Drone Mapping 101: How to Make a Map with Drones, GPS, & RTK

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Mark Wilkerson
Mark Wilkerson

Learn about the different ways you can make a map with a drone, including drones without GPS, with GPS, & with RTK – plus tips & tricks to save time.

Drones seem to be everywhere these days. From individuals flying recreational drones on a beach, to professional photographers getting unique shots for their clients, to public works departments observing potholes in their local community, and everything in between, it’s clear that drones are increasingly valuable tools for a wide variety of applications. Drones are especially useful for mapping, as they have the ability to capture georeferenced images at a large scale. 

This is a really exciting development for the mapping and geospatial industry. Just fifteen years ago, no one believed it was possible or feasible to capture georeferenced imagery in real-time from such a small and accessible device. Sure, a few companies and governments collected imagery data from satellites or airplanes every couple years, but this information was not accessible for the vast majority of people making maps. Plus, it was collected for the locations they deemed important and at the specs that suited their project, not necessarily what individuals needed for their own initiatives.  I know this first hand, as I was one of those engineers looking to scale my mapping projects by capturing my own imagery. I even looked into buying a blimp – but that’s a story for another day.

Regardless, the capabilities we used to dream about are now a reality thanks to rapid innovation in the drone and geospatial industries. While the theory behind the process has remained largely the same at its core, new technology has made it possible to drastically reduce the time and costs associated with drone mapping, and even eliminate some steps altogether. 

It’s never been more exciting to work in the drone or mapping industry!

How to make a map with a drone

Before we dive into the different technical approaches to drone mapping, let’s first review the basic workflow that needs to happen (whether by a human or a machine is up to you, more on that later).

Drone mapping is commonly done using ground control points.

1. Determine your methodology

The goal of any mapmaking and associated data collection is to accurately represent objects and places on Earth’s surface. Drone operators can georeference images during post-processing or in real-time, depending on what technology they are using. 

2. Set up ground control points

If you are planning on georeferencing your image in post-processing, you must set up ground control points (GCPs) before flying your drone. These GCPs will serve as known location points for you to use as you determine the positioning of the imagery you capture. To ensure accuracy of the drone imagery captured, be sure to survey these GCPs using a GNSS system. GCPs can also be helpful to ensure the highest accuracy in your data capture, even if your drone can georeference in real-time.

3. Capture your imagery

Once your GCPs are set up, you can fly your drone and begin collecting data. If your drone is equipped with the right technology, you can automate the flight plan and fly longer distances with less effort. Either way, capturing imagery with your drone is the most important part of this whole process; just make sure you’ve set up GCPs or have a way to georeference the images into meaningful data.

4. Stitch your images together in post-processing

Once you have your imagery captured, you need to relate it all together and locate it on the Earth’s surface. As we mentioned, GCPs will help with georeferencing if your drone doesn’t do that in real-time. But it’s also necessary to relate each image to each other so that you can produce a comprehensive and spatially accurate map. Traditionally, this requires a lot of manual effort to stitch together images, although there are some tools available to streamline this process.

And there you have it! This is a bit of an oversimplification of the drone mapping process, but should give you a good starting point for deciding on your own methodology. The key takeaway here is that you can expect to spend time and resources preparing to fly your drone and then post-processing the information captured. Just how much time and effort you invest will depend on what technology you choose, so let’s dive into that next.

Mapping with a drone without GPS

With all of the innovation that’s taken place in the industry, many consider mapping with a non-GPS enabled drone to be the old school method of mapmaking. However, a lot of mappers and surveyors still use this method. If your drone does not have GPS, you’ll need to closely follow the above process we outlined, and be prepared to spend a big chunk of time both pre-flight and in -post-processing. GCPs will be critical for you to georeference, so make sure to take care setting them up in places you can easily spot in the captured imagery. 

Once your imagery is collected, you’ll need to both georeference and stitch it together to produce a map. This can be very manual and computationally expensive, but is a tried and true method for making a map with images captured by a drone.

Mapping with a drone that has GPS

If your drone is enabled with GPS or another GNSS technology, you won’t need to rely on GCPs to understand where each image is located on Earth’s surface. Instead, the drone will time- and location-stamp each image it captures, logging all the data as it flies. Like we mentioned before, it can’t hurt to have a few GCPs set up just in case, but with this type of drone you can definitely cut back on the amount of time you’re spending before flying. 

Even with GPS-equipped drones, you must still spend time during post-processing to make sure the positioning captured for each image is spatially accurate. To do this, you’ll need to download base station and real-time kinematics (RTK) network data (often from a data warehouse or similar service), which can take hours or days depending on the source of the historic RTK data. With this data, you can correct any GPS inaccuracies your drone might have encountered to make sure your images are georeferenced correctly. Once again, you’ll ultimately need to stitch together the georeferenced images to create a complete map. While this process is slightly less tedious than georeferencing by hand with GCPs, you can still expect to spend a lot of time and resources during post-processing to get the best results.

Mapping with a drone equipped with both GPS & RTK

If you’re looking to eliminate as much time and cost as possible when creating a map with a drone, this method is for you. As with other drones equipped with GPS, you won’t need to spend as much time setting up GCPs prior to flying. Additionally, RTK makes it possible to plan high-precision flight paths so your drone can navigate accurately through the real world without GCPs. 

