scholarly journals Real-Time Vehicle Positioning and Mapping Using Graph Optimization

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2815
Author(s):  
Anweshan Das ◽  
Jos Elfring ◽  
Gijs Dubbelman
Keyword(s):  
Real Time ◽  
Rural Areas ◽  
Low Cost ◽  
Ground Truth ◽  
Visual Odometry ◽  
Graph Optimization ◽  
Urban And Rural Areas ◽  
Vehicle Positioning ◽  
Rate Sensor ◽  
Pose Graph Optimization

In this work, we propose and evaluate a pose-graph optimization-based real-time multi-sensor fusion framework for vehicle positioning using low-cost automotive-grade sensors. Pose-graphs can model multiple absolute and relative vehicle positioning sensor measurements and can be optimized using nonlinear techniques. We model pose-graphs using measurements from a precise stereo camera-based visual odometry system, a robust odometry system using the in-vehicle velocity and yaw-rate sensor, and an automotive-grade GNSS receiver. Our evaluation is based on a dataset with 180 km of vehicle trajectories recorded in highway, urban, and rural areas, accompanied by postprocessed Real-Time Kinematic GNSS as ground truth. We compare the architecture’s performance with (i) vehicle odometry and GNSS fusion and (ii) stereo visual odometry, vehicle odometry, and GNSS fusion; for offline and real-time optimization strategies. The results exhibit a 20.86% reduction in the localization error’s standard deviation and a significant reduction in outliers when compared with automotive-grade GNSS receivers.

scholarly journals RTLIO: Real-Time LiDAR-Inertial Odometry and Mapping for UAVs

Sensors ◽  
2021 ◽  
Vol 21 (12) ◽  
pp. 3955
Author(s):  
Jung-Cheng Yang ◽  
Chun-Jung Lin ◽  
Bing-Yuan You ◽  
Yin-Long Yan ◽  
Teng-Hu Cheng
Keyword(s):  
Feedback Control ◽  
Real Time ◽  
High Frequency ◽  
Indoor Environment ◽  
Indoor Localization ◽  
Sampling Rate ◽  
Outdoor Environment ◽  
Position Accuracy ◽  
Graph Optimization ◽  
Pose Graph Optimization

Most UAVs rely on GPS for localization in an outdoor environment. However, in GPS-denied environment, other sources of localization are required for UAVs to conduct feedback control and navigation. LiDAR has been used for indoor localization, but the sampling rate is usually too low for feedback control of UAVs. To compensate this drawback, IMU sensors are usually fused to generate high-frequency odometry, with only few extra computation resources. To achieve this goal, a real-time LiDAR inertial odometer system (RTLIO) is developed in this work to generate high-precision and high-frequency odometry for the feedback control of UAVs in an indoor environment, and this is achieved by solving cost functions that consist of the LiDAR and IMU residuals. Compared to the traditional LIO approach, the initialization process of the developed RTLIO can be achieved, even when the device is stationary. To further reduce the accumulated pose errors, loop closure and pose-graph optimization are also developed in RTLIO. To demonstrate the efficacy of the developed RTLIO, experiments with long-range trajectory are conducted, and the results indicate that the RTLIO can outperform LIO with a smaller drift. Experiments with odometry benchmark dataset (i.e., KITTI) are also conducted to compare the performance with other methods, and the results show that the RTLIO can outperform ALOAM and LOAM in terms of exhibiting a smaller time delay and greater position accuracy.

Ecological Waste Treatment and Utilization Systems on Low-Cost, Energy-Saving/Generating and Resources Recoverable Technology for Water Pollution Control in China

1991 ◽  
Vol 24 (5) ◽  
pp. 9-19 ◽  
Author(s):  
Baozhen Wang
Keyword(s):  
Pollution Control ◽  
Rural Areas ◽  
Waste Treatment ◽  
Low Cost ◽  
Fish Ponds ◽  
Receiving Waters ◽  
Recoverable Resources ◽  
Urban And Rural Areas ◽  
Rice Fish ◽  
Utilization Of Wastes

