scholarly journals Accuracy Assessment of Total Stem Volume Using Close-Range Sensing: Advances in Precision Forestry

Forests ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 717
Author(s):  
Dimitrios Panagiotidis ◽  
Azadeh Abdollahnejad
Keyword(s):  
Convex Hull ◽  
Laser Scanning ◽  
Accuracy Assessment ◽  
Volume Estimation ◽  
Tree Level ◽  
Stem Volume ◽  
Stem Height ◽  
Forest Management Planning ◽  
Close Range ◽  
Precision Forestry

Accurate collection of dendrometric information is essential for improving decision confidence and supporting potential advances in forest management planning (FMP). Total stem volume is an important forest inventory parameter that requires high accuracy. Terrestrial laser scanning (TLS) has emerged as one of the most promising tools for automatically measuring total stem height and diameter at breast height (DBH) with very high detail. This study compares the accuracy of different methods for extracting the total stem height and DBH to estimate total stem volume from TLS data. Our results show that estimates of stem volume using the random sample consensus (RANSAC) and convex hull and HTSP methods are more accurate (bias = 0.004 for RANSAC and bias = 0.009 for convex hull and HTSP) than those using the circle fitting method (bias = 0.046). Furthermore, the RANSAC method had the best performance with the lowest bias and the highest percentage of accuracy (78.89%). The results of this study provide insight into the performance and accuracy of the tested methods for tree-level stem volume estimation, and allow for the further development of improved methods for point-cloud-based data collection with the goal of supporting potential advances in precision forestry.

Analysis of stand density effects on the stem form of Norway spruce trees and volume miscalculation by traditional form factor equations using terrestrial laser scanning (TLS)

2020 ◽  
Vol 50 (1) ◽  
pp. 51-64 ◽  
Author(s):  
Martin Jacobs ◽  
Andreas Rais ◽  
Hans Pretzsch
Keyword(s):  
Form Factor ◽  
Norway Spruce ◽  
Laser Scanning ◽  
Terrestrial Laser Scanning ◽  
Volume Estimation ◽  
Tree Level ◽  
Stem Volume ◽  
Stem Form ◽  
Stem Wood ◽  
Volume Estimates

Tree and stand volume estimates are relevant for forest inventories, forest sales, and carbon stock evaluations. Forest practice commonly uses generalized stem-wood volume functions; however, such generalized approaches neglect the stem form in detail. Hence, trees of a given species with the same diameter at breast height (d1.3) and height (h) are always assumed to have the same form factor and thus the same volume. This case study focused on stem form variation of Norway spruce (Picea abies (L.) Karst.) due to competition effects. Using terrestrial laser scanning (TLS), we measured the stem shape of 868 trees from a long-term spacing and thinning experiment in Germany. The plots covered a broad density range. We analysed the effect of competition and compared the TLS-determined stem volume estimates with those determined conventionally. TLS-based volume estimations showed that the lower the competition was, the lower the tree volume was with a given d1.3 and h. Commonly used functions underestimated the volume stock overall by 4.2%, disregarding any levels. At plot level, underestimation varied from 0.7% to 7.0%. At tree level, the volume was under- and over-estimated by −10% to +10%, respectively. The more precise the examination was, the more suitable the application of TLS was for enhancing volume estimation.

scholarly journals The transferability of airborne laser scanning based tree-level models between different inventory areas

2019 ◽  
Vol 49 (3) ◽  
pp. 228-236 ◽  
Author(s):  
Tomi Karjalainen ◽  
Lauri Korhonen ◽  
Petteri Packalen ◽  
Matti Maltamo
Keyword(s):  
Laser Scanning ◽  
Nearest Neighbor ◽  
Airborne Laser Scanning ◽  
Tree Level ◽  
Stem Volume ◽  
K Nearest Neighbor ◽  
Individual Tree ◽  
Tree Detection ◽  
Airborne Laser ◽  
Crown Base Height

In this paper, we examine the transferability of airborne laser scanning (ALS) based models for individual-tree detection (ITD) from one ALS inventory area (A1) to two other areas (A2 and A3). All areas were located in eastern Finland less than 100 km from each other and were scanned using different ALS devices and parameters. The tree attributes of interest were diameter at breast height (Dbh), height (H), crown base height (Cbh), stem volume (V), and theoretical sawlog volume (Vlog) of Scots pine (Pinus sylvestris L.) with Dbh ≥ 16 cm. All trees were first segmented from the canopy height models, and various ALS metrics were derived for each segment. Then only the segments covering correctly detected pines were chosen for further inspection. The tree attributes were predicted using the k-nearest neighbor (k-NN) imputation. The results showed that the relative root mean square error (RMSE%) values increased for each attribute after the transfers. The RMSE% values were, for A1, A2, and A3, respectively: Dbh, 13.5%, 14.8%, and 18.1%; H, 3.2%, 5.9%, and 6.2%; Cbh, 13.3%, 15.3%, and 18.3%; V, 29.3%, 35.4%, and 39.1%; and Vlog, 38.2%, 54.4% and 51.8%. The observed values indicate that it may be possible to employ ALS-based tree-level k-NN models over different inventory areas without excessive reduction in accuracy, assuming that the tree species are known to be similar.

