Drone mapping 101: a step-by-step guide to aerial surveying with Tim Durham

Many industries use drone photogrammetry—from land surveying and construction to archaeology, real estate, insurance, and forensics. As technology advances, aerial mapping is becoming increasingly affordable and accessible. 

Despite its accessibility, the technology remains a complex field with many nuances. In this blog post, weʼll walk you through the entire RTK drone mapping workflow from scratch, using an example from Tim Durham, the owner and chief pilot of Midsouth Drone Services and Drone Mapping Tools. 

What is drone mapping?

Drone mapping, or UAV aerial mapping, is a method of collecting geospatial data by using drones or UAVs equipped with high-resolution cameras and GNSS receivers. These drones fly over a defined area, capturing overlapping aerial images that are later stitched together using drone mapping software to create 2D orthomosaics or 3D models.

This technique is widely used in topography, cartography, environmental monitoring, and construction planning. Mapping with drones is faster and often more cost-efficient than traditional land surveying. 

There are several types of drone mapping deliverables depending on the project goals—orthophoto mapping, digital models, multispectral imaging, and more—all suited for different environments and outputs.

Solving real-world challenges with drone mapping

Thanks to its speed, accuracy, and adaptability, drone mapping is now a go-to tool in a wide range of industries. 

In construction, it’s used for tracking site progress, calculating volumes of stockpiled material, and generating cut-and-fill reports to guide earthmoving work. 

Agriculture relies on 2D and 3D drone mapping to monitor crop health, optimize irrigation, and plan planting layouts with precision.

In environmental monitoring, drone mapping technology plays a critical role in observing forest health, tracking erosion patterns, and protecting sensitive ecosystems. 

The mining sector also benefits, using drones to safely inspect hazardous zones, assess blast areas, and build accurate terrain models for planning.

Insurance and real estate professionals use drone mapping services to assess property damage, generate high-resolution visuals for listings, and document site conditions. 

The versatility of UAV aerial mapping makes it a valuable asset across nearly every sector that relies on spatial awareness and precise geospatial data.

How does drone mapping work?

Drone mapping works by capturing a series of overlapping aerial images that are later processed into an accurate map or 3D model. To do this, the drone follows a pre-planned flight path, flying in a grid-like pattern to ensure complete coverage of the area. The onboard camera takes high-resolution photos at regular intervals. These photos typically overlap by 70–80%, which allows photogrammetry software to stitch them together and reconstruct the terrain in detail.

To ensure precise alignment, you also need a minimum of 5 ground control points (GCPs), and more for larger or more complex areas. GCPs are clearly marked locations on the ground with precisely known coordinates, determined through RTK (Real-Time Kinematic) surveying either before or after the drone flight. After the flight, the coordinates of the GCPs are used during processing to align the aerial data with real-world locations.

These targets should contrast strongly with their surroundings and be large enough to be visible in the drone’s images—typically at least 75 cm (18 in) wide. Acting as fixed reference points, GCPs play a crucial role in minimizing distortions, correcting positioning errors, and ensuring the final map is accurate enough for applications like surveying, construction, or agriculture planning.

Once the data is collected, photogrammetry software analyzes the overlapping images, matches common features, and triangulates their position. Combined with the GCPs, this process produces georeferenced orthomosaics, elevation models, or 3D reconstructions that can be used for measuring distances, assessing volumes, or planning operations.

Requirements for setting up the drone mission

A basic setup for a drone mapping mission usually includes:

• A base station to send corrections to the RTK drone,
• An RTK drone for aerial mapping,
• A rover unit for collecting GCPs,
• 4-5 ground control points (GCPs) to accurately align and position the map within the environment. Larger areas require more.
• Drone mission planning and flight control software.
• Photogrammetry software for processing digital images and generating 3D spatial data.

However, every project has its unique requirements, demanding different setups. Tim’s setup includes an Emlid RS2+ base to send corrections to his DJI Matrice 300 RTK drone with a P1 camera, a Reach RX rover to capture GCPs, several GCPs, DJI flight planning software, DJI Terra photogrammetry software. You can learn more about Reach integration with DJI RTK drones in our documentation.

Drone mapping in action

Now, let’s go over the entire process from scratch using Tim’s example. Tim’s goal was to create a 3D model of an old barn scheduled for demolition, preserving its structure digitally. For this, he uses the Emlid RS2+ base, Reach RX rover, and a DJI Matrice 300 RTK drone equipped with a P1 camera. While drone mapping involves additional steps, the core process remains the same for all aerial mapping activities.

Setting up the base

Upon arriving on-site, your first task is to set up the base that will stream corrections to the drone. For precise georeferenced data, which is linked to a specific location on Earth using a coordinate system, you need to position it over a known point. This may be done using an already established control point or, in most cases, setting it up yourself. To learn more about the base setup methods, check out the guides in our online documentation.

Tim sets up his Reach RS2+ base as a rover to receive corrections from a Mississippi CORS network (NTRIP) and then collects the point using the averaging option for 8 minutes. This control point provides fixed ground coordinates, linking aerial images to real-world locations. This step ensures the map aligns accurately with other geospatial data, ready for integration into mapping and GIS systems.

