A New Algorithm with Distance Constraint for Large-Scale Profile Measurement

2006 ◽  
Vol 326-328 ◽  
pp. 159-162 ◽  
Author(s):  
Yong Qiang Wang ◽  
Nai Guang Lu ◽  
Wen Yi Deng ◽  
Ming Li Dong
2021 ◽  
Vol 17 (4) ◽  
pp. 1-28
Author(s):  
Yuxiang Lin ◽  
Wei Dong ◽  
Yi Gao ◽  
Tao Gu

With the increasing relevance of the Internet of Things and large-scale location-based services, LoRa localization has been attractive due to its low-cost, low-power, and long-range properties. However, existing localization approaches based on received signal strength indicators are either easily affected by signal fading of different land-cover types or labor intensive. In this work, we propose SateLoc, a LoRa localization system that utilizes satellite images to generate virtual fingerprints. Specifically, SateLoc first uses high-resolution satellite images to identify land-cover types. With the path loss parameters of each land-cover type, SateLoc can automatically generate a virtual fingerprinting map for each gateway. We then propose a novel multi-gateway combination strategy, which is weighted by the environmental interference of each gateway, to produce a joint likelihood distribution for localization and tracking. We implement SateLoc with commercial LoRa devices without any hardware modification, and evaluate its performance in a 227,500-m urban area. Experimental results show that SateLoc achieves a median localization error of 43.5 m, improving more than 50% compared to state-of-the-art model-based approaches. Moreover, SateLoc can achieve a median tracking error of 37.9 m with the distance constraint of adjacent estimated locations. More importantly, compared to fingerprinting-based approaches, SateLoc does not require the labor-intensive fingerprint acquisition process.


2011 ◽  
Vol 1 (32) ◽  
pp. 98 ◽  
Author(s):  
Yanxiong Yang ◽  
Jiabo Zhang ◽  
Cuiping Kuang ◽  
Yu Zhang ◽  
Lulu He ◽  
...  

Beach erosion is prevalent on China’s 18,000 km-long coastline, which has been aggravating due to urban development, river-damming and soil and water conservation projects since late 1970s. Beach erosion threatens the health of beaches of bathing places throughout the world. An effective way to defense the beach erosion is beach nourishment. In this paper, the study on an experimental beach nourishment project, which was conducted to provide data and experience for a large-scale project, was detailed. Field survey was conducted to study the performance of the project. Before and after the project, 8 monitoring profiles had been kept measuring along with the berm positions. The beach profile measurement indicates that after a little retreat the beach got relatively equilibrium, while the berm measurement shown a broadened intertidal zone getting stable eventually. In a word, the filled beach was eroded a little but finally got relatively stable in the survey period.


2020 ◽  
Vol 12 (5) ◽  
pp. 770 ◽  
Author(s):  
Cui Yuan ◽  
Peng Gong ◽  
Yuqi Bai

Although the Advanced Topographic Laser Altimeter System (ATLAS) onboard the Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2) was primarily designed for glacier and sea-ice measurement, it can also be applied to monitor lake surface height (LSH). However, its performance in monitoring lakes/reservoirs has rarely been assessed. Here, we report an accuracy evaluation of the ICESat-2 laser altimetry data over 30 reservoirs in China using gauge data. To show its characteristics in large-scale lake monitoring, we also applied an advanced radar altimeter SARAL (Satellite for ARgos and ALtika) and the first laser altimeter ICESat (Ice, Cloud and land Elevation Satellite) to investigate all lakes and reservoirs (>10 km2) in China. We found that the ICESat-2 has a greatly improved altimetric capability, and the relative altimetric error was 0.06 m, while the relative altimetric error was 0.25 m for SARAL. Compared with SARAL and ICESat data, ICESat-2 data had the lowest measurement uncertainty (the standard deviation of along-track heights; 0.02 m vs. 0.17 m and 0.07 m), the greatest temporal frequency (3.43 vs. 1.35 and 1.48 times per year), and the second greatest lake coverage (636 vs. 814 and 311 lakes). The precise LSH profiles derived from the ICESat-2 data showed that most lakes (90% of 636 lakes) had a quasi-horizontal LSH profile (measurement uncertainty <0.05 m), and special methods are needed for mountainous lakes or shallow lakes to extract precise LSHs.


