检索结果-南通市图书馆

Seamless integration of above-and undercanopy unmanned aerial vehicle laser scanning for forest investigation

Forest Ecosystems 2021年第1期8卷 124-138页

作者： Yunsheng Wang Antero Kukko Eric hyyppä Teemu Hakala Jiri Pyörälä Matti Lehtomäki Aimad El Issaoui Xiaowei Yu Harri Kaartinen Xinlian Liang juha hyypp?ä Department of Remote Sensing and Photogrammetry Finnish Geospatial Research Institute FGIThe National Land Survey of Finland02431 MasalaFinland Department of Forest Sciences University of HelsinkiFI-00014 HelsinkiFinland Department of Geography and Geology University of TurkuFI-20500 TurkuFinland

Background:Current automated forest investigation is facing a dilemma over how to achieve high tree-and plotlevel completeness while maintaining a high cost and labor *** study tackles the challenge by exploring a new concept that enables an efficient fusion of aerial and terrestrial perspectives for digitizing and characterizing individual trees in forests through an Unmanned Aerial Vehicle(UAV)that flies above and under canopies in a single *** advantage of such concept is that the aerial perspective from the above-canopy UAV and the terrestrial perspective from the under-canopy UAV can be seamlessly integrated in one flight,thus grants the access to simultaneous high completeness,high efficiency,and low ***:In the experiment,an approximately 0.5 ha forest was covered in ca.10 min from takeoff to *** GNSS-IMU based positioning supports a geometric accuracy of the produced point cloud that is equivalent to that of the mobile mapping systems,which leads to a 2–4 cm RMSE of the diameter at the breast height estimates,and a 4–7 cm RMSE of the stem curve ***:Results of the experiment suggested that the integrated flight is capable of combining the high completeness of upper canopies from the above-canopy perspective and the high completeness of stems from the terrestrial ***,it is a solution to combine the advantages of the terrestrial static,the mobile,and the above-canopy UAV observations,which is a promising step forward to achieve a fully autonomous in situ forest *** studies should be aimed to further improve the platform positioning,and to automatize the UAV operation.

关键词： Forest In situ Inventory Above canopy Under canopy Unmanned aerial vehicle Laser scanning Point cloud Close range remote sensing

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A practical method utilizing multi-spectral LiDAR to aid points cloud matching in SLAM

引用

Satellite Navigation 2020年第1期1卷 317-327页

作者： Changhui Jiang Yuwei Chen Wenxin Tian Ziyi Feng Wei Li Chunchen Zhou Hui Shao Eetu Puttonen juha hyypp?ä Department of Remote Sensing and Photogrammetry Finnish Geospatial Research Institute(FGI)02430 MasalaFinland Interdisciplinary Division of Aeronautical and Aviation Engineering The Hong Kong Polytechnic UniversityKowloonHong KongChina Key Laboratory of Quantitative Remote Sensing Information Technology Chinese Academy of Sciences(CAS)Beijing 100094China School of Electrical Engineering Aalto University02150 EspooFinland The School of Electronic and Information Engineering Anhui Jianzhu UniversityHefei 230601China

Light Detection and Ranging(LiDAR)sensors are popular in Simultaneous Localization and Mapping(SLAM)owing to their capability of obtaining ranging information *** have attempted to use the intensity information that accompanies each range measurement to enhance LiDAR SLAM positioning ***,before employing LiDAR intensities in SLAM,a calibration operation is usually carried out so that the intensity is independent of the incident angle and *** range is determined from the laser beam transmitting ***,the key to using LiDAR intensities in SLAM is to obtain the incident angle between the laser beam and target *** a complex environment,it is difficult to obtain the incident angle *** procedure also complicates the data processing in SLAM and as a result,further application of the LiDAR intensity in SLAM is *** by this problem,in the present study,we propose a Hyperspectral LiDAR(HSL)-based-intensity calibration-free method to aid point cloud matching in *** employed in this study can obtain an eight-channel range accompanied by corresponding intensity *** to the design of the laser,the eight-channel range and intensity were collected with the same incident angle and *** to the laser beam radiation model,the ratio values between two randomly selected channels’intensities at an identical target are independent of the range information and incident *** test the proposed method,the HSL was employed to scan a wall with different coloured papers pasted on it(white,red,yellow,pink,and green)at four distinct positions along a corridor(with an interval of 60 cm in between two consecutive positions).Then,a ratio value vector was constructed for each *** ratio value vectors between consecutive laser scans were employed to match the point cloud.A classic Iterative Closest Point(ICP)algorithm was employed to estimate the HSL motion using the range information from t