Various ecological waste treatment and utilization systems (EWTUS) available in urban and rural areas in China are described, among which are land treatment and utilization systems (LTUS), eco-pond systems mainly consisting of macrohydrophytes-growing ponds, fish ponds and duck/geese ponds, and comprehensive circulation eco–systems for the treatment and utilization of wastes in rural areas, such as semi–closed eco–system in fish ponds, “rice–fish” and “rice–azolla–fish” symbiotic systems, recycling eco–systems with methane-generating digesters as central link, and comprehensive recycling eco–systems with digesters and eco–ponds as central link. In the various EWTUS, the sewage and wastewaters and other wastes are utilized and converted into various forms of recoverable resources and/or energy, while they are being purified to good quality effluents, meeting their respective discharge standards, and hence acceptable to receiving waters.

scholarly journals UHI ESTIMATION BASED ON ASTER AND MODIS SATELLITE IMAGERY: FIRST RESULTS ON STRASBOURG CITY, FRANCE

2020 ◽  
Vol XLIII-B3-2020 ◽  
pp. 799-805
Author(s):  
S. Del Pozo ◽  
T. Landes ◽  
F. Nerry ◽  
P. Kastendeuch ◽  
G. Najjar ◽  
...  
Keyword(s):  
Rural Areas ◽  
Land Surface ◽  
Remote Sensing Data ◽  
Ground Truth ◽  
Area Of Interest ◽  
Air Temperatures ◽  
First Results ◽  
Land Surface Temperatures ◽  
Urban And Rural Areas ◽  
The City

Abstract. The increase in urbanization of cities coupled with some effects of climate change is leading to the emergence of urban microclimates. The rising temperatures in cities create the phenomenon known as Urban Heat Island (UHI). This is a difference between the temperature of urban and rural areas that intensifies more during the night and varies according to the season of the year. This paper focuses on the estimation of the UHI and its variations in and around the city of Strasbourg. To this end, thermal remote sensing data from different satellite has been used to isolate and analyse this phenomenon, specifically, Land Surface Temperatures (LSTs) provided by ASTER and MODIS. The LST provided by these sensors has been compared to air temperatures of the last 15 years from meteorological stations distributed throughout the city that have served as ground truth. Forty-seven meteorological stations spread throughout the area of interest provided measurements of air humidity and temperature. This valuable data base has allowed the assessment of the correlations between LST from satellite and ground truth air temperature. Based on satellite data resampled at different spatial units, this work led to the creation of the first UHI map of Strasbourg.

scholarly journals LOW COST EMBEDDED STEREO SYSTEM FOR UNDERWATER SURVEYS

2017 ◽  
Vol XLII-2/W8 ◽  
pp. 179-186
Author(s):  
M. M. Nawaf ◽  
J.-M. Boï ◽  
D. Merad ◽  
J.-P. Royer ◽  
P. Drap
Keyword(s):  
Embedded System ◽  
Real Time ◽  
Low Cost ◽  
Visual Odometry ◽  
Movement Speed ◽  
Underwater Imaging ◽  
Lighting Conditions ◽  
Computational Resources ◽  
Processing Techniques

This paper provides details of both hardware and software conception and realization of a hand-held stereo embedded system for underwater imaging. The designed system can run most image processing techniques smoothly in real-time. The developed functions provide direct visual feedback on the quality of the taken images which helps taking appropriate actions accordingly in terms of movement speed and lighting conditions. The proposed functionalities can be easily customized or upgraded whereas new functions can be easily added thanks to the available supported libraries. Furthermore, by connecting the designed system to a more powerful computer, a real-time visual odometry can run on the captured images to have live navigation and site coverage map. We use a visual odometry method adapted to low computational resources systems and long autonomy. The system is tested in a real context and showed its robustness and promising further perspectives.

Managed aquifer recharge: rediscovering nature as a leading edge technology

2010 ◽  
Vol 62 (10) ◽  
pp. 2338-2345 ◽  
Author(s):  
P. Dillon ◽  
S. Toze ◽  
D. Page ◽  
J. Vanderzalm ◽  
E. Bekele ◽  
...  
Keyword(s):  
Rural Areas ◽  
Low Cost ◽  
Leading Edge ◽  
Managed Aquifer Recharge ◽  
Aquifer Recharge ◽  
Water Supplies ◽  
Water And Wastewater Treatment ◽  
Urban Hydrogeology ◽  
Urban And Rural Areas ◽  
Treated Sewage Effluent

