Yuwei Chen

Yuwei Chen
Finnish Geospatial Research Institute FGI, National Land Survey of Finland · Department of Remote Sensing and Photogrammetry

Ph.D.

About

175
Publications
72,121
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3,253
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Introduction

Publications

Publications (175)
Article
Full-text available
Hyperspectral LiDAR (HSL) has been utilised as an efficacious technique in objects classification and recognition based on its synchronously obtaining spectral and spatial information. However, the spectral information obtained by most of the developed HSL was in the visible and near-infrared range (VNIR, 400–1000 nm). Whereas spectral information...
Article
Full-text available
Pedestrian Dead Reckoning (PDR) is an effective technology for pedestrian navigation. In the PDR, the steps are detected with the measurements of self-contained sensors, i.e., accelerometer, the position is updated with additional heading angles. A smartphone is usually equipped with a low-cost Micro-electromechanical systems (MEMS) accelerometer,...
Article
In a smartphone, the Global Navigation Satellite System (GNSS) receiver is dominant in providing position information for users. However, GNSS signals are vulnerable to the environment, i.e., city canyons and tunnels. Pedestrian dead reckoning (PDR) exploring human walking gaits is another effective method to determine pedestrian position. Accelero...
Article
Full-text available
Nowadays, a chip-scale Global Navigation Satellite System (GNSS) receiver is ubiquitous in smartphones. In a smartphone GNSS receiver, the least square (LS) or Kalman Filter (KF) is implemented to estimate the position. With the aim to improve the smartphone GNSS position accuracy, we propose a position-smoothing method considering more historical...
Article
Nanoimprint technology has the advantages of low cost, high precision, high fidelity and high yield. The metal nanoparticle fluid is non-Newtonian fluid,which is used as the imprint transfer medium to realize high fidelity of pattern because of its the shear thinning effect. In order to functionalize the metal nanoparticles microstructure, the subs...
Article
Position and location constitute critical context for IoT (Internet of Things) devices. Global navigation satellite systems (GNSSs) are the primary apparatus providing precise position and location information for IoT devices in outdoor environments. However, in dense urban areas, non-line-of-sight (NLOS) signals will induce large errors in GNSS ps...
Article
The pipeline, as the fifth largest transportation tool after railway, highway, waterway, and air transportation, has been widely used in industrial production and life. However, in the process of pipeline operations, rapid opening and closing of valves or pump stopping can lead to water hammer. The periodic pressure wave caused by water hammer can...
Article
Full-text available
Hyperdoped silicon (hSi) fabricated via femtosecond laser irradiation has emerged as a promising photoelectric material with strong broadband infrared (IR) absorption. In this work, we measured the optical absorptance of the hSi in the wavelength of 0.3–16.7 µm. Unlike the near to mid wavelength IR absorption, the mid-long wavelength IR (M–LWIR) ab...
Article
Full-text available
Wood-leaf separation aimings to at classifying LiDAR points into wood and leaf components. It is one of the most important genres for improving leaf area index (LAI) estimation and forestry survey accuracy. The wood return signals could artificially increase the apparent foliage content, which needs to be screened out for deriving vital tree attrib...
Poster
Dear Colleagues, Currently, with the popularity of smart devices, assured Position Navigation and Time (PNT) is critical for these devices and some fundamental infrastructures, i.e., power grid. The Global Navigation Satellite System (GNSS) is dominant in providing the PNT information due to its coverage and high accuracy. However, its signals are...
Poster
Dear Colleagues, MEMS technology opens up a new avenue for manufacturing low-cost and small-volume inertial measurement units. Micro inertial sensors are ubiquitous, and can be found in smartphones, cars, and smartwatches. Signals for the micro inertial sensors are sampled and processed for various applications, e.g., health monitoring, vibration...
Article
Full-text available
Digital maps of road networks are a vital part of digital cities and intelligent transportation. In this paper, we provide a comprehensive review on road extraction based on various remote sensing data sources, including high-resolution images, hyperspectral images, synthetic aperture radar images, and light detection and ranging. This review is di...
