Search results for: Xinlian Liang

Items from 1 to 18 out of 18 results

article

Quantification of occlusions influencing the tree stem curve retrieving from single-scan terrestrial laser scanning data

Peng Wan, Tiejun Wang, Wuming Zhang, Xinlian Liang, more

Forest Ecosystems > 2019 > 6 > 1 > 1-13

Background The stem curve of standing trees is an essential parameter for accurate estimation of stem volume. This study aims to directly quantify the occlusions within the single-scan terrestrial laser scanning (TLS) data, evaluate its correlation with the accuracy of the retrieved stem curves, and subsequently, to assess the capacity of single-scan TLS to estimate stem curves. Methods We proposed...

article

Forest in situ observations using unmanned aerial vehicle as an alternative of terrestrial measurements

Xinlian Liang, Yunsheng Wang, Jiri Pyörälä, Matti Lehtomäki, more

Forest Ecosystems > 2019 > 6 > 1 > 1-16

Background Lately, terrestrial point clouds have drawn attention as a new data source for in situ forest investigations. So far, terrestrial laser scanning (TLS) has the highest data quality among all terrestrial point cloud data in terms of geometric accuracy and level of detail (IEEE Transact Geosci Remote Sens 53: 5117–5132, 2015). The TLS point clouds processed by automated algorithms can provide...

article

In-situ measurements from mobile platforms: An emerging approach to address the old challenges associated with forest inventories

Xinlian Liang, Antero Kukko, Juha Hyyppä, Matti Lehtomäki, more

ISPRS Journal of Photogrammetry and Remote Sensing > 2018 > 143 > C > 97-107

Accurate assessments of forest resources rely on ground truth data that are collected via in-situ measurements, which are fundamental for all other statistical- and/or remote-sensing-based deductions on quantified forest attributes. The major bottleneck of the current in-situ observation system is that the data collection is time consuming, and, thus, limited in extent, which potentially biases any...

article

A Novel GNSS Technique for Predicting Boreal Forest Attributes at Low Cost

Jingbin Liu, Juha Hyyppa, Xiaowei Yu, Anttoni Jaakkola, more

IEEE Transactions on Geoscience and Remote Sensing > 2017 > 55 > 9 > 4855 - 4867

One of the biggest challenges in forestry research is the effective and accurate measuring and monitoring of forest variables, as the exploitation potential of forest inventory products largely depends on the accuracy of estimates and on the cost of data collection. This paper presented a novel computational method of low-cost forest inventory using global navigation satellite system (GNSS) signals...

article

Automated matching of multiple terrestrial laser scans for stem mapping without the use of artificial references

Jingbin Liu, Xinlian Liang, Juha Hyyppä, Xiaowei Yu, more

International Journal of Applied Earth Observation and Geoinformation > 2017 > 56 > C > 13-23

Terrestrial laser scanning has been widely used to analyze the 3D structure of a forest in detail and to generate data at the level of a reference plot for forest inventories without destructive measurements. Multi-scan terrestrial laser scanning is more commonly applied to collect plot-level data so that all of the stems can be detected and analyzed. However, it is necessary to match the point clouds...

article

Feasibility of Terrestrial laser scanning for collecting stem volume information from single trees

Ninni Saarinen, Ville Kankare, Mikko Vastaranta, Ville Luoma, more

ISPRS Journal of Photogrammetry and Remote Sensing > 2017 > 123 > C > 140-158

Interest in measuring forest biomass and carbon stock has increased as a result of the United Nations Framework Convention on Climate Change, and sustainable planning of forest resources is therefore essential. Biomass and carbon stock estimates are based on the large area estimates of growing stock volume provided by national forest inventories (NFIs). The estimates for growing stock volume based...

article

Temporal and spatial variations of global ionospheric total electron content under various solar conditions

Jingbin Liu, Manuel Hernandez-Pajares, Xinlian Liang, Jiachun An, more

Journal of Geodesy > 2017 > 91 > 5 > 485-502

By utilizing the numerical technique of principal component analysis (PCA), this work analyses temporal and spatial variations of the ionosphere under various solar conditions during the period 1999–2013. Applying the PCA technique to the time series of the global ionospheric total electron content (TEC) maps provides an efficient method for analyzing the main ionospheric variability on a global scale...

article

International Benchmarking of the Individual Tree Detection Methods for Modeling 3-D Canopy Structure for Silviculture and Forest Ecology Using Airborne Laser Scanning

Yunsheng Wang, Juha Hyyppa, Xinlian Liang, Harri Kaartinen, more

IEEE Transactions on Geoscience and Remote Sensing > 2016 > 54 > 9 > 5011 - 5027

Canopy structure plays an essential role in biophysical activities in forest environments. However, quantitative descriptions of a 3-D canopy structure are extremely difficult because of the complexity and heterogeneity of forest systems. Airborne laser scanning (ALS) provides an opportunity to automatically measure a 3-D canopy structure in large areas. Compared with other point cloud technologies...

article

Can global navigation satellite system signals reveal the ecological attributes of forests?