2017 ◽  
Vol 11 (5) ◽  
pp. 716-720 ◽  
Author(s):  
Eiki Okuyama ◽  
◽  
Kohei Konda ◽  
Hiromi Ishikawa

Many error separation techniques to separate a surface profile from the parasitic motion of the instrument using multiple sensors and/or multiple scans have been proposed. In recent years, large-scale surface profile measurements have become required. When a measured surface profile is large, the number of sampling points becomes large. As the result, the influence of random error becomes large. Previously, a multi-step technique for the division of length was used to decide the short scale from the large scale. An important requirement of this multi-step technique for the division of length is to keep high accuracy at several key points. We applied this technique to the integration method for surface profile measurement and proposed a combination of the large-scale integration method and the short-scale integration method. The results of the theoretical analysis, simulation, and experiment show that this combination method decreases the influence of random error propagation for surface profile measurement.


2008 ◽  
Vol 77 (7) ◽  
pp. 075005 ◽  
Author(s):  
Kensuke Oki ◽  
Ryuya Ikezoe ◽  
Takumi Onchi ◽  
Akio Sanpei ◽  
Haruhiko Himura ◽  
...  

Sensors ◽  
2021 ◽  
Vol 21 (1) ◽  
pp. 310
Author(s):  
Liang Chen ◽  
Sheng Jin ◽  
Zhoujun Xia

The application of deep learning is blooming in the field of visual place recognition, which plays a critical role in visual Simultaneous Localization and Mapping (vSLAM) applications. The use of convolutional neural networks (CNNs) achieve better performance than handcrafted feature descriptors. However, visual place recognition is still a challenging task due to two major problems, i.e., perceptual aliasing and perceptual variability. Therefore, designing a customized distance learning method to express the intrinsic distance constraints in the large-scale vSLAM scenarios is of great importance. Traditional deep distance learning methods usually use the triplet loss which requires the mining of anchor images. This may, however, result in very tedious inefficient training and anomalous distance relationships. In this paper, a novel deep distance learning framework for visual place recognition is proposed. Through in-depth analysis of the multiple constraints of the distance relationship in the visual place recognition problem, the multi-constraint loss function is proposed to optimize the distance constraint relationships in the Euclidean space. The new framework can support any kind of CNN such as AlexNet, VGGNet and other user-defined networks to extract more distinguishing features. We have compared the results with the traditional deep distance learning method, and the results show that the proposed method can improve the performance by 19–28%. Additionally, compared to some contemporary visual place recognition techniques, the proposed method can improve the performance by 40%/36% and 27%/24% in average on VGGNet/AlexNet using the New College and the TUM datasets, respectively. It’s verified the method is capable to handle appearance changes in complex environments.


2018 ◽  
Vol 12 (4) ◽  
pp. 582-589 ◽  
Author(s):  
Tatsuya Kume ◽  
Masanori Satoh ◽  
Tsuyoshi Suwada ◽  
Kazuro Furukawa ◽  
Eiki Okuyama ◽  
...  

Profile evaluation by detecting tangential angles of the profile is competent for large objects because it inherently requires no reference, which is difficult to define with sufficient accuracy as the object becomes larger. We considered using a gyro for detecting the angles instead of an inclinometer or an autocollimator, which are conventionally used as angle detectors. A gyro can detect angles without angular reference; therefore, profiles can be evaluated without the limitation of a reference. However, angles detected by a gyro generally have considerable fluctuations to ensure accuracy in the μrad range, which is the same level as a highly precise inclinometer. In this work, we adopted a periodic reversal measurement using a rotating mechanism to eliminate fluctuations. Analysis and experimental results show that the angles of the gyro’s rotating axis against the earth’s rotating axis can be derived from the angular signals of two gyros rotating in counter directions, and that this method is effective for reducing the influences of fluctuations.


2016 ◽  
Vol 21 ◽  
pp. 45-53 ◽  
Author(s):  
Carlos M. Vullo ◽  
Magdalena Romero ◽  
Laura Catelli ◽  
Mustafa Šakić ◽  
Victor G. Saragoni ◽  
...  

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