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New Hybrid Algorithms for Estimating Tree Stem Diameters at Breast Height Using a Two Dimensional Terrestrial Laser Scanner.

Kong J, Ding X, Liu J, Yan L, Wang J - Sensors (Basel) (2015)

Bottom Line: In this paper, a new algorithm to improve the accuracy of estimating diameter at breast height (DBH) for tree trunks in forest areas is proposed.Compared with previous works, this proposed method improves the accuracy of diameter estimation of trees significantly and effectively reduces the calculation time.Moreover, the experimental results indicate that this method is stable and suitable for the most challenging conditions, which has practical significance in improving the operating efficiency of forest harvester and reducing the risk of causing accidents.

View Article: PubMed Central - PubMed

Affiliation: School of Technology, Beijing Forestry University, Beijing 100083, China. kongjianlei_slgc@163.com.

ABSTRACT
In this paper, a new algorithm to improve the accuracy of estimating diameter at breast height (DBH) for tree trunks in forest areas is proposed. First, the information is collected by a two-dimensional terrestrial laser scanner (2DTLS), which emits laser pulses to generate a point cloud. After extraction and filtration, the laser point clusters of the trunks are obtained, which are optimized by an arithmetic means method. Then, an algebraic circle fitting algorithm in polar form is non-linearly optimized by the Levenberg-Marquardt method to form a new hybrid algorithm, which is used to acquire the diameters and positions of the trees. Compared with previous works, this proposed method improves the accuracy of diameter estimation of trees significantly and effectively reduces the calculation time. Moreover, the experimental results indicate that this method is stable and suitable for the most challenging conditions, which has practical significance in improving the operating efficiency of forest harvester and reducing the risk of causing accidents.

No MeSH data available.


Relation histogram of the measured values vs. to the corresponding frequency.
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sensors-15-15661-f007: Relation histogram of the measured values vs. to the corresponding frequency.

Mentions: As shown in Figure 7, the result indicates that the experimental distance values are normally distributed around a measurement value of 2000 mm approximately, which is equal to the actual distance between the object and the 2DTLS. Since the error is distributed in different regions in the range of plus or minus 10 mm, the 95-percent confidence interval of this normal distribution of the fit is plotted in the histogram as follows:(6)m¯−3ξ<Pi<m¯+3ξwhere the initial parameter values Pi represents the distant value of the i-th laser point measured by 2DTLS. The mean or expectation of the distribution is confirm as and its standard deviation is ξ = 2. With the correlation matrix of the fit parameters being tabulated, the true distance values lie within the confidence interval with a confidence level of 95 percent. Considering that the expectation of multiple scanning data is approximate to the desired measuring data, the mean of the distance value of the same laser beam at different moments represents the expectation of the standard normal distribution, which is applied to reduce the fluctuating error. Thus the arithmetic mean method is applied to calculate the distance mean value, which is close to the actual distance value compared with the distance value of one single scanning datum at a random moment. N consecutive samples values are arithmetically averaged with mathematical expression as follows:(7)P¯=1N∑i=1NPiwhere N is the number of scan times and is the arithmetic mean after optimizing. This algorithm reduces the fluctuant error of laser scanner data and promotes the initial raw laser data in a certain degree. With the noisy optimization of all laser beams, the estimation of the trunk diameter with the mean of several repeated laser scans is better than independent single estimates.


New Hybrid Algorithms for Estimating Tree Stem Diameters at Breast Height Using a Two Dimensional Terrestrial Laser Scanner.

Kong J, Ding X, Liu J, Yan L, Wang J - Sensors (Basel) (2015)

Relation histogram of the measured values vs. to the corresponding frequency.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4541849&req=5

sensors-15-15661-f007: Relation histogram of the measured values vs. to the corresponding frequency.
Mentions: As shown in Figure 7, the result indicates that the experimental distance values are normally distributed around a measurement value of 2000 mm approximately, which is equal to the actual distance between the object and the 2DTLS. Since the error is distributed in different regions in the range of plus or minus 10 mm, the 95-percent confidence interval of this normal distribution of the fit is plotted in the histogram as follows:(6)m¯−3ξ<Pi<m¯+3ξwhere the initial parameter values Pi represents the distant value of the i-th laser point measured by 2DTLS. The mean or expectation of the distribution is confirm as and its standard deviation is ξ = 2. With the correlation matrix of the fit parameters being tabulated, the true distance values lie within the confidence interval with a confidence level of 95 percent. Considering that the expectation of multiple scanning data is approximate to the desired measuring data, the mean of the distance value of the same laser beam at different moments represents the expectation of the standard normal distribution, which is applied to reduce the fluctuating error. Thus the arithmetic mean method is applied to calculate the distance mean value, which is close to the actual distance value compared with the distance value of one single scanning datum at a random moment. N consecutive samples values are arithmetically averaged with mathematical expression as follows:(7)P¯=1N∑i=1NPiwhere N is the number of scan times and is the arithmetic mean after optimizing. This algorithm reduces the fluctuant error of laser scanner data and promotes the initial raw laser data in a certain degree. With the noisy optimization of all laser beams, the estimation of the trunk diameter with the mean of several repeated laser scans is better than independent single estimates.

Bottom Line: In this paper, a new algorithm to improve the accuracy of estimating diameter at breast height (DBH) for tree trunks in forest areas is proposed.Compared with previous works, this proposed method improves the accuracy of diameter estimation of trees significantly and effectively reduces the calculation time.Moreover, the experimental results indicate that this method is stable and suitable for the most challenging conditions, which has practical significance in improving the operating efficiency of forest harvester and reducing the risk of causing accidents.

View Article: PubMed Central - PubMed

Affiliation: School of Technology, Beijing Forestry University, Beijing 100083, China. kongjianlei_slgc@163.com.

ABSTRACT
In this paper, a new algorithm to improve the accuracy of estimating diameter at breast height (DBH) for tree trunks in forest areas is proposed. First, the information is collected by a two-dimensional terrestrial laser scanner (2DTLS), which emits laser pulses to generate a point cloud. After extraction and filtration, the laser point clusters of the trunks are obtained, which are optimized by an arithmetic means method. Then, an algebraic circle fitting algorithm in polar form is non-linearly optimized by the Levenberg-Marquardt method to form a new hybrid algorithm, which is used to acquire the diameters and positions of the trees. Compared with previous works, this proposed method improves the accuracy of diameter estimation of trees significantly and effectively reduces the calculation time. Moreover, the experimental results indicate that this method is stable and suitable for the most challenging conditions, which has practical significance in improving the operating efficiency of forest harvester and reducing the risk of causing accidents.

No MeSH data available.