Preprint
Cluster visualization is an essential task for nonlinear dimensionality reduction as a data analysis tool. It is often believed that Student t-Distributed Stochastic Neighbor Embedding (t-SNE) can show clusters for well clusterable data, with a smaller Kullback-Leibler divergence corresponding to a better quality. There was even theoretical proof f...
Preprint
Neighbor Embedding (NE) that aims to preserve pairwise similarities between data items has been shown to yield an effective principle for data visualization. However, even the currently best NE methods such as Stochastic Neighbor Embedding (SNE) may leave large-scale patterns such as clusters hidden despite of strong signals being present in the da...
Article
Airborne hyperspectral images are used for crop identification with a high classification accuracy because of their high spectral resolution, spatial resolution, and signal-to-noise ratio (SNR). However, the tradeoffs between the three core parameters of a hyperspectral imager (SNR, spatial resolution, and spectral resolution) should be considered...
Article
Full-text available
Dimensionality reduction (DR) is of great significance for simplifying and optimizing hyperspectral image (HSI) features. As a widely used DR method, kernel minimum noise fraction (KMNF) transformation preserves the high-order structures of the original data perfectly. However, the conventional KMNF noise estimation (KMNF-NE) uses the local regress...
Article
Full-text available
In precision agriculture, efficient fertilization is one of the most important pursued goals. Vegetation spectral profiles and the corresponding spectral parameters are usually employed for vegetation growth status indication, i.e., vegetation classification, bio-chemical content mapping, and efficient fertilization guiding. In view of the fact tha...
Article
Full-text available
Nowadays, the Inertial Navigation System/Global Navigation Satellite System (INS/GNSS) integrated navigation system is widely used in many applications. The extended Kalman Filter (EKF) is a popular data fusion method for the INS/GNSS integrated navigation system. However, the process and measurement noise covariance matrices of the EKF cannot be m...
Presentation
Full-text available
Forest dynamics monitoring with a Permanent Lidar Phenology station
Article
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The paper investigates the penetration properties of an airborne Ku-band frequency modulated continuous waveform (FMCW) profiling radar named Tomoradar and a satellite near-infrared lidar into the boreal forest of Finland. We achieve the accumulative energy distributions based on the Tomoradar waveforms and the satellite lidar waveforms generated f...
Article
Full-text available
Hyperspectral LiDAR (HSL) is a new remote sensing detection method with high spatial and spectral information detection ability. In the process of laser scanning, the laser echo intensity is affected by many factors. Therefore, it is necessary to calibrate the backscatter intensity data of HSL. Laser incidence angle is one of the important factors...
Article
Full-text available
Profile radar allows direct characterization of the vertical forest structure. Short-wavelength, such as Ku or X band, microwave data provide opportunities to detect the foliage. In order to exploit the potential of radar technology in forestry applications, a helicopter-borne Ku-band profile radar system, named Tomoradar, has been developed by the...
Article
Full-text available
The terrestrial laser scanner (TLS) has become standard technology for vegetation dynamics monitoring. TLS time series have significant underlying application in investigating structural development and dynamics on a daily and seasonal scale. However, the high potential of TLS for the monitoring of long-term temporal phenomena in fully grown trees...
Article
Full-text available
The dihedral angle errors (DAEs) and flatness errors of a nonideal corner cube retroreflector (CCR) determine a ground-based optical instrument’s received optical power. The smaller tolerance of the dihedral angle with lower divergence is theoretically beneficial to improving the received optical power but could increase the difficulty in the fabri...
Article
Full-text available
Light Detection and Ranging (LiDAR) sensors are popular in Simultaneous Localization and Mapping (SLAM) owing to their capability of obtaining ranging information actively. Researchers have attempted to use the intensity information that accompanies each range measurement to enhance LiDAR SLAM positioning accuracy. However, before employing LiDAR i...
Article
Two-dimensional (2D) semiconductors of graphene, as well as transition–metal dichalcogenides, have performed strong interaction with light. Here the strong light–matter interaction between monolayer tungsten disulphide (WS2) excitons and microcavity photons at room temperature is well studied by the introduction of a gain material embedded dielectr...
