- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Real-time detection of moving cast shadows using foreground luminance statistics
摘要： This paper presents a robust real-time method for detection of moving cast shadows which employs the assumption of higher interdependence of luminance values for the shadow pixels in larger regions compared to the object pixels. First, a fast modified image differencing technique is used to separate foreground pixels from the background. Next, for a moving window of fixed width scanning the foreground regions, a new measure called Modified Correlation is introduced. The new measure is determined by first computing the correlation between the luminance values of the moving window and luminance values of its neighbouring windows; this correlation is then divided by a robust-to-noise range measured based on the luminance values of the moving window. The modified correlation exhibits abrupt rising transitions as it enters the shadow region from the object region, transitions which can be used to separate object pixels from shadow pixels. Thus, the new method is very effective at suppressing moving cast shadows, while avoiding limiting structures, unrealistic assumptions, the need for a-priori knowledge, and manual selection of critical parameters. An average shadow detection rate of 85.4% and an average shadow discrimination rate of 99.5% over multiple different sequences, higher than those of available methods in the literature, confirm the efficacy of the method. The robustness of the method is examined under different lighting conditions, different target-environment combinations, and sequences with object-shadow occlusion. The proposed method is computationally efficient and suitable for real-time situations.
关键词： Moving cast shadow,Image difference,Correlation,Sliding window,Foreground mask,Real-time detection
更新于2025-09-23 15:23:52
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New automated method for extracting river information using optimized spectral threshold water index
摘要： The accurate extraction of mountain river information is highly significant in water resource investigation and ecological environment protection. However, there are some problems in the existing methods of river information extraction, which are mainly the interference from shadows and buildings. Such interference leads to erroneous and redundant extraction of river information, which leads to inaccuracy or incompleteness. In this study, a precise extraction method of mountain river information is established using Landsat8 image and digital elevation model. The main steps of the river extraction method are as follows: (1) we propose the optimized spectral threshold water index to extract river information; (2) based on digital elevation model data, we simulate the mountain shadows of the study area to remove interference from them; (3) we establish the buffer zone of the river network using digital elevation model data to solve the problem of redundant extraction of river information; (4) we separately calculate and then standardize land surface temperature, albedo, and normalized different building index. The effects of buildings near the river are removed. Results show a relative accuracy of 97.52%. The new method decreases the interference of mountain shadows and buildings.
关键词： Digital elevation model,Mountain shadow,Building removal,River buffer zone,Landsat8
更新于2025-09-23 15:23:52
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[IEEE 2017 International Renewable and Sustainable Energy Conference (IRSEC) - Tangier (2017.12.4-2017.12.7)] 2017 International Renewable and Sustainable Energy Conference (IRSEC) - Video Solar Plant Monitoring
摘要： In order to ensure efficient monitoring of solar plants, aerial video inspection using drones is unavoidable. The usually encountered problem is the shadow caused by drone on solar panels which may cause a false image interpretation. In this paper, we propose a technique of live shadow detection in video frames based on Otsu thresholding algorithm. To avoid Shaded Frames, the supervisor can automatically detect shaded captured frames of solar panels then acquire frames of the same area from another drone position with corrected angle of view of camera.
关键词： Otsu,shadow,solar plant,solar panel
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE 8th International Conference on Consumer Electronics - Berlin - Berlin, Germany (2018.9.2-2018.9.5)] 2018 IEEE 8th International Conference on Consumer Electronics - Berlin (ICCE-Berlin) - Context-Aware Contrast Enhancement Using Shadow Region Estimation and Bright Channel
摘要： This paper presents a contrast image enhancement method using a shadow region estimation and bright channel. To separate the dark and bright regions, the proposed method estimates the shadow map by selecting the darkest pixels of a low-contrast image. The bright channel represents the brightest pixel among the red, green, and blue pixels and it preserves the bright region of an input image. The resulting image is obtained by synthesizing the input and brightness enhance images using shadow map and bright channel. Experimental results show that the proposed method can provide the enhanced images without undesired artifact brightness saturation and color distortion.
关键词： Contrast enhancement,Shadow estimation,Bright channel prior
更新于2025-09-23 15:22:29
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Multi-Spectral Water Index (MuWI): A Native 10-m Multi-Spectral Water Index for Accurate Water Mapping on Sentinel-2
摘要： Accurate water mapping depends largely on the water index. However, most previously widely-adopted water index methods are developed from 30-m resolution Landsat imagery, with low-albedo commission error (e.g., shadow misclassified as water) and threshold instability being identified as the primary issues. Besides, since the shortwave-infrared (SWIR) spectral band (band 11) on Sentinel-2 is 20 m spatial resolution, current SWIR-included water index methods usually produce water maps at 20 m resolution instead of the highest 10 m resolution of Sentinel-2 bands, which limits the ability of Sentinel-2 to detect surface water at finer scales. This study aims to develop a water index from Sentinel-2 that improves native resolution and accuracy of water mapping at the same time. Support Vector Machine (SVM) is used to exploit the 10-m spectral bands among Sentinel-2 bands of three resolutions (10-m; 20-m; 60-m). The new Multi-Spectral Water Index (MuWI), consisting of the complete version and the revised version (MuWI-C and MuWI-R), is designed as the combination of normalized differences for threshold stability. The proposed method is assessed on coincident Sentinel-2 and sub-meter images covering a variety of water types. When compared to previous water indexes, results show that both versions of MuWI enable to produce native 10-m resolution water maps with higher classification accuracies (p-value < 0.01). Commission and omission errors are also significantly reduced particularly in terms of shadow and sunglint. Consistent accuracy over complex water mapping scenarios is obtained by MuWI due to high threshold stability. Overall, the proposed MuWI method is applicable to accurate water mapping with improved spatial resolution and accuracy, which possibly facilitates water mapping and its related studies and applications on growing Sentinel-2 images.
