Top 5 Best Practices for Drone Survey Data Collection

Drone surveying is an increasingly popular method of surveying from the air. Engineers and construction companies opt for drone surveying as it is much faster, safer, and cost-efficient. A drone survey needs to be carried out by a highly skilled and fully insured CAA-approved pilot. From accessing remote and not-so-easily accessible locations to sharing comprehensive data from an on-site inspection, drone surveying plays a critical role in the construction industry.

Here are 5 best practices that should be carried out by any professional or an agency for a successful drone survey:

Survey-Grade Accuracy over Convenience

All drones are designed differently and have different purposes. While a survey-grade drone reduces positional errors and is used for more professional work, a commercial drone is used for aesthetic or general purposes.

Accuracy should take priority over convenience, especially when working on tasks where precision is key.

At South West Surveys, we always take note of the client’s requirements and provide a relevant solution based on the accuracy needed for that particular project. For instance, a quarry stockpile measurement has different tolerance levels compared to cadastral surveying.

Implement Ground Control Points and Monitor Checkpoints

Ground Control Points (GCPs) are physical markers with known coordinates placed on the ground throughout the area that needs to be surveyed. The GCPs help anchor aerial data to real-world coordinate systems, ensuring accuracy and safety.

Best practices for GCPs:

• GCPs should be evenly distributed across the corners and the centre of the surveying field.
• Place them in well-lit and stable surfaces. Avoid shadows, moving surfaces, or vegetation.
• Ensure markers are highly visible.

In addition to the GCPs, checkpoints also help in validating data accuracy. Surveyors quantify errors and report confidence levels by monitoring the checkpoints against the processed model. 

Creating a hybrid workflow where RTK/PPK drones are combined with a small number of GCPs helps reduce redundancy and protect against any GPS signal drops.

Ideal Flight Plan & Improved Imaging When Using Drone Surveys

Reliable photogrammetry and consistent coverage can help enhance the accuracy of the surveyed data.

Image overlapping is key in Drone Surveying:

It is recommended to take 70 - 80% of forward overlap and 60 - 70% of side overlap for a seamless data reconstruction. It is best to capture more overlaps as extra data can always be discarded later.

Choose an Ideal Flight Plan For Your Drone Survey:

A consistent altitude and use of terrain flow models can help with height adjustment when surveying uneven terrain.

Nadir flights (vertical view) should be used when working in low muck piles where there is less height variation. Whereas oblique views should be captured in an uneven terrain with rocky slopes, and more angled views.

An ideal flight plan helps reduce the risk of missing any integral data and provides a more reliable dataset for geotechnical analysis.

Adapt Your Drone Survey Plan to Local Conditions

While terrain is important in choosing your flight plan, weather and lighting also have a significant impact on the quality of the processed surveyed data.

Check your drone speed

To reduce motion blur, one should fly the drone as slowly as possible. An image pixel can appear on adjacent pixels due to high speed, resulting in blurred images.

Check the lighting

Planning surveying around solar noon can help reduce shadow creation and glare during surveying. Adjusting the camera’s f-number (aperture) basis the current ecosystem ensures proper exposure throughout, even while working in bright or dim-lit environments. Flying under overcast skies can also help with uniform lighting.

Check the weather

While bright sunny days can cause a lot of glare in imaging, gusts of wind can also hamper the speed and stability of the drone, leading to image blur.

For the accuracy of the survey data, it is important for surveyors to adapt to local conditions and make a plan that is best suitable for obtaining high-quality images.

Validate, Process, and QA Your Data Rigorously

While it may be one of the last steps in creating successful imagery, a 3D model, or any other relevant output, it is also one of the most important to keep in mind.

• Image processing should be done with auto-calibration and not auto-correction, as the latter can distort spatial relationships.
• EXIF (Exchangeable Image Format) data should be kept safe for seamless image processing.
• Align software capabilities with project requirements to ensure efficiency in data collection and accuracy in processed data.
• Establish a formal QA workflow, as a single oversight can lead to inaccuracy in your data.

Drone surveying is a powerful tool available to surveyors, engineers, technicians, and project managers. The success of drone surveying depends on preparation, precision, and performance. It can turn aerial efficiency into survey-grade reliability.

At South West Surveys, we take pride in delivering fast, effective, and highly detailed and accurate surveys across the South West and South Wales. Have a project in mind? Reach out to us today.