scholarly journals Accuracy assessment of terrestrial laser scanning and digital close range potogrammetry for 3D cultural heritage

2021 ◽  
Author(s):  
Abdullah Taha Ahmed Albourae
Keyword(s):  
Cultural Heritage ◽  
Laser Scanning ◽  
Reference Data ◽  
Accuracy Assessment ◽  
Terrestrial Laser Scanning ◽  
First Case ◽  
Culture Heritage ◽  
Close Range

There are various surveying techniques used in the field of cultural heritage documentation. Close Range Photogrammetry (CRP) and Terrestrial Laser Scanning (TLS) techniques have been widely used in 3D modeling applications. Various research studies integrate these techniques to enhance the quality of the data acquired. The main objective of this research is to assess the accuracy of TLS and CRP. The two methods are applied to two culture heritage case studies, which are located in the historic district in Jeddah, Saudi Arabia. The data obtained from both techniques is compared with data captured using traditional surveying techniques as reference data. The results show that TLS tends to be more accurate than CRP. In the first case study (Bab Makkah), CRP and TLS produced 0.044 m and 0.008 m overall RMS error, respectively; while CRP produced 0.025 m and TLS produced 0.021 m in the second case study (Bab Sharif).

scholarly journals Accuracy assessment of terrestrial laser scanning and digital close range potogrammetry for 3D cultural heritage

2021 ◽  
Author(s):  
Abdullah Taha Ahmed Albourae
Keyword(s):  
Cultural Heritage ◽  
Laser Scanning ◽  
Reference Data ◽  
Accuracy Assessment ◽  
Terrestrial Laser Scanning ◽  
First Case ◽  
Culture Heritage ◽  
Close Range

There are various surveying techniques used in the field of cultural heritage documentation. Close Range Photogrammetry (CRP) and Terrestrial Laser Scanning (TLS) techniques have been widely used in 3D modeling applications. Various research studies integrate these techniques to enhance the quality of the data acquired. The main objective of this research is to assess the accuracy of TLS and CRP. The two methods are applied to two culture heritage case studies, which are located in the historic district in Jeddah, Saudi Arabia. The data obtained from both techniques is compared with data captured using traditional surveying techniques as reference data. The results show that TLS tends to be more accurate than CRP. In the first case study (Bab Makkah), CRP and TLS produced 0.044 m and 0.008 m overall RMS error, respectively; while CRP produced 0.025 m and TLS produced 0.021 m in the second case study (Bab Sharif).

scholarly journals Accuracy Assessment of Stonex X-300 Laser Scanner Cameras

2018 ◽  
Vol 24 (11) ◽  
pp. 101
Author(s):  
Luma Khalid Jasim
Keyword(s):  
Laser Scanning ◽  
Accuracy Assessment ◽  
Laser Scanner ◽  
Evaluation Process ◽  
Sufficient Information ◽  
Ground Control Points ◽  
Actual Evaluation ◽  
Close Range ◽  
Multiple Domains ◽  
Actual Accuracy

Assessment the actual accuracy of laboratory devices prior to first use is very important to know the capabilities of such devices and employ them in multiple domains. As the manual of the device provides information and values in laboratory conditions for the accuracy of these devices, thus the actual evaluation process is necessary. In this paper, the accuracy of laser scanner (stonex X-300) cameras were evaluated, so that those cameras attached to the device and lead supporting role in it. This is particularly because the device manual did not contain sufficient information about those cameras. To know the accuracy when using these cameras in close range photogrammetry, laser scanning (stonex X-300) device is used to obtain photos of a board including (23) ground control points on it, those observed from two stations and adjusted by using equations of the 3D adjusted triangulation networks by lengths and angles (hybrid routine). (10) GCPs and (13) checkpoints were used to compare the Root Mean Square Error (RMSE) of checkpoints that result from using laser scan cameras with (RMSE) of the same checkpoints that result from using digital photos (Nikon 5200D). The result of (RMSE) comparison was ) in the X direction, ) in the Y direction and ) in the Z direction.  

