UAV Mapping Basics - Fixing Precision in Drone Surveys

Over the last several years, decreasing prices and increasing ease-of-use have brought drone surveying to a wider audience. While it may be simpler than ever to purchase a drone, get it in the air, and capture aerial imagery, there are still a number of hurdles to doing so with precision.

Why is this important and how do you address it? We’ll explain with a common example from an industry we specialize in, construction.

Drone Surveying in Construction

Construction teams do two things to make money: create change and monitor that change. Monitoring change, more commonly referred to as progress tracking, is where UAV surveys offer the most value to construction teams. A construction project can be built perfectly, but without accurate tracking and reporting, money will inevitably be left on the table.

two construction inspectors performing manual inspection

Progress tracking is, frankly, a pain, especially when you want to focus on getting shit done. Unfortunately, it’s also a mission critical task for determining whether a project is on-time, on-budget, and on-plan, and for identifying issues before they become delays or rework. So, construction teams need to accomplish it as efficiently and painlessly as possible to concentrate on what they do best.

From cloud-based software to the Internet of Things, the growth of technology on construction projects has made progress tracking simpler, allowing more workers in the field to capture more information with greater ease. UAVs have made a major impact in this area, improving the speed, quantity, and scope of data collected. However, they’ve also given rise to a new set of issues regarding quality. How do you effectively organize this wealth of information and ensure it's correctly analyzed?

Automating UAV data collection and analysis

Without an automated system to catalogue data, you won’t benefit from any new progress tracking technology, especially drones. That’s the problem we’ve been working on at Unearth, making the explosion in construction tech useful by putting the data it creates to work.

drone pilot flying a drone on a construction site

In regard to UAVs, we designed our OnePlace™ software to get the maximum out of your drone data with the minimum amount of effort. We take all your raw files, blend them into a unified project map, and then give you the tools to find the data relevant to you.

Our entire toolset provides instant insights into everything you capture, and then allows you to further integrate information from other platforms to go even deeper. However, we realized this wasn’t enough. After partnering with several major industry innovators, we saw a common problem, and an opportunity to push our technology even further.

Precision, the Biggest Issue in Drone Surveying

Every contractor we worked with struggled to achieve precision over multiple drone flights. When they tried to align different surveys of the same location, it would be between 5 and 10 feet off - a huge problem if you’re trying to accurately measure change over time and align plans over multiple surveys.

screenshot of blueprint alignment flow in OnePlace™

To solve this issue, these companies turned to more hardware, using ground control points and advanced GPS technology to try and dial-in their precision even more. Unfortunately, these methods still contain error and require significant additional work.

In order to really solve this problem, we needed to figure out how to correct for the hardware’s error using software, and that’s exactly what our new GeoCorrection tool does.

How to solve the drone precision problem with software

Drone maps are created by an algorithm that stitches hundreds or thousands of photos into a single image by matching common features in the pictures and overlapping them. It then takes GPS metadata from each photo to align the image to its real-world location.

However, the process is inherently imprecise; drone GPS modules are only accurate within several feet, and the stitching process relies on best fit approximations. Combined, these two factors always create misalignment between any drone surveys of the same location.

To fix the problem, we created a simple tool that allows you to match common points on drone surveys of the same site. Once you identify a minimum of three common points, our software will use them to align the surveys by correcting the errors from GPS and stitching, giving you the ability to simply and reliably detect change over time for easy automated progress tracking. This creates consistent, precise results with minimal effort - and even allows alignment of previously captured surveys not on our software.

Why Does Precision Matter?

Precision is the foundation of UAV data collection; if it's not rock solid, everything you build on top of it will fail. That's why before you try to use drones to monitor any sort of progress, it's essential you solve the precision problem.

Once you're confident that your surveys are aligned, you open a world of possibilities to measure and track change over time. For example, our new Volume Differentials tool takes full advantage of our GeoCorrection solution by allowing you to mark an area, then easily switch between surveys to see the changes in cut/fill values.

software tool

software tool

Want to try it out for yourself?

See how you can get the maximum value from your drones by making use of our full set of drone-related features.

Unearth's construction software on a desktop and mobile phone
OnePlace for Civil Construction

Interested in drones? Check out our other resources!

How to Get Started with Drones in Construction

Five steps to getting started with drones. Scale them to your needs, get the most value, and avoid unnecessary costs.

Construction Drone Buying Guide

Whether buying your first drone or growing your fleet, we outline how to make sure you get the best drone for the job.

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