关键词： SLAM Laser intensity LiDAR Calibration

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Automated registration of wide-baseline point clouds in forests using discrete overlap search

引用

Forest Ecosystems 2022年第6期9卷 852-877页

作者： Onni Pohjavirta Xinlian Liang Yunsheng Wang Antero Kukko Jiri Pyorala Eric hyyppa Xiaowei Yu Harri Kaartinen juha hyypp?a Department of Remote Sensing and Photogrammetry Finnish Geospatial Research InstituteVuorimiehentie 5Espoo02150Finland The State Key Laboratory of Information Engineering in Surveying Mapping and Remote SensingWuhan UniversityWuhan430070China Department of Forest Sciences University of HelsinkiHelsinkiFI-00014Finland Department of Geography and Geology University of TurkuTurkuFI-20500Finland

Forest is one of the most challenging environments to be recorded in a three-dimensional(3D)digitized geometrical representation,because of the size and the complexity of the environment and the data-acquisition constraints brought by on-site *** studies have indicated that the data-acquisition pattern can have more influence on the registration results than other *** practice,the ideal short-baseline observations,i.e.,the dense collection mode,is rarely feasible,considering the low accessibility in forest environments and the commonly limited labor and time *** wide-baseline observations that cover a forest site using a few folds less observations than short-baseline observations,are therefore more preferable and commonly ***,the wide-baseline approach is more challenging for data registration since it typically lacks the required sufficient overlaps between *** now,a robust automated registration solution that is independent of special hardware requirements has still been *** is,the registration accuracy is still far from the required level,and the information extractable from the merged point cloud using automated registration could not match that from the merged point cloud using manual *** paper proposes a discrete overlap search(DOS)method to find correspondences in the point clouds to solve the low-overlap problem in the wide-baseline point *** proposed automatic method uses potential correspondences from both original data and selected feature points to reconstruct rough observation geometries without external knowledge and to retrieve precise registration parameters at *** extensive experiment was carried out with 24 forest datasets of different conditions categorized in three difficulty *** performance of the proposed method was evaluated using various accuracy criteria,as well as based on data acquired from different hardware,platforms,viewing persp

关键词： Close-range sensing Forest Registration Point cloud Wide-baseline Terrestrial laser scanning Unmanned aerial vehicle Drone In situ Discrete overlap search

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

高光谱激光雷达：三维生物物理化学生态测量学

引用

遥感信息 2017年第1期32卷 5-9页

作者：林沂 Eetu PUTTONEN juha hyypp?A 北京大学地球与空间科学学院北京100871 芬兰地球空间研究所芬兰马萨拉FI-02430

生态测量学为生态学、地理学、林学、野生生物学等提供基础的技术支撑,开发适应上述学科发展的新型生态测量技术日渐重要,尤其随着目前生物地球化学的快速推进,开发三维生物物理化学生态测量技术成为当前的研究热点,然而当前的主流遥感... 详细信息

生态测量学为生态学、地理学、林学、野生生物学等提供基础的技术支撑,开发适应上述学科发展的新型生态测量技术日渐重要,尤其随着目前生物地球化学的快速推进,开发三维生物物理化学生态测量技术成为当前的研究热点,然而当前的主流遥感测量技术仍无法做到高效准确。高光谱激光雷达技术的发展为解决该问题提供了可能,这也通过基于连续测量的3种单木高光谱激光雷达数据实现反演光合有效辐射、树冠叶绿素含量与氮含量的三维分布及其昼夜变化趋势得到验证。实验结果预示随着高光谱激光雷达的成熟,三维生物物理化学生态测量学将得以建立,相应的三维生物物理化学生态测量技术将进一步推动地理学、生态学、生物地球化学乃至地球系统科学的发展。

关键词：高光谱激光雷达三维生物物理化学生态测量学叶绿素含量光合有效辐射分量氮含量

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Detailed Analysis of Chip Scale Atomic Clock Impact on Satellite Signal Collaborative Tracking

Detailed Analysis of Chip Scale Atomic Clock Impact on Satel...

