In recent years, drones have transformed how construction and earthworks companies handle their worksites by providing precise and dependable survey data. In this article, we discuss the typical factors that can impact the accuracy of drone data and offer advice to ensure optimal outcomes for your aerial surveys. In this guide, we outline the key factors that may impact the accuracy of drone-derived data and offer practical tips to optimize the outcomes of your aerial surveys.
Impact of Flight Speed
The speed at which your drone moves greatly influences the accuracy of the gathered information. Typically, flying at slower speeds enhances accuracy. To optimize this, ensure you use the highest possible shutter speed and ISO settings on your camera.
Significance of Ground Control Points (GCPs)
Even when using drones equipped with RTK/PPK technology, it is still helpful to use special markers called Ground Control Points (GCPs) in the area being surveyed. These markers have known locations on the ground, and they help ensure that the data from your drone matches up accurately with the real-world coordinates. The use of GCPs can enhance absolute accuracy, reducing measurements from meters to centimeters.
Increase Image Overlap
Image overlap in the context of drone data processing refers to the amount of overlap between consecutive images captured during a drone flight. When a drone captures images for creating maps or 3D models, it is important to have sufficient overlap between images to ensure accurate and reliable results.
For better outcomes, it's important to have a lot of overlap between images. We suggest that the images overlap by at least 70%. This means that, in a drone survey, each photo should include new information for only about one-third of its features.
Be sure to choose the right camera model, and if you can, launch your drone from a high point on your jobsite. Taking off from a lower point might lead to flying too close to the ground over elevated areas, leading to insufficient image overlap, which can affect the quality of your data.
(Source: https://photogrammetrydevelopment.blogspot.com/2015/12/planning-of-aerial-photography-overlaps.html)
Ground Sample Distance (GSD), Resolution, and Accuracy
Ground Sampling Distance (GSD) is essentially how much ground or surface area is represented by a single image taken during a flight. GSD affects the resolution of the data.
A high Ground Sampling Distance (GSD) such as 30 cm per pixel indicates that each pixel in the image represents a larger area on the ground, suggesting that the drone is positioned at a greater distance from the ground. This higher GSD results in reduced resolution of the data. Conversely, a low GSD like 1 cm per pixel means that each pixel in the image captures a smaller area on the ground, implying higher resolution in the data. Lower GSD values are associated with more detailed and finer-grained imagery.
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