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AGTEK Answers Your Drone Questions

Drone Questions

Ready to add a drone to your construction workflow? Drones are fast and effective for accurately validating site conditions, tracking production progress, and providing insights into what work needs to be done versus what has already been completed. They can provide very detailed and accurate data that is far easier and safer to capture than when using conventional surveying techniques. This data allows project managers to monitor their crews, material usage, and machinery performance more effectively, enhancing overall resource management.

In this article, the AGTEK experts break down common questions about using drones on your jobsite.

What's the difference? RTK vs PPK

AGTEK recommends the DJI Mavic 3E RTK drone for most construction projects. This drone is extremely versatile and uses a simple workflow to get accurate, repeatable results every time while being affordably priced.

RTK stands for Real Time Kinematic and PPK stands for Post Processed Kinematic. The main difference is that RTK provides a more precise position during the flight. PPK is not real-time, position is calculated after the drone has captured images, thus being “post-processed”. With PPK, positioning can be up to 10 meters off horizontally and 20 meters vertically by spec. This is why terrain following requires RTK.

RTK provides real-time drone position and correction, with centimeter-level accuracy positioning. This means you get accurate data on the flight controller instantly, which is imperative in construction where real-time information is essential. RTK drones provide a smoother workflow because the real-time data correction avoids the requirement for post-processing, simplifying the data management process. With RTK, you can immediately check if your data meets the accuracy requirements in the field. It leaves no room for surprises.

What equipment does AGTEK’s drone package use?

AGTEK only sells drones with RTK (PPK-capable) antennas. We use the same satellites and drone hardware as other top drone solutions. The corrections used are either from an NTRIP base network or an onsite base station, like what the ground GPS rovers use. The type of correction service used with any drone solution depends on the availability of NTRIP base networks and available cell data in your project area. Generally, the base should be within 15 miles of your position. In the event you don't have cell service or a base network close, you can use an onsite base.

At the end of the workflow, the localization and registration process are done regardless of the way corrections were completed, and this will match the data to your site. An onsite base might be slightly more accurate due to a shorter baseline, but there is more setup and complexity involved. In our experience comparing captures, we've found no real difference.

How accurate is your drone data?

There are a couple of ways to check for accuracy. First, we add in controls, preferably three spots that are relatively flat. As part of the processing, these are used as checkpoints to compare the processed data. In Pix4D, this results in an RMS number that compares the model created (by Pix or other programs) to the surveyed values for consistency. If it's below .1 ft (.03m), then you know that the model is consistent with the control distances to that level.

The second part of our process is to move that consistent model to fit with our survey control horizontally (localize) and then adjust the elevation to match a known surveyed planar area (register).

By using a known area to always match between drone flights, we create a flight-to-flight consistency between surfaces while averaging out the inherent noise. While using the control points allows some averaging out, a bigger area does a better job simply because there's more data to sample.

What’s the difference between aeropoints and fixed control points?

Aeropoints are used as a solution when the contractor cannot capture control points on their site. At AGTEK, we believe they trade perceived simplicity for some limitations. We recommend putting out control on the ground permanently in an undisturbed area. At most, you renew spray paint every month or so. The advantages are:

• They don't move unless something obvious comes and physically moves them.

• Consistency from flight to flight and removing a variable in processing.

• They're laid out with the same GPS equipment you use on the project. This makes keeping the data captured for each flight much easier to match to your project.

• Time savings-you don’t have to set up and pick up targets for each flight

Do we need to identify the flight boundary before arriving on-site to fly the drone?

We start the drone controller in the office and plan our flight location before going into the field. We orient ourselves to the project via maps or Google Earth, though KMZ files from AGTEK can also serve this purpose. If you fly the rough boundary of the site, the process of photogrammetry will capture outside of that boundary in the images. It doesn't require much precision.

The biggest challenge you might face is when mapping from all sources isn't up to date, or there is something such as a solid tree line on the map. This is where Google Earth with AGTEK KMZ files will help clarify. When unsure, you can visit the site with our SmartPlan or SmartDirt apps and drive or capture the corners as a reference.

How is drone data delivered?

AGTEK takes the Pix4D point cloud (or any other sourced point cloud) and loads it into our classification engine, REVEAL, which uses Artificial Intelligence trained on construction data to classify obstructions and let you decide what to keep or delete using a simple, visual interface. REVEAL includes the capability to edit pre-designated classifications, so you can customize your workflow.

How is drone data shared?

Post-flight, we verify the quality and what we want to make available in Gradework, then publish the drone surface and ortho file into our cloud service. This can be viewed in our SmartDirt app, enabling communication between the office and the field. In SmartDirt, users can measure and take notes and pictures for sharing site conditions.

Want to learn more?

Employing drones can revolutionize the way worksites are managed. Now is the time to put the benefits of drone data to work. If you are ready to take your workflow to the next level, have additional questions, or would like more information on our drone solutions, reach out to us at


Want to learn more? Contact us and we will be happy to help.