The benefits of lidar compared to photogrammetry for forestry applications is the capability for the laser to penetrate through the forest canopy, providing 3D detail of the ground profile, and creating a virtual twin of the forest structure. Here is an example of LiDAR from our drone captured over some tall native forest here in New Zealand. You can see the colorized point cloud and a couple of transect profile views showing the multiple returns penetrating down through the canopy.

Colourised Point Cloud View
5m Transect Profile Through Tree Canopy, Shrubland and Tall Native NZ Forest
5m Transect Profile Through Tall Native NZ Tree Canopy

Lidar continues its evolution as a forester’s tool and is becoming a reality at scale and efficiency for forest stand or woodlot inventory using drones. This data is collected with our DJI Matrice 300RTK UAV and is the latest drone-based LiDAR system developed by LiVox and DJI. This LiVox Avia sensor is combined into the DJI L1 Sensor with a 20MP Camera and high spec IMU.

DJI M300RTK L1 LiDAR Sensor
Interpine’s DJI Matrice 300 RTK with L1 Lidar sensor fitted.
Interpine DJI M300RTK Drone UAV L1 LiDAR Sensor

LiDAR (light detection and ranging) is a scanning technology that actively surveys and measures the environment around it. Fitted to a drone, this provides a 3D model of the world within its reach. Here is a snippet of our drone fitted with the DJI L1 LiDAR sensor scanning the trees / forest around our office and the live 3D point cloud view (right side of the screen) provided to the pilots during data collection.

With this kind of data, the way we assess and measure forests changes. The opportunities for tracking individual trees over time become a reality.

Forest level tree segmentation with LiDAR data
Digital Terrain Model of the Typical Forest Woodlot Derived from Drone Based LiDAR (this being for the Forest Woodlot shown at the start of this article)
Extract of a profile of the normalized point cloud of the trees, colored by height profile, showing every tree being able to be measured for height. The ground returns are also shown on the ground in which the LiDAR gathers by penetrating down through the tree canopy.
Forest Woodlot CHM View
Tree height profile where the color indicates the height of the trees where the terrain has been removed to focus on the standing trees (normalized). This enables the measurement of individual trees for height, and if often referred to as a canopy height model.
And extracting individual trees from the LiDAR data for further forest valuation/inventory analysis. In this case, 5109 trees are present across the forest.
In this example, the trees can be pulled off the landscape and a digital terrain model of the bare earth developed.