引用

第十二届中国卫星导航年会

作者： Changhui Jiang Yu Chen Shuai Chen Bohao Wang Yuwei Chen juha hyypp?? School of Automation Nanjing University of Science and Technology

Vector Tracking Loop（VTL） is an advanced satellite signal tracking method for obtaining better navigation solutions under signal challenging environments. In VTL, a navigation filter is employed for estimating the navigation solutions using the measurements from the Code/Frequency discriminators. The measurements from the discriminators are obtained from the integration of local and received signal correlation results. Mutual aiding between channels is realized through the navigation solutions collaborative estimation. However, local frequency base or time reference definitely has significant impact on the discriminator’s outputs. A better local clock with more stable frequency will augment the VTL signal tracking performance. Chip Scale Atomic Clock is a recently popular frequency base for various applications;it performs much better timekeeping capacity than traditional Temperature Compensate X’tal（crystal） Oscillator（TCXO）. In this paper, the CSAC’s influence on the discriminators outputs and signal tracking were analyzed and presented, and specifically, following two problems were investigated: 1) how the CSAC improves the discriminators measurements and the numerical results were presented;2) how the CSAC influence the signal tracking, the new signal tracking parameters calculation was presented with CSAC as the time reference. Finally, an immediate frequency data was utilized to validate the analysis, the results showed that the CSAC could reduce the Doppler error and Code phase error;the Clock drift could be excluded while updating the signal tracking parameters.

关键词： Vector tracking Graph Optimization Covariance Adaptation

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

建筑物自动变化检测方法的测试

引用

地壳构造与地壳应力 2012年第2期 8-16页

作者： Nicolas Champion Franz Rottensteiner Leena Matikainen Xinlian Liang juha hyypp? Brian P.Olsen 李成龙 IGN MATISSaint-MandéFrance Institute of Photogrammetry and Geo Information Leibniz Universitt Hannover FGI Dept.of Remote Sensing and PhotogrammetryMasalaFinland National Survey and Cadastre(KMS) CopenhagenDenmark

数据库的更新(尤其是二维建筑物数据库)已经成为一个热门话题,特别是在较为发达的国家。在这些国家里,二维建筑物数据库已经在近十年来完成。主要问题集中在长期及费时的变化检测步骤,这些步骤可能通过最近获取的传感器数据实现自动化... 详细信息

数据库的更新(尤其是二维建筑物数据库)已经成为一个热门话题,特别是在较为发达的国家。在这些国家里,二维建筑物数据库已经在近十年来完成。主要问题集中在长期及费时的变化检测步骤,这些步骤可能通过最近获取的传感器数据实现自动化。目前在此领域的自动化与经验的缺乏已经促使EuroSDR开展一项当前最先进的不同变化检测方法比较的实验。本文的主要目的是介绍实验的背景和三种不同数据(航拍图像、卫星图像和激光雷达)获得的结果。此外,我们给出了实验中的一些发现以及未来为了建立一个有效的系统所要努力的方向。

关键词：变化检测建筑物基础 Champion 卫星图像传感器数据检测步骤新建筑物标记图对象检测矢量数据

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

From Finnish Assortment Pricing to Market Economy Using Prices for Sawn Wood and Chips in Reference Bucking

引用

Open Journal of Forestry 2024年第3期14卷 233-280页

作者： juha Lappi Faculty of Environmental Sciences and Natural Resource Management Norwegian University of Life Sciences s Norway

Dominant Finnish assortment pricing gives prices for sawlog and pulp wood volumes. Buyers buck stems to sawlogs using secret price matrices. Agreed dimensions allow wide range of sawlog volumes. Forest owners cannot objectively compare biddings: timber trade is a lottery game. Bucking is analyzed in terms of sawlog, pulp wood, log cylinder, sawn wood, value-weighted sawn wood, and chips. Sawn wood and its value are computed from top diameter of the sawlog. Profit maximization requires buyers to buck logs producing smaller than maximal value, causing dead weight loss. Nominal assortment prices have unpredictable relation to effective stumpage price. Assortment pricing does not meet requirements of market economy. If sawmills linked to pulp mills buck smaller sawlog percentages than independent sawmills, as generally believed, they use higher price for chips in their own harvests than they pay for independent sawmills, indicating imperfect competition for chips. Sawn wood potential pricing is suggested which gives prices for sawn wood and chips coming both from sawlogs and pulp wood in reference bucking which maximizes sawn wood for given minimum and maximum log length and minimum top diameter. Simple algorithm generates feasible bucking schedules from which optimum can be selected using any objective. Pricing produces unit price for all commercial wood utilizing ratio of theoretical sawn wood and commercial volume in stand. Unit price can be compared to stem pricing and could be compared to assortment pricing if assortment pricing would produce predictable sawlog percentages. Sawn wood potential pricing is concrete, transparent, easy to compute, considers stem size and tapering, reduces trading cost and is less risky to buyers than stem pricing. It meets requirements of market economy. Readers can repeat computations using open-source software Jlp22.

