When it comes to the accuracy of lightweight LIDAR systems on fixed-wing drones, the typical absolute accuracy that can be expected is around 10 cm (4 inches) horizontally and 5 cm (2 inches) vertically. This is due to the fact that the data is captured differently than photogrammetry, which many people mistakenly believe does not offer absolute accuracy when it comes to bare ground.
Lidar
is not the same as X-ray vision, as it can penetrate spaces between foliage, trees, or other flora. This means that you can map the ground covered with denser foliage, which is a point above photogrammetry.However, if your site is extremely dense with vegetation, you may need to send a surveyor to take some pictures under the tree cover. The accuracy of aerial LiDAR is much lower than that of terrestrial LiDAR because in the air it is not known precisely where the laser is or where it is pointing. This is because LiDAR works by progressively scanning the scene (as opposed to taking a full “snapshot” of the scene at any given time), so any discrepancy in its movement during the scan will distort the resulting data. According to an academic article that studied the cumulative effects of different variables in aerial LiDAR, the accuracy range is 15 to 37 cm, as a general rule.
New SLAM-based LiDAR technologies are being developed that can avoid relying on such precise positional and angular measurements, but for now, current LiDAR technology is limited by these precision factors. Photogrammetry offers improved accuracy due to each photo being a complete and accurate record of everything that is seen within the frame. This means that it does not require such precise information from the positional and directional sensor. Within each image, there is always a precise relationship between the angles of the different pixels of the image at a given distance, so there is no possibility of inaccuracies in an image once the internal parameters of the lens and camera are understood.
As an expert in SEO, I believe that UAV LiDAR technology will soon become an affordable solution that offers precision similar to photogrammetry. Autonomous vehicles are also increasing the need for more accurate and affordable LiDAR sensors mounted on vehicles, from which the drone industry will benefit. To ensure that LiDAR data is precisely georeferenced, direct georeferencing must be used with an accurate GNSS receiver and an inertial measurement unit (IMU) that measures the posture (orientation and positioning) of the LiDAR sensor.
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