Use of Managed Aquifer Recharge (MAR) has rapidly increased in Australia, USA, and Europe in recent years as an efficient means of recycling stormwater or treated sewage effluent for non-potable and indirect potable reuse in urban and rural areas. Yet aquifers have been relied on knowingly for water storage and unwittingly for water treatment for millennia. Hence if ‘leading edge’ is defined as ‘the foremost part of a trend; a vanguard’, it would be misleading to claim managed aquifer recharge as a leading edge technology. However it has taken a significant investment in scientific research in recent years to demonstrate the effectiveness of aquifers as sustainable treatment systems to enable managed aquifer recharge to be recognised along side engineered treatment systems in water recycling. It is a ‘cross-over’ technology that is applicable to water and wastewater treatment and makes use of passive low energy processes to spectacularly reduce the energy requirements for water supply. It is robust within limits, has low cost, is suitable from village to city scale supplies, and offers as yet almost untapped opportunities for producing safe drinking water supplies where they do not yet exist. It will have an increasingly valued role in securing water supplies to sustain cities affected by climate change and population growth. However it is not a universal panacea and relies on the presence of suitable aquifers and sources of water together with effective governance to ensure human health and environment protection and water resources planning and management. This paper describes managed aquifer recharge, illustrates its use in Australia, outlining economics, guidelines and policies, and presents some of the knowledge about aquifer treatment processes that are revealing the latent value of aquifers as urban water infrastructure and provide a driver to improving our understanding of urban hydrogeology.

Why DEWATS is Still not Popular in Vietnam?

2010 ◽  
Vol 5 (4) ◽  
Author(s):  
Viet-Anh Nguyen
Keyword(s):  
Rural Areas ◽  
Local Community ◽  
Low Cost ◽  
Wastewater Management ◽  
Limited Information ◽  
Limited Participation ◽  
Management Concept ◽  
Management Schemes ◽  
Urban And Rural Areas ◽  
Local Levels

While large centralized sanitation projects are not affordable for most cases in urban and rural areas, the only way to increase sanitation coverage, especially for the poor, is to implement low-cost alternatives with decentralized sanitation management schemes where local community, administrative authorities and private sectors are involved in the decision making as well as in the exploitation process. Despite of that, there are some reasons discussed why decentralized wastewater management concept and its application is still not widely disseminated throughout Vietnam. Among institutional and managerial aspects there are weaknesses of environmental pollution control capacity at different, especially local levels, limitations of existing Vietnamese environmental standard system, and lacking of incentive measures to encourage consultants to go for the decentralized wastewater concept, as well as to force polluters to improve their situation. In term of finance, discussed pints are low wastewater fee, and limited participation of private sector in the business. In technical aspects, there are limited information of appropriate and proven technical options for different contexts, lessons on their performance and system setting up. Besides, difficulties in the household connection and in collection network are among factors. The paper also provides some examples of decentralized alternatives implemented in different sanitation projects at different scales in Vietnam.

scholarly journals Exploiting Attitude Sensing in Vision-Based Navigation for an Airship

2009 ◽  
Vol 2009 ◽  
pp. 1-16 ◽  
Author(s):  
Luiz G. B. Mirisola ◽  
Jorge Dias
Keyword(s):  
Ground Plane ◽  
Translational Motion ◽  
Ground Truth ◽  
Visual Odometry ◽  
Magnetic Sensors ◽  
Controlled Environment ◽  
Translation Model ◽  
Graph Optimization ◽  
Vision Based Navigation ◽  
Previous Image

An Attitude Heading Reference System (AHRS) is used to compensate for rotational motion, facilitating vision-based navigation above smooth terrain by generating virtual images to simulate pure translation movement. The AHRS combines inertial and earth field magnetic sensors to provide absolute orientation measurements, and our recently developed calibration routine determines the rotation between the frames of reference of the AHRS and the monocular camera. In this way, the rotation is compensated, and the remaining translational motion is recovered by directly finding a rigid transformation to register corresponding scene coordinates. With a horizontal ground plane, the pure translation model performs more accurately than image-only approaches, and this is evidenced by recovering the trajectory of our airship UAV and comparing with GPS data. Visual odometry is also fused with the GPS, and ground plane maps are generated from the estimated vehicle poses and used to evaluate the results. Finally, loop closure is detected by looking for a previous image of the same area, and an open source SLAM package based in 3D graph optimization is employed to correct the visual odometry drift. The accuracy of the height estimation is also evaluated against ground truth in a controlled environment.

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