How does LiDAR see through trees

Forests have always been a challenge for researchers and cartographers due to the dense vegetation that obscures the terrain and potential underground objects. However, thanks to modern LiDAR technologies, even the most impenetrable forest areas are now accessible for detailed analysis. Lidar not only allows us to "see" through trees but also to create accurate 3D models of the terrain, aiding in forest inventory, archaeological studies, and even environmental monitoring. If you need to explore a forested area, consider the services of GIS-Point, which specializes in geographic information systems and data processing software.

How Lidar Works in Forested Areas

Lidar in forested areas operates by emitting laser pulses that pass through leaves and branches. Each pulse reflects off different layers—first from the tree canopy, then from the trunks, and finally reaches the ground surface. This allows the LiDAR system to collect multi-layered data, enabling the creation of accurate 3D models of both the forest and the terrain beneath it. This technology allows researchers to "see" through dense vegetation and detect hidden structures on the ground.

How Noise Removal Works

Noise removal during LiDAR operations in forested areas is a key step in obtaining an accurate 3D model of the terrain.

• Data is processed using specialized algorithms that filter out "noise"—reflections from leaves, branches, and other obstacles.
• These algorithms distinguish which points belong to the ground surface and which belong to vegetation or other objects.
• As a result, a clean 3D model of the terrain is generated, allowing for precise study of the surface beneath the trees without the interference of the vegetation cover.

Advantages of Lidar for Forest Mapping

Lidar technology not only measures the Earth's surface but also analyzes the structure of forested areas. Here are a few key advantages of LiDAR for forest mapping:

• Determining Forest Structure. Lidar helps accurately measure tree height, vegetation density, and even the age of the forest.
• Analyzing Terrain Beneath Trees. By sending laser pulses through the tree canopy, LiDAR can create precise 3D maps of the terrain, regardless of forest density.
• Applications in Archaeological and Ecological Research. Lidar allows for the detection of hidden underground structures and the assessment of ecosystem health and climate change impacts on forested areas.

How Lidar is Used in Forests

Lidar is employed in forests to address several critical tasks, providing accurate and detailed data even in remote areas:

• Forest Inventory. Lidar helps create accurate maps of forest resources by measuring tree height, coverage area, and vegetation density, enabling detailed forest condition analysis.
• Biomass and Carbon Footprint Assessment. This is crucial for ecological monitoring and understanding forest carbon storage.
• Detection of Underground Archaeological Sites. Lidar can reveal hidden structures beneath dense vegetation that are difficult to detect with traditional methods.

What Gets in the Way

When using LiDAR in forested areas, certain obstacles can impact the accuracy of the data.

• Tree Density. High vegetation density can lead to a significant amount of reflected signals, creating "noise" in the data and making it difficult to accurately map the lower layers of the forest and soil.
• Air Humidity. High humidity absorbs some of the laser pulses, reducing their power and the accuracy of the reflected signals. Therefore, LiDAR settings are optimized to minimize the impact of humidity on data accuracy. Weather conditions should also be considered during data acquisition
• Technological Limitations in Extreme Forest Density. Most laser pulses reflect off the upper parts of trees, limiting the ability to accurately measure terrain or detect objects underground. High-sensitivity LiDAR systems with adaptive data processing are used in dense forests to reduce noise and accurately measure the terrain beneath vegetation.
• Complex Terrain or Mountainous Areas. Airborne LiDAR is required for quickly collecting data over large areas and processing difficult-to-reach terrains.

Lidar remains one of the best technologies for forest mapping, providing accurate and detailed data even in challenging environments.