scholarly journals Comparison of Backpack, Handheld, Under-Canopy UAV, and Above-Canopy UAV Laser Scanning for Field Reference Data Collection in Boreal Forests

2020 ◽  
Vol 12 (20) ◽  
pp. 3327 ◽  
Author(s):  
Eric Hyyppä ◽  
Xiaowei Yu ◽  
Harri Kaartinen ◽  
Teemu Hakala ◽  
Antero Kukko ◽  
...  
Keyword(s):  
Data Collection ◽  
Point Cloud ◽  
Laser Scanning ◽  
Reference Data ◽  
Tree Height ◽  
Tree Level ◽  
Stem Volume ◽  
Point Cloud Data ◽  
Cloud Data ◽  
Individual Trees

In this work, we compared six emerging mobile laser scanning (MLS) technologies for field reference data collection at the individual tree level in boreal forest conditions. The systems under study were an in-house developed AKHKA-R3 backpack laser scanner, a handheld Zeb-Horizon laser scanner, an under-canopy UAV (Unmanned Aircraft Vehicle) laser scanning system, and three above-canopy UAV laser scanning systems providing point clouds with varying point densities. To assess the performance of the methods for automated measurements of diameter at breast height (DBH), stem curve, tree height and stem volume, we utilized all of the six systems to collect point cloud data on two 32 m-by-32 m test sites classified as sparse (n = 42 trees) and obstructed (n = 43 trees). To analyze the data collected with the two ground-based MLS systems and the under-canopy UAV system, we used a workflow based on our recent work featuring simultaneous localization and mapping (SLAM) technology, a stem arc detection algorithm, and an iterative arc matching algorithm. This workflow enabled us to obtain accurate stem diameter estimates from the point cloud data despite a small but relevant time-dependent drift in the SLAM-corrected trajectory of the scanner. We found out that the ground-based MLS systems and the under-canopy UAV system could be used to measure the stem diameter (DBH) with a root mean square error (RMSE) of 2–8%, whereas the stem curve measurements had an RMSE of 2–15% that depended on the system and the measurement height. Furthermore, the backpack and handheld scanners could be employed for sufficiently accurate tree height measurements (RMSE = 2–10%) in order to estimate the stem volumes of individual trees with an RMSE of approximately 10%. A similar accuracy was obtained when combining stem curves estimated with the under-canopy UAV system and tree heights extracted with an above-canopy flying laser scanning unit. Importantly, the volume estimation error of these three MLS systems was found to be of the same level as the error corresponding to manual field measurements on the two test sites. To analyze point cloud data collected with the three above-canopy flying UAV systems, we used a random forest model trained on field reference data collected from nearby plots. Using the random forest model, we were able to estimate the DBH of individual trees with an RMSE of 10–20%, the tree height with an RMSE of 2–8%, and the stem volume with an RMSE of 20–50%. Our results indicate that ground-based and under-canopy MLS systems provide a promising approach for field reference data collection at the individual tree level, whereas the accuracy of above-canopy UAV laser scanning systems is not yet sufficient for predicting stem attributes of individual trees for field reference data with a high accuracy.

scholarly journals Developing Allometric Equations for Teak Plantations Located in the Coastal Region of Ecuador from Terrestrial Laser Scanning Data

Forests ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 1050 ◽  
Author(s):  
Fernando J. Aguilar ◽  
Abderrahim Nemmaoui ◽  
Alberto Peñalver ◽  
José R. Rivas ◽  
Manuel A. Aguilar
Keyword(s):  
Laser Scanning ◽  
Coastal Region ◽  
Terrestrial Laser Scanning ◽  
Tree Height ◽  
Tree Level ◽  
Stem Volume ◽  
Automatic Data ◽  
Allometric Models ◽  
Teak Plantations ◽  
Tree Stem

Traditional studies aimed at developing allometric models to estimate dry above-ground biomass (AGB) and other tree-level variables, such as tree stem commercial volume (TSCV) or tree stem volume (TSV), usually involves cutting down the trees. Although this method has low uncertainty, it is quite costly and inefficient since it requires a very time-consuming field work. In order to assist in data collection and processing, remote sensing is allowing the application of non-destructive sampling methods such as that based on terrestrial laser scanning (TLS). In this work, TLS-derived point clouds were used to digitally reconstruct the tree stem of a set of teak trees (Tectona grandis Linn. F.) from 58 circular reference plots of 18 m radius belonging to three different plantations located in the Coastal Region of Ecuador. After manually selecting the appropriate trees from the entire sample, semi-automatic data processing was performed to provide measurements of TSCV and TSV, together with estimates of AGB values at tree level. These observed values were used to develop allometric models, based on diameter at breast height (DBH), total tree height (h), or the metric DBH2 × h, by applying a robust regression method to remove likely outliers. Results showed that the developed allometric models performed reasonably well, especially those based on the metric DBH2 × h, providing low bias estimates and relative RMSE values of 21.60% and 16.41% for TSCV and TSV, respectively. Allometric models only based on tree height were derived from replacing DBH by h in the expression DBH2 x h, according to adjusted expressions depending on DBH classes (ranges of DBH). This finding can facilitate the obtaining of variables such as AGB (carbon stock) and commercial volume of wood over teak plantations in the Coastal Region of Ecuador from only knowing the tree height, constituting a promising method to address large-scale teak plantations monitoring from the canopy height models derived from digital aerial stereophotogrammetry.