Article
Commonly, there are two different types of signal tracking methods in Global Navigation Satellite System (GNSS) receivers: Scalar Tracking (ST) and Vector Tracking (VT). In ST, each tracking channel works independently and generates the measurements for Position, Velocity and Time (PVT) estimation. On the contrary, VT accomplishes the signal tracki...
Article
In the conventional GNSS receiver, pseudo-range and pseudo-range rates measurements are generated through carrier signal tracking and code tracking respectively. Then, Least Square method (LSM) or Kalman filter (KF) is utilized to estimate the position and velocity (PV) regarding the pseudo-range and pseudo-range rates as the measurements. However,...
Article
Full-text available
A new method is proposed for selecting Access Points (APs) with propagation direction combination based on Eight-Diagram for indoor localization in indoor environments, which can not only improve positioning accuracy, but also reduce computational complexity by using fewer APs. With propagation direction combination based on eight basic directions,...
Article
Full-text available
Integration of global navigation satellite system and strap-down inertial navigation system in pseudo-range and pseudo-range rate measurements level has been demonstrated an effective way to provide more reliable navigation solutions. Under this condition, the dimension of measurements matrix of the integration filter increases dramatically along w...
Article
Full-text available
This paper analyzes the backscatter of the microwave signal in a boreal forest environment based on a Ku -band airborne Frequency-Modulated Continuous Waveform (FMCW) profiling radar—Tomoradar. We selected a half-managed boreal forest in the southern part of Finland for a field test. By decomposing the waveform collected by the Tomoradar, the verti...
Article
Full-text available
Radar scientists typically define the radar beamwidth as a half-power beamwidth (HPBW) in the main lobe of the antenna pattern. However, the microwave radiations outside radar HPBW might also backscatter into the radar receiver and change the distribution of the received signal. To determine an actual and effective beamwidth illuminated on the meas...
Article
With the booming demand of indoor position information, Wireless signals (Wi-Fi, Bluetooth, Ultra-Wide-Band etc.) are investigated to construct Indoor Positioning System (IPS). Among these wireless signals, UWB (Ultra-Wide-Band) is recognized as the most promising technology to construct IPS with decimeter-level positioning accuracy. However, there...
Article
Full-text available
Hyperspectral laser radar combines the characteristics of LiDAR and hyperspectral information, and provides more accurate remote sensing detection methods of the extraction of vegetation physiological and biochemical parameters, but its application potential has not been fully explored. In this paper, the leaves of 10 typical tree species in Beijin...
Article
Ultra-Wide-Band (UWB) was recognized as its great potential in constructing accurate indoor position system (IPS). However, indoor environments were full of complex objects, the signals might be reflected by the obstacles. Compared with the Line-Of-Sight (LOS) signal, the signal transmitting path delay contained in None-Line-Of-Sight (NLOS) signal...
Article
Full-text available
LiDAR intensity is associated with the target surface material, which could help the points cloud classification. However, the intensity is also associated with the laser beam incident angle and the transmitting distance, the calibration obstructs its application in points cloud classification. Motivated by this problem, this paper proposed a pract...
Article
Full-text available
With the rapid development of autonomous vehicles, the demand for reliable positioning results is urgent. Currently, the ground vehicles heavily depend on the Global Navigation Satellite System (GNSS) and the Inertial Navigation System (INS) providing reliable and continuous navigation solutions. In dense urban areas, especially narrow streets with...
Article
Full-text available
Hyperspectral light detection and ranging (LiDAR) (HSL) combines the characteristics of hyperspectral imaging and LiDAR techniques into a single instrument without any data registration. It provides more information than hyperspectral imaging or LiDAR alone in the extraction of vegetation physiological and biochemical parameters. However, the laser...
Article
Full-text available
Similar to light detection and ranging (lidar), profile radar can detect forest vertical structure directly. Recently, the first Ku-band profile radar system designed for forest applications, called Tomoradar, has been developed and evaluated in boreal forest. However, the physical relationships between the waveform and forest structure parameters...
