There is a TON of interest throughout the construction industry regarding drones. Drones are a great tool and a low cost way to collect topographic data. Unfortunately, all the hype makes surveying with a drone seem overwhelming, complicated and expensive. At Quantum we subscribe to the K.I.S.S system (Keep, It, Simple, Stupid!) regarding drone data collection. Read on to develop an understanding of the basics of drones and data.
You only need two things to collect good drone data. A GPS base/rover and a drone. That’s it. You don't need to spend a dime on software, sign up for an expensive web based processing service or even buy a high end PC for photogrammetry processing.
The GPS system measures your ground control and check shots. By using the same base/rover setup you have already calibrated for machine control we can be certain that your drone data will line up with your project. RTK/PPK drone systems have been marketed heavily and certainly have their place, but for most contractors it's usually best to start with a less expensive, simpler system (remember, K.I.S.S). The goal is to collect good drone data to help you make management decisions. Not become an expert in operating complex drone systems.
The ONLY time you don't need the GPS system is if your drone data does not need to line up with your machine control model or be repeatable. Often, quick stockpile volume calcs fall in this category. Or maybe if you just need a nice orthophoto to show a developer.
Ground control points should surround the site and be placed on roughly the highest and lowest areas of the project (it's the same general concept as GPS site control layout). Quantum recommends a minimum of five ground control points. Ground control can be marked with a temporary target or even painted. You will use your GPS rover to record the coordinates of the ground control point.
Check out the picture below to see how ground control surrounds this small, but odd-shaped project.
Topo check shots are nearly as important as control. They are simply topo shots you collect roughly between control points and in critical areas. When processing your photos we tell the drone data to line up with your ground control. The check shots are completely independent and allow us to verify that the final surface is accurate and located correctly.
Take a look at the ground control and check shot layout below. Note that most of the red GCP's surround the site and the yellow check shots are roughly between control.
Now, the drone. Many contractors use DJI drone systems. There are plenty of good, even better, drones out there but DJI is a great place to start and meets the cost and accuracy requirements for most civil projects. All the drone has to do is fly over the site and collect overlapping photos at a fixed interval. To program the flight area and photo overlap you can use a free app like DJI Ground Station Pro on an iPad. GS Pro, and other apps like it (maps made easy, pix4d, etc…), allow you to draw a box around the flight area, set your flight parameters then fly an automated mission to collect the data. You don't even need to fly the drone manually if you don't want to. At the bottom of this post is one of our YouTube videos explaining how to set up a flight plan in GS Pro (don't forget to hit the subscribe button!). Flight planning in other apps is similar.
That’s it. You don't need anything else to collect drone data. With the base/rover you already own and an inexpensive drone kit you can capture topo data on any project, whenever you need it.
Now that you have performed a topo with your drone, what do you do with the photos and control data, you ask? That is where Quantum Land Design steps in. You upload your photos and control data to our cloud. We then process your photos to develop a 3D surface and orthographic photo of your site. The data will line up with any previous topos you may have done, your machine control model and any future drone or ground surveys you do. Our technical experts can perform volume calcs, do custom designs or hand over the 3D surface for you to use in whatever software you like. The key here is that you don’t need to learn ANY new software or web applications. The surface we send you will be compatible with whatever takeoff software you use, Carlson, AgTek, Trimble Business Center, Magnet and many others.
Have questions? Just email me or call at 515-505-3510 ex 702.