关键词： MNDWI,OSH,SVM,AWEI,water mapping,water classification,shadow,NDWI,Sentinel-2,MuWI,Landsat,water index,multi-spectral water index,sunglint,machine learning
更新于2025-09-23 15:21:01
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A 3-D Surface Reconstruction with Shadow Processing for Optical Tactile Sensors
摘要： An optical tactile sensor technique with 3-dimension (3-D) surface reconstruction is proposed for robotic fingers. The hardware of the tactile sensor consists of a surface deformation sensing layer, an image sensor and four individually controlled flashing light emitting diodes (LEDs). The image sensor records the deformation images when the robotic finger touches an object. For each object, four deformation images are taken with the LEDs providing different illumination directions. Before the 3-D reconstruction, the look-up tables are built to map the intensity distribution to the image gradient data. The possible image shadow will be detected and amended. Then the 3-D depth distribution of the object surface can be reconstructed from the 2-D gradient obtained using the look-up tables. The architecture of the tactile sensor and the proposed signal processing flow have been presented in details. A prototype tactile sensor has been built. Both the simulation and experimental results have validated the effectiveness of the proposed 3-D surface reconstruction method for the optical tactile sensors. The proposed 3-D surface reconstruction method has the unique feature of image shadow detection and compensation, which differentiates itself from those in the literature.
关键词： shadow detection,3-D reconstruction,robotic finger,tactile sensor,surface reconstruction
更新于2025-09-23 15:21:01
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Process studies on copper laser beam welding over gap by using disc laser at green wavelength
摘要： The increasing demand for the substitution of the internal combustion engine vehicles to the battery electric vehicles requires beside battery cells high performance power electronic devices such as power control units (PCU). However, a combined requirement of high junction temperature stability and a large joint area of the interconnection on the PCU is a challenge for the conventional joining method such as soldering and wire bonding process. The Laser Impulse Metal Bonding (LIMBO) process enables a high temperature stable weld joint and large joint area. During the LIMBO process only minimized thermal stress is induced into the underlying substrate by a spatial separation between both joining partners in an overlap configuration with a gap. Hence, an energetic separation between the melting and joining phase is given. In this paper, the LIMBO process is firstly investigated with the disc laser at wavelength λ = 515 nm. Due to the enhanced absorptivity of the laser beam at this wavelength on copper material, the process duration of the LIMBO process is about the half compared to the LIMBO process with wavelength λ = 1064 nm.
关键词： Shadow projection,Green laser beam,Heat conduction welding mode,Laser beam micro joining,LIMBO
更新于2025-09-23 15:19:57
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Influence of shadow on shunt-type potential-induced degradation for crystalline Si photovoltaic modules exposed outdoors
摘要： Potential-induced degradation (PID) was observed for crystalline Si photovoltaic (PV) modules set at a PID test system constructed outdoors. It was clearly shown that partial shadow and periodical water spray during daytime accelerate PID generation. PID easily occurred just underneath the shielding plate. It was also found that when a large part of one cell in the PV module was shadowed, PID is accelerated; however, when a small part of one cell in the PV module was shadowed or when the weak light is uniformly irradiated, less PID acceleration is observed. Simulation was also carried out for discussing the influence of light irradiation. These findings suggest that UV irradiation during the PID indoor test is essential for the exact estimation of the acceleration factor of the indoor PID test.
关键词： shadow,outdoor test,UV irradiation,potential-induced degradation,crystalline Si photovoltaic modules
更新于2025-09-23 15:19:57
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Carrier-envelope offset frequency stabilization of a thin-disk laser oscillator via depletion modulation
摘要： Unreliability involved in the extraction of shaded vegetation-covered surfaces (VS) is a common problem in urban vegetation mapping. Serving as a solution to it, a novel method named Nonlinear Fitting-based Seeded Region Growing (NFSRG) is explored. With NFSRG, a series of classi?ed results are organized by a seeded-region-growing process. In order to adapt to the variable separability between VS and background, the growing is limited in several weighted buffers de?ned by some nonlinear ?tting relationships. When searching new VS members (member means both pixel and patch) within such a buffer, a gradually reduced weight makes the buffer width continually narrowed as the separability worsens. To avoid unexpected entrances of water and smooth shaded background members, a during-growing constraint, named expansion rate, is proposed. Accuracy assessments reveal that more than 96% of VS members can be accurately extracted by the proposed method.
关键词： shadow,Classi?cation,urban,vegetation,seeded region growing
更新于2025-09-19 17:13:59
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Slow Light using Photorefractive Beam Fanning
摘要： Unreliability involved in the extraction of shaded vegetation-covered surfaces (VS) is a common problem in urban vegetation mapping. Serving as a solution to it, a novel method named Nonlinear Fitting-based Seeded Region Growing (NFSRG) is explored. With NFSRG, a series of classi?ed results are organized by a seeded-region-growing process. In order to adapt to the variable separability between VS and background, the growing is limited in several weighted buffers de?ned by some nonlinear ?tting relationships. When searching new VS members (member means both pixel and patch) within such a buffer, a gradually reduced weight makes the buffer width continually narrowed as the separability worsens. To avoid unexpected entrances of water and smooth shaded background members, a during-growing constraint, named expansion rate, is proposed. Accuracy assessments reveal that more than 96% of VS members can be accurately extracted by the proposed method.
关键词： shadow,Classi?cation,urban,vegetation,seeded region growing
更新于2025-09-19 17:13:59