Drones for Surveying

Improve 3D Accuracy in Drone LiDAR projects with Accuracy Star

New hardware and software from GeoCue enhance accuracy with Drone LiDAR projects.

Accuracy is paramount when it comes to drone LiDAR projects. To ensure precise and reliable results, our sister company, GeoCue, presents the new Accuracy Star, a specially designed ground control target that can be easily installed on your tripod. When used in conjunction with the 3D Accuracy Add-on in LP360, this innovative solution enables automated vertical and horizontal accuracy checks and improvements like never before.

In the video below, Darrick Wagg, Vice President of Customer Success for GeoCue, reviews 3D Accuracy, the new Accuracy Star hardware, and the 3D Accuracy Add-on in LP360.

Versatile and User-Friendly Installation

The Accuracy Star offers flexibility in deployment, allowing you to choose between installing one or multiple units as targets in the flight area. Designed to be set up over known survey nail locations or function as a base station when combined with GNSS technology, this target seamlessly integrates into your existing workflow. It's important to note that the Accuracy Star does not include a tripod or base station, but it is fully compatible with your preferred equipment.

Accuracy Star, from GeoCue, is a target specially designed for drone LiDAR projects to be installed on your tripod. (tripod not included)

Unlocking the Power of 3D Accuracy in LiDAR Applications

Ground Control Points are fixed points with known geodesic coordinates and controlled accuracy and precision. These points can be obtained from the National Geodetic Authority or created by the user. Ground Control Targets, on the other hand, are devices that define a unique center.

In LiDAR applications, GCPs serve two essential purposes. Firstly, they determine the accuracy of the LiDAR point cloud by comparing it with targets of known coordinates. Secondly, GCPs facilitate global alignment of the point cloud, enhancing both precision and accuracy.

Precision improvement is measured by reducing misalignments between lines, while accuracy improvement is achieved by minimizing misalignments between the point cloud and GCPs. By comparing the Computed Ground Control Target (GCT) Center with the GCP coordinates, the deviation from the local point cloud to the GCP at the GCP location can be assessed, enabling computation of the LiDAR point cloud accuracy.

Traditionally, 2D Ground Control Targets like the Checkboard Target or the Concentric Circle have been used. While they yield robust and quantifiable results, they do have some limitations. Estimating the center relies on sampling low and high-intensity (B&W) points over the target. Additionally, determining the Z value requires spatial interpolation in the vicinity of the estimated center.

Classic Ground Control Targets: Checkboard and Concentric Circle

Enhancing Accuracy with the Accuracy Star

This is where the advantages of using 3D accuracy with the Accuracy Star become apparent. The hexagon geometry of the Accuracy Star enables the user to estimate the center based on three to six clusters of points representing the reflectors. Redundancy in the hexagon observation ensures precise and robust center estimation.

The size and separation of the reflectors in the Accuracy Star have been optimized to provide excellent detection capabilities for most UAV LiDAR flight configurations. Furthermore, the target's design ensures unbiased accuracy assessment, thanks to the redundancy provided by the six reflectors. The Z component is derived from the vertical separation of the reflectors from the ground, underscoring the importance of installing the Accuracy Star at the highest possible elevation.

A point cloud with the Accuracy Star

Strategic Placement of GCTs for Optimal Results

To obtain a conservative estimate of accuracy, it is recommended to install Ground Control Targets in locations with higher positioning uncertainty. For example, in long corridor surveys, GCTs should be placed at the beginning and end of the corridor to measure the effect of IMU heading bias along the route, particularly when the UAV is flying at low speeds.

Accuracy assessment can be performed in overlapping areas (intersections between lines), non-overlapping areas (single line), or line by line. Discrepancies between different lines offer valuable insights into local survey accuracy and help identify potential sources of errors specific to certain lines. When conducting multiple flights in the same area on the same day, using the same GCTs for all flights ensures consistency in accuracy evaluation.

Achieving Global and Local Accuracy

For those seeking global accuracy, accuracy assessment and enhancement should be carried out using multiple Accuracy Star units distributed throughout the survey area. On the other hand, if local accuracy is the focus, the Accuracy Star should be placed at the specific location of interest.

Accuracy Star Specifics

What sets the Accuracy Star apart is its ability to provide accurate assessments independent of the underlying terrain. Regardless of whether the area is flat, gently sloping, wet, dry, or exhibits high or low reflectance, the target's reflectors offer consistent and reliable information. The accuracy assessment is solely influenced by flight conditions such as altitude, speed, and motion, which can impact point density.

With the GeoCue Accuracy Star, achieving optimal 3D accuracy in drone LiDAR projects has become a reality. This innovative target, combined with the 3D Accuracy Add-on in LP360, streamlines accuracy checks and improvements, empowering professionals to deliver precise and reliable results. Take your LiDAR projects to new heights with the Accuracy Star from GeoCue.

For more information on the Accuracy Star and 3D Accuracy Add-on, please schedule a time to meet with one of our helpful representatives.