Client: Hanson Aggregates
Location: Irwindale, CA
For this project we were afforded the opportunity by one of our clients to provide a verification survey and prepare stockpile volume calculations for an aggregates stockpile that was incomplete in the data set returned from a mobile lidar survey that had recently been conducted. Early in our planning we recognized the opportunity to both deploy our UAV in conducting the field work and to perform a comparison between data collected using terrestrial laser scanning and data generated from aerial photogrammetry (obtained using our in-house UAV system).
In addition to preparing volume calculation for the approximately 50,000 cubic yard stockpile (see photo below) that was requested by the client, we selected a relatively small stockpile (about 6,000 cubic yards) to perform the comparison survey. As part of the data comparison process, we set numerous control check points that were surveyed with a total station and RTK GPS. These control points were then captured as part of the laser scanning control and as control targets visible in the UAV photography.
The data was reviewed, analyzed and processed back in the office, then we generated a TIN surface of the stockpile from each data set. When we compared the final results of the stockpile volumes we realized that the results obtained from the photogrammetry were superior to that obtained from laser scanning. It was apparent that the aerial view provided a more complete surface, revealing irregularities covering the top surface of the stockpile that could not be captured by the laser scanner that was setup on the ground. Utilizing UAV’s for stockpile volume calculation projects is quickly becoming the industry standard. This approach results in obtaining more complete data in a shorter amount of time as compared to terrestrial scanning, mobile lidar or other more traditional methods.