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An Integrated Method for Coding Trees, Measuring Tree Diameter, and Estimating Tree Positions

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Názov: An Integrated Method for Coding Trees, Measuring Tree Diameter, and Estimating Tree Positions
Autori: Linhao Sun, Luming Fang, Yuhui Weng, Siqing Zheng
Zdroj: Sensors, Vol 20, Iss 1, p 144 (2019)
Informácie o vydavateľovi: MDPI AG
Rok vydania: 2019
Zbierka: Directory of Open Access Journals: DOAJ Articles
Predmety: forest inventory, quick response code technique, ultra-wide band technology, angle sensor, Chemical technology, TP1-1185
Popis: Accurately measuring tree diameter at breast height (DBH) and estimating tree positions in a sample plot are important in tree mensuration. The main aims of this paper include (1) developing a new, integrated device that can identify trees using the quick response (QR) code technique to record tree identifications, measure DBH, and estimate tree positions concurrently; (2) designing an innovative algorithm to measure DBH using only two angle sensors, which is simple and can reduce the impact of eccentric stems on DBH measures; and (3) designing an algorithm to estimate the position of the tree by combining ultra-wide band (UWB) technology and altitude sensors, which is based on the received signal strength indication (RSSI) algorithm and quadrilateral localization algorithm. This novel device was applied to measure ten 10 × 10 m square plots of diversified environments and various tree species to test its accuracy. Before measuring a plot, a coded sticker was fixed at a height of 1.3 m on each individual tree stem, and four UWB module anchors were set up at the four corners of the plot. All individual trees’ DBHs and positions within the plot were then measured. Tree DBH, measured using a tree caliper, and the values of tree positions, measured using tape, angle ruler, and inclinometer, were used as the respective reference values for comparison. Across the plots, the decode rate of QR codes was 100%, with an average response time less than two seconds. The DBH values had a bias of 1.89 mm (1.88% in relative terms) and a root mean square error (RMSE) of 5.38 mm (4.53% in relative terms). The tree positions were accurately estimated; the biases on the x-axis and the y-axis of the tree position were −8.55−14.88 cm and −12.07−24.49 cm, respectively, and the corresponding RMSEs were 12.94−33.96 cm and 17.78−28.43 cm. The average error between the estimated and reference distances was 30.06 cm, with a standard deviation of 13.53 cm. The device is cheap and friendly to use in addition to its high accuracy. Although ...
Druh dokumentu: article in journal/newspaper
Jazyk: English
Relation: https://www.mdpi.com/1424-8220/20/1/144; https://doaj.org/toc/1424-8220; https://doaj.org/article/6b625092c3d9418cb8b307439e59f6bc
DOI: 10.3390/s20010144
Dostupnosť: https://doi.org/10.3390/s20010144
https://doaj.org/article/6b625092c3d9418cb8b307439e59f6bc
Prístupové číslo: edsbas.DDFC6C4A
Databáza: BASE
Popis
Abstrakt:Accurately measuring tree diameter at breast height (DBH) and estimating tree positions in a sample plot are important in tree mensuration. The main aims of this paper include (1) developing a new, integrated device that can identify trees using the quick response (QR) code technique to record tree identifications, measure DBH, and estimate tree positions concurrently; (2) designing an innovative algorithm to measure DBH using only two angle sensors, which is simple and can reduce the impact of eccentric stems on DBH measures; and (3) designing an algorithm to estimate the position of the tree by combining ultra-wide band (UWB) technology and altitude sensors, which is based on the received signal strength indication (RSSI) algorithm and quadrilateral localization algorithm. This novel device was applied to measure ten 10 × 10 m square plots of diversified environments and various tree species to test its accuracy. Before measuring a plot, a coded sticker was fixed at a height of 1.3 m on each individual tree stem, and four UWB module anchors were set up at the four corners of the plot. All individual trees’ DBHs and positions within the plot were then measured. Tree DBH, measured using a tree caliper, and the values of tree positions, measured using tape, angle ruler, and inclinometer, were used as the respective reference values for comparison. Across the plots, the decode rate of QR codes was 100%, with an average response time less than two seconds. The DBH values had a bias of 1.89 mm (1.88% in relative terms) and a root mean square error (RMSE) of 5.38 mm (4.53% in relative terms). The tree positions were accurately estimated; the biases on the x-axis and the y-axis of the tree position were −8.55−14.88 cm and −12.07−24.49 cm, respectively, and the corresponding RMSEs were 12.94−33.96 cm and 17.78−28.43 cm. The average error between the estimated and reference distances was 30.06 cm, with a standard deviation of 13.53 cm. The device is cheap and friendly to use in addition to its high accuracy. Although ...
DOI:10.3390/s20010144