Estimation and calibration of stem diameter distribution using UAV laser scanning data: A case study for larch (Larix olgensis) forests in Northeast China

Accurately positioned single-tree data obtained from a cut-to-length harvester were used as training harvester plot data for k-nearest neighbor (k-nn) stem diameter distribution modelling applying airborne laser scanning (ALS) information as predictor variables. Part of the same harvester data were also used for stand-level validation where the validation units were stands including all the harvester plots on a systematic grid located within each individual stand. In the validation all harvester plots within a stand and also the neighboring stands located closer than 200 m were excluded from the training data when predicting for plots of a particular stand. We further compared different training harvester plot sizes, namely 200 m, 400 m, 900 m and 1600 m. Due to this setup the number of considered stands and the areas within the stands varied between the different harvester plot sizes. Our data were from final fellings in Akershus County in Norway and consisted of altogether 47 stands dominated by Norway spruce. We also had ALS data from the area. We concentrated on estimating characteristics of Norway spruce but due to the k-nn approach, species-wise estimates and stand totals as a sum over species were considered as well. The results showed that in the most accurate cases stand-level merchantable total volume could be estimated with RMSE values smaller than 9% of the mean. This value can be considered as highly accurate. Also the fit of the stem diameter distribution assessed by a variant of Reynoldâs error index showed values smaller than 0.2 which are superior to those found in the previous studies. The differences between harvester plot sizes were generally small, showing most accurate results for the training harvester plot sizes 200 m and 400 m.222222

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A Case Study of UAS Borne Laser Scanning for Measurement of Tree Stem Diameter

Remote Sensing ◽

10.3390/rs9111154 ◽

2017 ◽

Vol 9 (11) ◽

pp. 1154 ◽

Cited By ~ 34

Author(s):

Martin Wieser ◽

Gottfried Mandlburger ◽

Markus Hollaus ◽

Johannes Otepka ◽

Philipp Glira ◽

...

Keyword(s):

Laser Scanning ◽

Stem Diameter ◽

Tree Stem

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Analysis of Taper Functions for Larix olgensis Using Mixed Models and TLS

Forests ◽

10.3390/f12020196 ◽

2021 ◽

Vol 12 (2) ◽

pp. 196

Author(s):

Dandan Li ◽

Haotian Guo ◽

Weiwei Jia ◽

Fan Wang

Keyword(s):

Laser Scanning ◽

Mixed Model ◽

Volume Estimation ◽

Stem Diameter ◽

Estimation Accuracy ◽

Larix Olgensis ◽

Stem Analysis ◽

Basic Model ◽

Tree Effect ◽

Taper Function

Terrestrial laser scanning (TLS) plays a significant role in forest resource investigation, forest parameter inversion and tree 3D model reconstruction. TLS can accurately, quickly and nondestructively obtain 3D structural information of standing trees. TLS data, rather than felled wood data, were used to construct a mixed model of the taper function based on the tree effect, and the TLS data extraction and model prediction effects were evaluated to derive the stem diameter and volume. TLS was applied to a total of 580 trees in the nine larch (Larix olgensis) forest plots, and another 30 were applied to a stem analysis in Mengjiagang. First, the diameter accuracies at different heights of the stem analysis were analyzed from the TLS data. Then, the stem analysis data and TLS data were used to establish the stem taper function and select the optimal basic model to determine a mixed model based on the tree effect. Six basic models were fitted, and the taper equation was comprehensively evaluated by various statistical metrics. Finally, the optimal mixed model of the plot was used to derive stem diameters and trunk volumes. The stem diameter accuracy obtained by TLS was >98%. The taper function fitting results of these data were approximately the same, and the optimal basic model was Kozak (2002)-II. For the tree effect, a6 and a9 were used as the mixed parameters, the mixed model showed the best fit, and the accuracy of the optimal mixed model reached 99.72%.The mixed model accuracy for predicting the tree diameter was between 74.22% and 97.68%, with a volume estimation accuracy of 96.38%. Relative height 70 (RH70) was the optimum height for extraction, and the fitting accuracy of the mixed model was higher than that of the basic model.

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Low Temperature Fault Isolation Using Soft Defect Localization

ISTFA 2012: Conference Proceedings from the 38th International Symposium for Testing and Failure Analysis ◽

10.31399/asm.cp.istfa2012p0596 ◽

2012 ◽

Author(s):

Kristopher D. Staller

Keyword(s):

Low Temperatures ◽

Laser Scanning ◽

Low Cost ◽

Fault Isolation ◽

Laser Scanning Microscopy ◽

Cold Temperature ◽

Multiple Point ◽

Defect Localization ◽

Low Levels

Abstract Cold temperature failures are often difficult to resolve, especially those at extreme low levels (< -40°C). Momentary application of chill spray can confirm the failure mode, but is impractical during photoemission microscopy (PEM), laser scanning microscopy (LSM), and multiple point microprobing. This paper will examine relatively low-cost cold temperature systems that can hold samples at steady state extreme low temperatures and describe a case study where a cold temperature stage was combined with LSM soft defect localization (SDL) to rapidly identify the cause of a complex cold temperature failure mechanism.

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Embodiment of Ancestral Spirits, the Social Interface, and Ritual Ceremonies: Construction of the Shamanic Landscape among the Daur in North China

Religions ◽

10.3390/rel12080567 ◽

2021 ◽

Vol 12 (8) ◽

pp. 567

Author(s):

Feng Qu

Keyword(s):

Social Relations ◽

Social Life ◽

Northeast China ◽

North China ◽

Modern Human ◽

The Social ◽

Social Interface ◽

Human Construction ◽

Human Social Life

The case study in this paper is on the Daur (as well as the Evenki, Buriat, and Bargu Mongols) in Hulun Buir, Northeast China. The aim of this research is to examine how shamanic rituals function as a conduit to actualize communications between the clan members and their shaman ancestors. Through examinations and observations of Daur and other Indigenous shamanic rituals in Northeast China, this paper argues that the human construction of the shamanic landscape brings humans, other-than-humans, and things together into social relations in shamanic ontologies. Inter-human metamorphosis is crucial to Indigenous self-conceptualization and identity. Through rituals, ancestor spirits are active actors involved in almost every aspect of modern human social life among these Indigenous peoples.

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