Combining tree height samples produced by airborne laser scanning and stand management records to estimate plot volume in Eucalyptus plantations

2011 ◽  
Vol 41 (8) ◽  
pp. 1649-1658 ◽  
Author(s):  
Jari Vauhkonen ◽  
Lauri MehtÄtalo ◽  
Petteri Packalén
Keyword(s):  
Laser Scanning ◽  
Tree Height ◽  
Small Sample ◽  
Airborne Laser Scanning ◽  
Tree Level ◽  
Stem Volume ◽  
Data Set ◽  
Stand Management ◽  
Tree Detection ◽  
Airborne Laser

Regular stand structure and availability of precise silvicultural management data produce a special situation regarding remote sensing based assessments of plantation forests. This study tested the use of stand management records to improve single-tree detection in a Eucalyptus plantation. Combined airborne laser scanning (ALS) and planting distance data were used to detect trees and extract their heights. The extracted heights were used as an input for volume estimation using both existing plot-level functions and new tree-level models. The accuracies were evaluated in a test data set of 191 field reference plots in which the diameters of the Eucalyptus urograndis (E. grandis (Hill) Maiden × E. urophylla S.T. Blake) trees varied from 6 to 41 cm and tree heights varied from 12 to 41 m. The constructed mixed-effects model that predicted stem volume from tree height resulted in a root mean squared error (RMSE) of 68 dm3 (15%) in a cross validation of the modeling data. The tree detection produced estimates of stem number with low bias (i.e., average difference between measured and estimated) and an RMSE of 6% of the mean, whereas plot-level mean and dominant heights were estimated with RMSEs of 1.5 m (5%) and 2 m (6%), respectively, using ALS data alone. The difference of about 60 cm observed between the ALS-based and field-measured dominant height was most likely caused by the penetration of the laser pulses through the canopy. A system of plot-level models that employed a small sample of calibration field data gave RMSEs of 1 m (3%) and 2.2 m2/ha (9%) for site index and basal area, respectively. The plot volume was estimated with an RMSE of 44 m3/ha (12%) at best. A similar residual variation was observed in the volume estimates of an area-based method applied to the same data set. The combined results suggest the feasibility of the proposed methodology in a plantation inventory using ALS data with a density of only 1.5 pulses/m2.

scholarly journals Revealing Changes in the Stem Form and Volume Allocation in Diverse Boreal Forests Using Two-Date Terrestrial Laser Scanning

Forests ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 835
Author(s):  
Ville Luoma ◽  
Tuomas Yrttimaa ◽  
Ville Kankare ◽  
Ninni Saarinen ◽  
Jiri Pyörälä ◽  
...  
Keyword(s):  
Tree Growth ◽  
Point Cloud ◽  
Laser Scanning ◽  
Terrestrial Laser Scanning ◽  
Point Clouds ◽  
Stem Volume ◽  
Accurate Information ◽  
Stem Form ◽  
Monitoring Period ◽  
Significant Difference

Tree growth is a multidimensional process that is affected by several factors. There is a continuous demand for improved information on tree growth and the ecological traits controlling it. This study aims at providing new approaches to improve ecological understanding of tree growth by the means of terrestrial laser scanning (TLS). Changes in tree stem form and stem volume allocation were investigated during a five-year monitoring period. In total, a selection of attributes from 736 trees from 37 sample plots representing different forest structures were extracted from taper curves derived from two-date TLS point clouds. The results of this study showed the capability of point cloud-based methods in detecting changes in the stem form and volume allocation. In addition, the results showed a significant difference between different forest structures in how relative stem volume and logwood volume increased during the monitoring period. Along with contributing to providing more accurate information for monitoring purposes in general, the findings of this study showed the ability and many possibilities of point cloud-based method to characterize changes in living organisms in particular, which further promote the feasibility of using point clouds as an observation method also in ecological studies.

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