Measuring tree DBH & height by using terrestrial laser scanner for forest management

Kong, Weibin (2017) Measuring tree DBH & height by using terrestrial laser scanner for forest management. [USQ Project]


Terrestrial laser scanner (TLS) is a modern laser scanning technology has been utilised in surveying industry for many years. Two of the biggest industries utilising TLS technology are building and mining industry. Using TLS for environmental monitoring purposes especially forest tree monitoring and modelling is a relatively new and continuing researched area.

The aim of this project is to collect and extract tree DBH (diameter at breast height) & height information from terrestrial laser scan data by using a free to air modelling software ‘3D Forest’ then verify the accuracy of the extracted data by comparing to manually collected data.

The research area is located in Lake Broadwater, Dalby. It is one of PPBio Australasia’s RAPELD (rapid assessment surveys) long-term ecological research sites. The project site has been divided into 18 plots. A number of laser scan had been carried out by using FARO Focus 3D scanner due to time constraint, only first day of plot scan data will be examined. To obtain tree DBH and height from the scanned data there will be three stage processes: stage one is using FARO SCENE to reduce and georeference the data then stage two is import the point cloud data into ‘3D Forest’ software to extract tree DBH and height information by using least square regression method. The final stage is to compare the scanned data with manually collected field data. In data verification process additional scans were carried out near USQ Toowoomba campus as well as tradition total station survey then both sets of data were compared to verify the scan data accuracy.

Project results show 3D Forest software is capable of generate most tree height and DBH information from registered point cloud (a total of 37 trees were segmented) and the outcome data can be in real-world coordinate system. But the extracted tree DBH and height information is very unreliable and large amount of time manual editing is required to get that information.

The comparison results between scanned data and traditional manually collected data demonstrated the scan data were overestimated tree DBH by average 242 cm and underestimated tree height by average of 210mm. But there are a number of outlier tree DBH value included in the calculation if those outlier were removed the tree DBH difference between scanned data and traditional method collected data were only 49mm compare to 242cm which was a big improvement. In the verification process the result had demonstrated similar outcomes the scanned data were underestimated tree height by average 160mm and overestimated tree DBH by 25mm. Overall the combined use of FARO Focus 3D scanner and 3D Forest programme enabled the author to extract tree DBH and height information with relatively accurate result. But the results were not very reliable 3D Forest is a very useful tool for generating tree inventory information and it has a lot potential in tree data management but because it is an open to air software, thus it has lots of bugs need to be fixed before it can reach its full potential. Using other third party software to extract the same tree information is recommended for future research project.

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Item Type: USQ Project
Item Status: Live Archive
Additional Information: Bachelor of Spatial Science (Honours) (Surveying)
Faculty/School / Institute/Centre: Historic - Faculty of Health, Engineering and Sciences - School of Civil Engineering and Surveying (1 Jul 2013 - 31 Dec 2021)
Supervisors: Liu, Xiaoye
Date Deposited: 07 Sep 2022 03:01
Last Modified: 07 Sep 2022 03:01
Uncontrolled Keywords: Terrestrial laser scanner (TLS); tree height; diameter at breast height (DBH); forest management

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