screening, followed by a surface curvature based screening and finally an Adjoint based performance prediction.

scholarly journals Ultrafast nonlocal collective dynamics of Kane plasmon-polaritons in a narrow-gap semiconductor

2019 ◽  
Vol 5 (8) ◽  
pp. eaau9956 ◽  
Author(s):  
A. Charnukha ◽  
A. Sternbach ◽  
H. T. Stinson ◽  
R. Schlereth ◽  
C. Brüne ◽  
...  
Keyword(s):  
Fiber Optics ◽  
Near Field ◽  
Three Dimensional ◽  
Large Momentum ◽  
Light Sources ◽  
New States ◽  
High Bandwidth ◽  
And Control ◽  
2D And 3D ◽  
Plasmon Polaritons

The observation of ultrarelativistic fermions in condensed-matter systems has uncovered a cornucopia of novel phenomenology as well as a potential for effective ultrafast light engineering of new states of matter. While the nonequilibrium properties of two- and three-dimensional (2D and 3D) hexagonal crystals have been studied extensively, our understanding of the photoinduced dynamics in 3D single-valley ultrarelativistic materials is, unexpectedly, lacking. Here, we use ultrafast scanning near-field optical spectroscopy to access and control nonequilibrium large-momentum plasmon-polaritons in thin films of a prototypical narrow-bandgap semiconductor Hg0.81Cd0.19Te. We demonstrate that these collective excitations exhibit distinctly nonclassical scaling with electron density characteristic of the ultrarelativistic Kane regime and experience ultrafast initial relaxation followed by a long-lived highly coherent state. Our observation and ultrafast control of Kane plasmon-polaritons in a semiconducting material using light sources in the standard telecommunications fiber-optics window open a new avenue toward high-bandwidth coherent information processing in next-generation plasmonic circuits.

scholarly journals Micro-System Displacement and Profile Measurement By an Integrated Photon Tunneling and Confocal Microscope

2002 ◽  
Vol 18 (4) ◽  
pp. 173-183
Author(s):  
Wen-Jong Chen ◽  
Chih-Kung Lee ◽  
Shui-Shong Lu ◽  
Long-Sun Huang ◽  
Ta-Shun Chu ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Electrostatic Force ◽  
Three Dimensional ◽  
Confocal Laser Scanning Microscope ◽  
Confocal Laser ◽  
Profile Measurement ◽  
Light Sources ◽  
Halogen Lamp ◽  
Photon Tunneling ◽  
Micro Systems

ABSTRACTAn integrated optical method for measuring deformation of micro-mechanical systems with better than sub-micron resolutions is detailed. Both a confocal laser scanning microscope and a photon tunneling microscope were integrated into a single microscopy system due to their complimentary capabilities for examining sub-micrometer deformations. A halogen lamp and laser were adopted as the two light sources for the measurements. Since topographic information of samples up to a 15μm by 15μm area can be measured, a three-dimensional displacement field of the sample was extracted by comparing topographies of the same specimen area before and after deformation. The bending and twisting deformation of a micro-mirror driven by the electrostatic force was measured to demonstrate the capability of this newly developed instrument. The experimental data obtained agrees reasonably well with the theoretical results calculated by adopting an analytical solution and a finite element method. The small discrepancy in the result can be traced to the surface roughness effect, which is often non-negligible in micro-systems.

Sign in / Sign up

Export Citation Format

Share Document