Perhaps the biggest benefit of this method, however, is that drones enabled with both GPS and RTK can not only instantly georeference each image, but also correct any GPS signal inaccuracies in real-time. With RTK, you won’t need to wait hours for your data to be corrected, but instead can instantly download what you captured and produce a map. Drone operators do  not need to pull GPS corrections data down from a data warehouse, but can instead produce a map with just a laptop. Any image stitching, if even needed, is drastically reduced with RTK

All of this means that mapping using a GPS and RTK-enabled drone will save you the most time and resources as you create your end product, plus provide the most accurate georeferencing for your drone-captured images. And thanks to the rapid innovation in this space over the last decade or so, RTK-enabled drones are now accessible and affordable. 

Top 3 use cases for drone mapping with RTK

That overview of drone mapping methodologies might have left you thinking about the many different ways this technology can be applied in the real world. There’s an infinite number of use cases for drone mapping, but some are more common than others.

Drone mapping with RTK is most helpful when you want to optimize speed and cost without sacrificing accuracy. Post-processing is a full-time job when you consider the time and computational effort required to georeference and stitch imagery, and is just not feasible for all drone mapping use cases. There are also instances where GCPs cannot be placed to aid georeferencing, rendering traditional methods impossible. 

As we mentioned, there are endless ways drones with RTK can enhance mapping workflows. We’ve broken down the top three here, including a real-world example of how RTK-equipped drones are helping one mapping professional 5X his production speed.

Mapping places without GCPs

Ground control points are not a viable option in difficult terrain.

Maps are powerful communication, visualization, and analysis tools for pretty much anything on Earth’s surface. However, not all places are easy to map. This is especially true when making a map that requires georeferencing from GCPs.

GCPs are helpful guides for positioning, but need to be placed on Earth’s surface. Increasingly, maps are being made of places or objects not located directly on the ground, which makes GCPs pretty much useless. Take for example a cell tower; drones can capture imagery from all different angles of the tower, even directly above it. But to understand the spatial reference of the various components of the tower, you cannot rely on GCPs – there’s nowhere to place them. In this instance, RTK-enabled drones will provide the best positioning information for the data you capture.

Site monitoring and damage assessment

RTK enables real time mapping solutions for efficient decision making.

Another situation where drones with RTK provide a lot of value is when you need to access data in real-time. This is common when monitoring the status of a project or producing maps quickly to assess damage in an area. Traditional methods of drone mapping require hours or even days of time spent post-processing, which is much too slow when you are trying to produce a map that shows real-time conditions.

For instance, building or construction management teams may fly a drone over their project site to assess how much progress was made in a given day; if they need to wait a few days to see the map, the information it provides is already stale. Similarly, first responders might fly a drone over an area after a disaster to assess damages and determine where to focus aid efforts. In this example especially, having rapidly and efficiently producing accurate maps is critical.

3D modeling

RTK provides optimal georeferencing enabling 3D modeling.

Developing 3D models from drone imagery is another extremely popular application for RTK. More and more industries are relying on 3D models of buildings, assets, neighborhoods, or even entire cities to better understand the real world and make informed decisions. For these 3D models to be effective, they must be georeferenced like any other map.

Teams that produce 3D models can leverage an RTK-enabled drone to greatly reduce their pre- and post-processing time by eliminating the need to set up GCPs, correct for GPS errors, or spend hours stitching images together. For groups that are performing mapping projects in-house, this means they can get to what matters – the actual analysis – more efficiently. For organizations and individuals that provide 3D modeling services, this increased efficiency means they have better margins per project, and can scale their business by taking on more clients.

Real-world drone mapping example for 3D modeling

To help you see just how helpful drone mapping with RTK can be for scaling operations and reducing manual effort, we’d like to introduce you to Cameron Cone. As a content creator and photogrammetrist, Cameron often uses drones to capture imagery for 3D modeling. Prior to incorporating RTK into his drone mapping workflow, Cameron would spend days just post-processing the data he captured before he could turn it into a georeferenced 3D map. 

Using RTK with his drone to develop a 3D map of a mixed-use real estate development in Austin, Texas, Cameron was able to speed up both production and post-processing by 5X. Read more about Cameron’s experience here.

Power your drone with the most comprehensive RTK network 

Now that you have a deeper understanding of the ways RTK can optimize your drone mapping workflows, you might be looking for where to get started. At Point One, we specialize in providing precision location to developers and drone operators so they can save time and resources without sacrificing the accuracy needed to produce scalable, reliable maps. 

Our Polaris RTK network provides GNSS corrections to drones all over the world, with no personal base station required. We actively manage an expanding network of more than 1,440 global base stations so our users can access GNSS correction data in real-time. With Polaris, drone operators can produce maps with 99% uptime and 100x more accurate spatial alignment than traditional solutions. The best part is, Polaris is affordable and accessible for anyone with a drone to leverage. Simply visit our web store to learn more about pricing and order your dev kit.

We hope this has been an informative article for you as you learn more about drone mapping and the innovative ways our industry is changing. A few years ago, I was pretty disappointed in how difficult it was to buy a blimp to accurately capture imagery at scale, but now I’m glad I’m not stuck with figuring out where to store that thing. Drones take up way less space.

Curious to learn more about RTK for drone mapping? Get in touch with our team of experts

Mark Wilkerson
Mark Wilkerson

Mark is Point One's Product Manager. He's a veteran engineer & technical leader with more than 30 years experience in large, distributed, and embedded applications.

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