UAV LiDAR systems are capable of collecting an unlimited number of echoes from a single laser pulse. While LiDAR does not penetrate vegetation, if sunlight can reach the forest floor, the laser can too. This allows our systems to identify the crowns of vegetation, the intermediate vertical structures and the soil at the same time. Both in the case of LIDAR and photogrammetry, the sensors do not penetrate through the sheets.
However, the nature of the two methods allows LIDAR to provide information on the ground in densely forested areas that have a narrow canopy. Specifically, lasers fall on a wooded area and some can reach the ground and bounce off. Photogrammetry, which is based on photographs, does not provide as much information on terrains covered by canopies due to the darkness and shadows created by dense masses of trees. It is important to note that photogrammetry will provide topographic information in sparsely forested areas or forested areas that do not have dense cover.
The impact of UAV LIDAR Canopy on grasslands is being investigated. You will notice that the light green and yellowish areas are significantly above the surface of the DEM. This indicates that the laser did not penetrate the vegetation to reach the ground. While the DEM isn't perfect, it gives us a better land area than just using the minimum value.
There are ways to avoid these discrepancies, but that is not our focus today. The average loss of height of UAV LIDAR at the tops of peaks exceeded 0.30 m, and the average relative height loss exceeded 49%, compared to a value of 0.03 m and 6% at the bottom of canopies. The loss of LIDAR information from UAVs in the upper part of canopy had a much greater influence on estimating structural and functional traits of grasslands than in lower part of canopy. With reduction in information loss in tree crowns, UAV LIDAR can be used to extract structural and functional features from grasslands with an accuracy comparable to TLS.
Among five characteristics of grasslands, aerial biomass was least influenced by loss of LIDAR information from UAVs. However, in grassland ecosystems, it is more likely to be influenced by loss of LIDAR information from UAVs caused by dense vegetation canopies. As an expert in UAV LiDAR technology, I have seen firsthand how this technology can be used to penetrate grass and other vegetation. By using lasers that are able to reach through narrow canopies and bounce off surfaces below them, LiDAR systems are able to collect data on terrain features that would otherwise be hidden from view.
Additionally, LiDAR systems are able to provide more accurate topographic information than photogrammetry in sparsely forested areas or areas with dense cover. The impact of UAV LiDAR Canopy on grasslands has been studied extensively, with results showing that while lasers may not penetrate vegetation to reach the ground, they still provide valuable data on land features. Additionally, it has been found that UAV LiDAR systems have a greater impact on estimating structural and functional traits of grasslands than photogrammetry due to their ability to penetrate through narrow canopies. In conclusion, UAV LiDAR technology is an invaluable tool for penetrating grass and other vegetation in order to collect data on terrain features that would otherwise be hidden from view.
By using lasers that are able to reach through narrow canopies and bounce off surfaces below them, LiDAR systems are able to provide more accurate topographic information than photogrammetry in sparsely forested areas or areas with dense cover.