Abstract
Computer vision technology has promoted the rapid development of forest observation equipment, and video photography (videogrammetry) has provided new ideas and means for forestry investigation. According to the characteristics of videogrammetry, a spiral observation method is proposed. Meanwhile, a new point cloud data processing method is proposed, which extracts a point cloud at the diameter at breast height (DBH) section and determines the DBH of trees through cylinder fitting and circle fitting, according to the characteristics of the point cloud model and the real situation of occlusion in the sampled area, and then calculates the biomass. Through a large number of experiments, a more effective and relatively high-precision method for DBH extraction is obtained. Compared with the field survey data, the bias% of DBH extracted by videogrammetry was −3.19~2.87%, and the RMSE% was 5.52~7.76%. Compared with the TLS data, the bias% of −4.78~2.38%, and the RMSE% was 5.63~9.87%. The above-ground biomass (AGB) estimates from the videogrammetry showed strong agreement with the reference values with concordance correlation coefficient (CCC) and the RMSE values of 0.97 and 19.8 kg. Meanwhile, the AGB estimate from TLS agrees with the CCC values and the RMSE of 0.97 and 17.23 kg. Videogrammetry is not only cheap, low cost, and fast, but also can be observed in a relatively complex forest environment, with strong anti-interference ability. The experimental results prove that its accuracy is comparable to TLS and photogrammetry. Thus this work is quite valuable in a forest resources survey. We believe that the calculation accuracy of our new method can fully meet the needs of the forest survey.
Highlights
Forests are the backbone of terrestrial ecosystems
To confirm the achievability of the videogrammetry method for the extraction of tree measurements, we selected 10 sample plots, each being 20 m × 20 m, in the study area to carry out our experiment
The data quality of the 3D point cloud model, which is established by videogrammetry to extract keyframes, is relatively high
Summary
Forests are the backbone of terrestrial ecosystems. Scientific research on the monitoring and assessment methods of the quantity, quality, spatial distribution and annual changes in forest resources is the basis for tackling major issues such as global climate change, forestry, ecological environment construction, forest rights reform and trading, forest resources management, and the production of timber and forest byproducts. Individual tree diameter at breast height (DBH), individual tree height, individual tree volume, average stand volume, stand height, and stand density are important forest structure factors [1,2,3]. The measurement of forest structures could directly influence the evaluation of the land quality and forest growth [3,4,5]. Portable and efficient measuring equipment and reasonable observation schemes are significantly necessary
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
