Justifying the use of aerial platforms for volumetric surveying by addressing their accuracy, speed, safety, and cost
The use of UAVs (unmanned aerial vehicles) for the purpose of obtaining fast and accurate measurements has risen drastically over the past few years. Until recently, ground surveying was the standard method for determining the volume of mining material stockpiles. However, due to the increased efficiency and safety of aerial surveying; mining appears to be one of many industries to benefit significantly from this burgeoning technology.
Here, we will look into the accuracy, speed, safety, and costs behind using UAVs for surveying stockpiles. It can be concluded that aerial surveys produce results of comparable accuracy; safer, faster, and at a lower cost than traditional ground methods.
Quality results are necessary for widespread adoption of alternate methods to any industrial process. Reports provided by surveyors are critical for the production flow and management of any mine or quarry. Previously, the height of stockpiles has been a well-noted barrier to accurate measurements. UAVs allow surveyors the ability to see from above the stockpiles, “So you have a more holistic view of whatever the target inventory you try to measure,” according to an interview in Commercial UAV News.
In case studies conducted by industry-leading surveying software provider, Datumate, aerial surveys consistently reported 3 – 5 cm accuracy. When compared to traditional ground methods, a report published by Underhill Geomatics, Ltd. concludes, “That the UAV photogrammetric approach is, at the very least, equivalent in accuracy to GNSS RTK surveys at the scale of photography observed.”
Increased surveying speed gives way to more frequent measurements. This provides quarry managers time-specific information necessary to make cost-saving decisions. In 2011, Timothy Troy of Rock Products News pointed out that, “Measuring stockpiles has in the past been speculative, time-consuming and difficult.” The time-saving advantages of aerial surveying comes in two forms; both the gathering and processing of measurements.
Deploying UAVs for volumetric surveying grants the surveyor the ability to cover a greater area than what can be achieved in the same amount of time setting up ground laser stations. Additional speed is achieved in processing and reporting the results. For example, using DatGram3D, a software program offered by Datumate, thousands of topographic points can be achieved with a relatively small number of aerial photos.
Simply put, aerial surveying reduces the necessity to navigate the stockpile and quarry area by foot. Keeping the surveyor on low, sure ground is a significant advantage of the aerial method of stockpile measurement.
The cost of UAVs capable of accurate volumetric photogrammetry ranges from around $1,000, such as the DJI Phantom 4, to $50,000 for the Trimble ZX5. As UAV technology has rapidly improved over the past few years, surveyors have enjoyed a reduction in their overhead equipment costs. This is especially significant in comparison to the equipment used in traditional ground surveying methods.
With improved speed and safety over ground surveying, and in addition to lower associated equipment costs, the accuracy achieved through aerial surveying is considered suitable for widespread deployment. It is widely agreed that aerial surveying of mining materials will continue to be the preferred method for stockpile volumetric measurement.