Case Study: Precision Topographical Survey by Castle Surveys Using the DJI M300 and P1 Camera

Introduction

Castle Surveys continues to lead the way in innovative surveying techniques, consistently adopting the latest technology to ensure precise and reliable outcomes. In a recent project, the company undertook a complex topographical survey, employing advanced drone technology to deliver exceptional accuracy. This case study highlights the methodology and results of the survey, conducted using the DJI M300 drone equipped with the P1 camera, along with strategically placed ground control points (GCPs) and checkpoints. The survey achieved an impressive Root Mean Square Error (RMSE) of just 15mm.

Project Overview

For this project, Castle Surveys was tasked with conducting a detailed topographical survey for a redevelopment site. The area presented various challenges, including varied terrain and a mix of open and obstructed spaces, requiring a highly accurate and efficient approach. To meet these demands, Castle Surveys chose to utilise the DJI M300 drone equipped with a P1 camera, rather than relying on traditional ground-based methods.

Equipment and Methodology

DJI M300 and P1 Camera

The DJI M300 drone is renowned for its versatility and stability, making it ideal for complex survey environments. Paired with the P1 camera, which features a 45-megapixel full-frame sensor, the system was perfectly suited for capturing high-resolution images essential for accurate photogrammetry.

Ground Control Points and Checkpoints

To ensure the highest level of precision, Castle Surveys employed a network of ground control points (GCPs) and checkpoints. These were meticulously measured using traditional surveying equipment and strategically placed throughout the survey area. The GCPs served as fixed reference points to correct and align the drone data accurately.

The GCPs were carefully distributed across different types of terrain, while checkpoints were used to validate the accuracy of the final data. This setup was crucial for ensuring that the drone-captured data would meet the stringent accuracy requirements of the project.

Survey Execution

Favourable weather conditions allowed for multiple uninterrupted flights, each lasting around 15 minutes. The drone was operated at an altitude of 100 metres, striking a balance between high-resolution imagery and efficient coverage.

Data Processing and Analysis

After completing the data collection, the images were processed using advanced photogrammetry software. The GCPs were instrumental in georeferencing the images, aligning them with known coordinates and correcting any distortions due to the terrain or camera lens.

The high-resolution images captured by the P1 camera enabled the creation of a detailed orthomosaic map, a 3D terrain model, and contour lines with an impressive vertical accuracy of 15mm. The accuracy of the final model was validated against the checkpoints, resulting in an RMSE of 15mm, which far exceeded industry standards for high-precision surveys.

Results and Client Benefits

The deliverables included a detailed topographical map, a 3D terrain model, and contour lines, all with a verified RMSE of 15mm. These outputs provided the client with the accurate information needed to proceed confidently with the design and planning phases of their redevelopment project.

By utilising the DJI M300 and P1 camera, supported by the strategically placed GCPs and checkpoints, Castle Surveys was able to deliver high-precision results in a time-efficient manner. The client was particularly impressed with the accuracy and speed of the survey, demonstrating the significant advantages of integrating advanced drone technology into the surveying process.

Conclusion

This successful topographical survey by Castle Surveys highlights the immense potential of drone technology in modern surveying practices. The DJI M300 and P1 camera combination proved to be highly effective, delivering the detailed accuracy required for complex survey tasks. The achieved RMSE of 15mm underscores the precision and reliability of drone-based surveys, especially when complemented by traditional techniques like GCPs and checkpoints.

Castle Surveys' ability to adapt and integrate new technologies ensures they remain at the forefront of the industry, consistently providing clients with accurate, efficient, and cost-effective surveying solutions. This case study exemplifies how drone technology is reshaping the landscape of topographical surveying, offering unparalleled accuracy and efficiency for various projects.