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Using drones to map field elevation changes

Richard Pickett explains field elevation mapping with drones.

Forrest Laws

May 13, 2021

Can farmers and consultants use unmanned aerial vehicles or drones to help precision-level their fields more efficiently and economically?

The short answer is yes, according to Richard Pickett, owner and chief pilot of P&P Consulting LLC in Jonesboro, Ark. But it comes with some caveats, as Pickett explained during a presentation for this year’s virtual Arkansas Soil and Water Education Conference.

One of those has to do with the slow Internet speeds that farmers often encounter when they try to download information. Another is the sheer volume of data that UAVs can generate when they fly across large acreages.

“My computer system is custom-built by Puget Systems specifically for drone photogammetry,” he said. “That way you can process more data. It’s a very robust, very expensive computer. It’s more effective for me to use a local solution than, say, cloud processing because of my slow Internet speed.”

Pickett began his presentation by displaying the different types of images that can be obtained by flying an unmanned aerial vehicle over a field and with ground equipment using a Trimble Field Level II system.

“These are raw points – neither side, left or right, has been surfaced or interpolated in any software,” said Pickett who first began working with drones during his service as an intelligence analyst with the military from 2006 to 2018. “These are just the raw points that get pulled into the software processor.

“You’ll notice that on the left there is significantly more detail compared to the right because on the left the drone isn’t doing survey swaths. The drone is collecting, based on its camera setup and grid pattern parameters, elevation points across the entire field. On the right we have the traditional ground survey of 40-foot swaths using the Trimble system.”

Pickett, who is also working on bachelor’s and master’s degrees at Arkansas State University, displayed a series of slides explaining the elevation analysis side of what the software and technology can do.

“So this is a 400-acre pivot field with raw elevation data that's been surfaced,” he said. “With the system that I use you can bring this surface elevation data into the software and apply different layers on top of it. You can identify for example, elevation changes from the major ridge down to the low areas of the field.

“Then you can apply different filters to look at the depressions. This gives you an idea of where you're holding water in your field to help you with drainage designs. Another filter you can apply is flow direction, which gives you an idea of how the water flows off your ridges into your drainage areas and ditches and then out of the field.”

When the operator overlays the patterns together, “You're able to really zoom in and understand how the field drains and where the good and bad areas are in terms of where you need to put ditches and where they're not needed.”

From this point Pickett can manually draw in where drainage ditches should go and create guidance lines for Trimble or John Deere software to auto track those lines, “and to where you wouldn't have to eyeball all your ditches in an individual fields prior to planting.”

Using drone elevation data has pros and cons, he said.

“Between my small and fixed wing drones, I can cover from 250 to 1500 acres in a day, or I can cover 100 to 300 acres an hour,” he said. “There's potential to cover more, but that takes waivers from the Federal Aviation Administration. To collect 1,500 acres in a day you’re talking a lot of processing time – maybe 24 or 48 hours before you can get it back to the customer.”

On the other hand, drones can collect data from areas of a field that are too wet for ground equipment. “And they collect data across the whole field – you don’t have to interpolate from swath patterns, he noted.

To watch Pickett’s presentation, visit You can startr watching at the 4:45 mark of the 2021 Arkansas Soil and Water Education Conference.

About the Author(s)

Forrest Laws

Forrest Laws spent 10 years with The Memphis Press-Scimitar before joining Delta Farm Press in 1980. He has written extensively on farm production practices, crop marketing, farm legislation, environmental regulations and alternative energy. He resides in Memphis, Tenn. He served as a missile launch officer in the U.S. Air Force before resuming his career in journalism with The Press-Scimitar.

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