Integration between TLS and UAV photogrammetry techniques for forestry applications

Abstract

Forests are significant resources from an ecological, economic and social point of view. Their protection and management could greatly benefit from a complete knowledge of the shape and distribution of trees in forest stands. To this purpose, aerial surveys, especially through Airborne Laser Scanning (ALS), were carried out in the last years to acquire point clouds to be used in 3D models aimed at achieving an accurate description of tree crowns and terrain. However, airborne data acquisition is expensive and may provide poor results in case of dense foliage. Further, point cloud resolution is not very high, as models with a grid of 2-3 m are usually obtained. In order to implement more accurate 3D forest models, a feasible solution is the integration of point clouds obtained by aerial acquisition (ALS or photogrammetry) for the treetops and the terrain description, with information from terrestrial surveys. In this paper, we investigated the possible integration of point clouds obtained by Terrestrial Laser Scanner (TLS) with those collected by photogrammetric 3D models based on images captured by Unmanned Aerial Vehicle (UAV) in a test site located in northern Italy, with the aim of creating an accurate dataset of the forest site with high resolution and precision. The limits of ALS and TLS were bridged by aerial photogrammetry at low altitude (and vice versa). A 3D model of the study area was obtained with a resolution of 5 cm and a precision of 3 cm. Such model may be used in a wide range of applications in forestry studies, e.g., the reconstruction of 3D shapes of trees or the analysis of tree growth throught time. The implications of the use of such integrate approach as a support tool for decision-making in forest management are discussed.

The Use of Nadir and Oblique UAV Images for Building Knowledge

“…UAV systems were used first for military purposes [3] and later for civilian ones [4], such as agricultural and forest management (precision farming, assessment of woodlots, fire surveillance, etc.) [5,6], archaeology and cultural heritage surveying (3D documentation and mapping) [7,8], for environmental surveying (land and water monitoring) [9,10], for traffic monitoring (surveillance, travel time estimation, etc.) [11], and for 3D reconstruction [12].…”

The Use of the Uav Images for the Building 3d Model Generation

“…UAV systems were used first for military purposes and later for civilian ones, such as agricultural and forest management (precision farming, assessment of woodlots, fire surveillance, etc.) Aicardi et al, 2016), archaeology and cultural heritage surveying (3D documentation and mapping) (Berni et al, 2009;2011), for 3D reconstruction (Chiabrando et al, 2012. ) and others.…”

Digital Model Ofwalls of Padua Lowrelief

“…smartphones) allowing to simultaneously deal with indoor/outdoor navigation, by the integration of multiple positioning sensors such as inertial sensors, WiFi, UWB (Saeedi et al, 2014, Fissore et al, 2018, Masiero et al, 2015a, and photogrammetric/laser scanning acquisition of georeferenced data (Aicardi et al, 2016, Masiero et al, 2015b. Further work will aim to the integration of such method in a monitoring system (e.g.…”