Article
Full-text available
The far-field diffraction pattern (FFDP) of a corner cube retroreflector (CCR) determines the energy of a retroreflecting beam in some applications including laser ranging, optical communication, and satellite orbit calibration. The FFDP of an imperfect CCR is investigated analytically for the non-normal incidence of a polarized light beam. We firs...
Article
Full-text available
Hyperspectral LiDAR (HSL) has been widely discussed in recent years, which attracts increasing attention of the researchers in the field of electronic information technology. With the application of supercontinuum laser source, it is now possible to develop an HSL system, which can collect spectral and spatial information of targets simultaneously....
Article
Full-text available
Solar selective absorber is the most critical part of solar water heaters which can be integrated into architecture. A high-performance absorber with solar absorptance α higher than 95% and infrared emissivity ε below 4% is fabricated by sputtering using TiNxOy based multilayers. The highest absorptance is 97.5% and the corresponding energy efficie...
Article
Full-text available
Huizhou-style ancient architecture was one of the most important genres of architectural heritage in China. The architecture employed bricks, woods and stones as raw materials, timber frames as significant structures. For the drawback that the timbers are vulnerable to moisture and atmospheric agents, an ancient timber building is needed frequent p...
Article
Visual place recognition plays an increasing important role in robot navigation, autonomous flight of Unmanned Aerial Vehicle (UAV), personal navigation, and so on. However, some texture-less scenarios and computational cost are still challenges. In order to improve the performance of visual place recognition with low computational complexity in th...
Article
During the mining operation, it is a critical task in coal mines to significantly improve the safety by precision coal mining sorting and rock classification from different layers. It implies that a technique for rapidly and accurately classify coal/rock in-site needs to be investigated and established, which is of significance for improving the co...
Article
Full-text available
Non-contact and active vegetation or plant parameters extraction using hyperspectral information is a prospective research direction among the remote sensing community. Hyperspectral LiDAR (HSL) is an instrument capable of acquiring spectral and spatial information actively, which could mitigate the environmental illumination influence on the spect...
Article
Full-text available
With the development of Micro-Electro-Mechanical-System (MEMS) technology, size and accuracy of Chip Scale Atomic Clock (CSAC) gradually improve, and a commercial CSAC products available, which makes it possible to integrate a CSAC to a handheld GNSS receiver. Published results have demonstrated that CSAC could better the Scalar Tracking Loops (STL...
Article
Road furniture recognition has become a prevalent issue in the past few years because of its great importance in smart cities and autonomous driving. Previous research has especially focussed on pole-like road furniture, such as traffic signs and lamp posts. Published methods have mainly classified road furniture as individual objects. However, mos...
Article
Full-text available
A new simple way for tuning the phase transition temperature (PTT) of VO2 thin films has been proposed to solve the problem of changing the doping ratio by using the dual-target co-sputtering method. A series of samples with W doping ratios of 0%, 0.5%, 1%, 1.5% and 2% have been fabricated by sputtering V films with the power of pure and 2% W-doped...
Article
Full-text available
Hyperspectral LiDAR (HSL) technology can obtain spectral and ranging information from targets by processing the recorded waveforms and measuring the time of flight (ToF). With the development of the supercontinuum laser (SCL), it is technically easier to develop an active hyperspectral LiDAR system that can simultaneously collect both spatial infor...
Article
This paper describes the development of an Airborne Wind Vector Scatterometer for low-resolution wind speed measurements. The scatterometer is designed to meet a wind speed accuracy requirement of 1 m/s. In this ad hoc and low-budget project, the development of the instrument exploited some already existing subsystems. The development started from...
Article
Full-text available
Currently, positioning, navigation, and timing information is becoming more and more vital for both civil and military applications. Integration of the global navigation satellite system and /inertial navigation system is the most popular solution for various carriers or vehicle positioning. As is well-known, the global navigation satellite system...
Article
Full-text available
Chip scale atomic clock (CSAC) is a recently developed low-profile atomic frequency reference device. Researchers have demonstrated CSAC was able to improve the accuracy of Global navigation satellite system (GNSS) receiver positioning results. However, the work was conducted using scalar tracking loops (STL). It is meaningful to investigate CSAC a...