关键词： Sawmill Pulp Mill Jlp22 Dead Weight Loss Stem Price

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Estimation of drag forces caused by natural woody vegetation of different scales

引用

Journal of Hydrodynamics 2014年第4期26卷 608-623页

作者： JALONEN Johanna JRVEL juha Department of Civil and Environmental Engineering Aalto University

To reliably estimate water levels and velocities in vegetated rivers and floodplains, flow resistance models based on physical plant properties are advantageous. The purpose of this study is （1） to assess the suitable parameterization of woody riparian vegetation in estimating the drag forces, （2） to address the effect of plant scale on the drag estimates and reconfiguration, and （3） to evaluate the applicability of three recently developed flow resistance models. Experiments on four tree species in a towing tank together with detailed characterization of tree properties were carried out to establish a novel dataset. Despite the variability in the tree height （0.9 m-3.4 m）, the stem, leaf and total areas proved to be suitable characteristic dimensions for estimating the flow resistance at different scales. Evaluations with independent data revealed that the tested models produced reasonable results. The performance of the models was controlled by the parameter values used rather than the model structure or the plant scale.

关键词： drag force flow resistance woody vegetation modelling

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

The comparison of design airflow rates with dynamic and steady-state displacement models in varied dynamic conditions

引用

Building Simulation 2021年第4期14卷 1201-1219页

作者： Natalia Lastovets Risto Kosonen juha Jokisalo Department of Mechanical Engineering Aalto UniversityEspooFinland College of Urban Construction Nanjing Tech UniversityNanjingChina

A temperature-based method is usually applied in displacement ventilation (DV) design when overheating is the primary indoor climate concern. Different steady-state models have been developed and implemented to calculate airflow rate in rooms with DV. However, in practical applications, the performance of DV depends on potentially dynamic parameters, such as strength, type and location of heat gains and changing heat gain schedule. In addition, thermal mass affects dynamically changing room air temperature. The selected steady-state and dynamic models were validated with the experimental results of a lecture room and an orchestra rehearsal room. Among the presented models, dynamic DV model demonstrated a capability to take into account the combination of dynamic parameters in typical applications of DV. The design airflow rate is calculated for the case studies of dynamic DV design in the modelled lecture room in both dynamic and steady-state conditions. In dynamic conditions of heavy construction in 2–4 hours occupancy periods, the actual airflow rate required could be 50% lower than the airflow rate calculated with the steady-state models. The difference between steady-state and dynamic multi-nodal model is most significant with heavyweight construction and short occupancy period (17%–28%). In cases with light construction, the dynamic DV model provides roughly the same airflow rates for four-hour occupancy period than the Mund’s model calculates. The dynamic model can significantly decrease the design airflow rate of DV, which can result in a reduction of investment costs and electrical consumption of fans.

关键词： displacement ventilation design airflow rate temperature gradient dynamic model simplified building energy models

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Geometrically modeling 2D scattered points: a review of the potential for methodologically improving mobile laser scanning in data processing

引用

International Journal of Digital Earth 2014年第6期7卷 432-449页

作者： Yi Lin juha hyypp?a Department of Remote Sensing and Photogrammetry Finnish Geodetic Institute MasalaFinland

As a state-of-the-art mapping technology,mobile laser scanning(MLS)is increasingly applied to fields such as digital presentations of city ***,its application has recently met a bottleneck in data *** has been found that conventional methods for geometrically modeling 3D scattered points are inadequate when dealing with large volumes of MLS *** fact,this is a challenge that has already been noted in the MLS-relevant fields,*** sensing,robot perception,and pattern recognition.A variety of algorithms under the schematic frame of analysis,modeling and synthesis(AMS)have been developed in these *** AMS paradigm is to first extract the implicit geometric primitives within each scan profile by geometrically modeling its 2D scattered points(GM2P).The resultant 2D geometric primitives are then integrated to restore the real 3D geometrical *** this process,GM2P is a kernel procedure whereby a review of the GM2P algorithms is assumed to be of significance for developing new efficient algorithms for geometrically modeling 3D scattered *** idea is supported by MLS sampling often being executed via parallel scan ***,the results of the literature review indicate an avenue for methodologically improving MLS in data processing.

关键词： MLS geometrically modeling scattered points GM2P AMS scan profile

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：