Jingbin Liu, Juha Hyyppä, Xiaowei Yu, Anttoni Jaakkola, more

International Journal of Applied Earth Observation and Geoinformation > 2016 > 50 > C > 74-79

Forests have important impacts on the global carbon cycle and climate, and they are also related to a wide range of industrial sectors. Currently, one of the biggest challenges in forestry research is effectively and accurately measuring and monitoring forest variables, as the exploitation potential of forest inventory products largely depends on the accuracy of estimates and on the cost of data collection...

article

Terrestrial laser scanning in forest inventories

Xinlian Liang, Ville Kankare, Juha Hyyppä, Yunsheng Wang, more

ISPRS Journal of Photogrammetry and Remote Sensing > 2016 > 115 > C > 63-77

Decision making on forest resources relies on the precise information that is collected using inventory. There are many different kinds of forest inventory techniques that can be applied depending on the goal, scale, resources and the required accuracy. Most of the forest inventories are based on field sample. Therefore, the accuracy of the forest inventories depends on the quality and quantity of...

article

Diameter distribution estimation with laser scanning based multisource single tree inventory

Ville Kankare, Xinlian Liang, Mikko Vastaranta, Xiaowei Yu, more

ISPRS Journal of Photogrammetry and Remote Sensing > 2015 > 108 > C > 161-171

Tree detection and tree species recognition are bottlenecks of the airborne remote sensing-based single tree inventories. The effect of these factors in forest attribute estimation can be reduced if airborne measurements are aided with tree mapping information that is collected from the ground. The main objective here was to demonstrate the use of terrestrial laser scanning-derived (TLS) tree maps...

article

Forest Data Collection Using Terrestrial Image-Based Point Clouds From a Handheld Camera Compared to Terrestrial and Personal Laser Scanning

Xinlian Liang, Yunsheng Wang, Anttoni Jaakkola, Antero Kukko, more

IEEE Transactions on Geoscience and Remote Sensing > 2015 > 53 > 9 > 5117 - 5132

Stereo images have long been the main practical data source for the high-accuracy retrieval of 3-D information over large areas. However, stereoscopy has been surpassed by laser scanning (LS) techniques in recent years, particularly in forested areas, because the reflection of laser points from object surfaces directly provides 3-D geometric features and because the laser beam has good penetration...

article

Geostatistical modeling using LiDAR-derived prior knowledge with SPOT-6 data to estimate temperate forest canopy cover and above-ground biomass via stratified random sampling

Wang Li, Zheng Niu, Xinlian Liang, Zengyuan Li, more

International Journal of Applied Earth Observations and Geoinformation > 2015 > 41 > Complete > 88-98

Forest canopy cover (CC) and above-ground biomass (AGB) are important ecological indicators for forest monitoring and geoscience applications. This study aimed to estimate temperate forest CC and AGB by integrating airborne LiDAR data with wall-to-wall space-borne SPOT-6 data through geostatistical modeling. Our study involved the following approach: (1) reference maps of CC and AGB were derived from...

article

Automated Stem Curve Measurement Using Terrestrial Laser Scanning

Xinlian Liang, Ville Kankare, Xiaowei Yu, Juha Hyyppa, more

IEEE Transactions on Geoscience and Remote Sensing > 2014 > 52 > 3 > 1739 - 1748

This paper reports on a study of measuring stem curves of standing trees of different species and in different growth stages using terrestrial laser scanning (TLS). Pine and spruce trees are scanned using the multiscan approach in the field, and trees are felled to measure them destructively for the purpose of obtaining reference values. The stem curves are automatically retrieved from laser point...

article

The Use of a Mobile Laser Scanning System for Mapping Large Forest Plots

Xinlian Liang, Juha Hyyppa, Antero Kukko, Harri Kaartinen, more

IEEE Geoscience and Remote Sensing Letters > 2014 > 11 > 9 > 1504 - 1508

Terrestrial laser scanning (TLS) has been demonstrated to be an efficient measurement method in plot-level forest inventories. A permanent sample plot in national forest inventories is typically a small area of forest with a radius of approximately 10 m. In practice, whether reference data can be automatically and accurately collected for larger plot sizes is of great interest. It is expensive to...

article

Tree mapping using airborne, terrestrial and mobile laser scanning – A case study in a heterogeneous urban forest

Markus Holopainen, Ville Kankare, Mikko Vastaranta, Xinlian Liang, more

Urban Forestry & Urban Greening > 2013 > 12 > 4 > 546-553

We evaluated the accuracy and efficiency of airborne (ALS), terrestrial (TLS) and mobile laser-scanning (MLS) methods that can be utilized in urban tree mapping and monitoring. In the field, 438 urban trees located in park and forested environments were measured and mapped from our study area located in Seurasaari, Helsinki, Finland. A field reference was collected, using a tree map created manually...

article

Automatic Stem Mapping Using Single-Scan Terrestrial Laser Scanning

Xinlian Liang, Paula Litkey, Juha Hyyppa, Harri Kaartinen, more

IEEE Transactions on Geoscience and Remote Sensing > 2012 > 50 > 2 > 661 - 670

The demand for detailed ground reference data in quantitative forest inventories is growing rapidly, e.g., to improve the calibration of the developed models of airborne-laser-scanning-based inventories. The application of terrestrial laser scanning (TLS) in the forest has shown great potential for improving the accuracy and efficiency of field data collection. This paper presents a fully automatic...

chapter

The use of ALS, TLS and VLS measurements in mapping and monitoring urban trees

M Holopainen, M Vastaranta, V Kankare, J Hyyppä, more

2011 Joint Urban Remote Sensing Event > 29 - 32

2011 Joint Urban Remote Sensing Event (JURSE 2011)

We evaluated an accuracy and efficiency of laser measurement methods that can be utilized in urban tree mapping and monitoring. In this paper we describe our methods and show the first results of the study. In the field, altogether 44 urban trees located in park environment were measured and mapped from our pilot area located in Seurasaari, Helsinki, Finland. Several laser scanning methods were compared...

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