Preparing GCPs

While collecting the control point, Tim sets up several GCPs around the barn area. These targets, contrasting with the surrounding area, will stand out in the drone’s images and help accurately align and position the map within the real-world environment. For targets placed around vehicles or human activity, Tim paints small marks on the ground by the GCP corner to verify they have not been moved since their placement.

Steps to place GCPs

To achieve high accuracy and seamless map alignment, you should keep the following in mind when placing GCPs:

• Use a bi-pod for a survey pole: Even the slightest touch of the survey pole can cause the rover to move while recording the point’s coordinates. It’s better to use a bi-pod to ensure the rover stays still while recording the point. Alternatively, you can use Reach RS3 with the tilt compensation feature and let it eliminate such errors.
• Take 5–10 seconds when collecting the point: When you record the coordinates of your GCPs, average their positions for 5–10 seconds. Reach receivers provide a reliable fix solution, but it’s better to ensure that the FIX solution is updated accurately.
• Use enough GCPs: Depending on the survey area size, plan for about 5 GCPs.
• Ensure visibility: GCPs should be large and highly visible, contrasting with their surroundings. Each GCP’s center should also be clearly marked.
• Distribute GCPs evenly: Space GCPs across the area. For terrain with elevation changes of 50–100 meters, place GCPs closer together to account for variations. If using 5 points, place one at each corner and one in the center.
• Create your own checkpoints on-site: Besides the GCPs, it is also useful to check your data with some permanent distinguishing features of the site. It can be an easily seen corner of the pavement, or something else. If there are no “natural” distinguishing features on the site, create your own. For example, it could be a rebar that’s been pounded into the ground to act as a control point for check-in and check-out shots. Painting the GCP or сheckpoint on the ground or pavement is an efficient way to create a target without having to return later and pick it up.

Сollecting GCPs positions

The next step is collecting GCPs positions—this can be done either before or after the flight. The key is to gather them in the correct coordinate system and with a FIX solution. They will be needed for data processing in the photogrammetry software later. Tim completes this step post-flight using the Reach RX receiving corrections from the Mississippi corrections network. You can also do the same with Reach RS2+. Check out the Preparing ground control points for PPK UAV mapping guide to learn more about GCPs placement and measurement.

Setting up an RTK connection between the base and the drone

To capture imagery with centimeter-level precision, you need to establish an RTK connection between the base and the drone. Tim uses a manually defined point as his base’s position, which he previously collected using the averaging feature, and emphasizes the importance of double-checking it before the flight. After that, he sets up the correction link between the base and rover via Emlid Caster for accurate positioning.

When using an RTK connection through Emlid Caster, make sure there’s reliable cell service in the area. If cell service isn’t available, consider using a local NTRIP option as an alternative.

Both ways are described in the DJI RTK drone and Reach RS2/RS2+ base integration guide.

Setting up drone flight

The next step is configuring your drone’s settings in drone mission and control software. Tim does the following:

1. Double-checks that his DJI drone is receiving corrections from the Reach RS2+ through Emlid Caster.
2. Sets up a mapping mission by defining the area he wants to cover with an added margin to ensure the ground control points are included.
3. Selects his drone’s camera model.
4. Selects the oblique collection mode for 3D mapping. In this mode, the drone captures images at an angle, unlike NADIR images, where the camera points straight down.
5. Sets the flight altitude and angle course.
6. Sets the photo overlaps: front overlap to 80% and the side overlap to 75%. The front and side overlaps determine how much each photo overlaps with the next during post-processing. Increasing the side overlap improves stitching precision by capturing more matching features but reduces the area covered in a single flight. Increasing the front overlap speeds up photo capture but may eventually reach the camera’s technical limits.

All these settings are adjusted based on the specific conditions of the flight mission.

Now, everything is ready for the flight. Tim performs two flights—one following the configured mission and another manually, descending from the set altitude to a lower level to have a good representation of the barn facade features and details.

Processing the data

As a result of his fieldwork, Tim has the following data to process back in the office, which will later become a 3D model of the barn and the surrounding area:

• Set of images with EXIF data from his DJI drone
• CSV file with the GCP positions

One of the most important things to keep in mind when post-processing the resulting data is setting up the correct coordinate system for the project. The choice should be based on the base’s coordinate system and considered both when importing images and GCPs positions.

Tim imports the images with EXIF data from his drone into DJI Terra for photogrammetric processing. Then, to improve the project’s overall accuracy, he exports the EXIF data and edits the horizontal and vertical accuracy values to 1 meter in Excel, ensuring the software prioritizes control point accuracy over image data. While this adjustment isn’t standard, it’s a common practice in photogrammetry to ensure that control points guide the processing, resulting in better overall accuracy.

Optimizing precision with GCP data

Afterward, he uploads the corrected EXIF data and imports the GCP data collected with Reach RX, which will take precedence over the EXIF data to further enhance the project’s accuracy. When working with GCPs, Tim ensures their positions are recorded accurately and, if necessary, optimizes them using DJI Terra’s tools. The GCPs are then matched with the data in the images and used to make fine adjustments, aligning the image coordinates with the ground control points. Additionally, Tim uses a checkpoint, which is easily seen as a fixed object in the surveyed area, to visually monitor for any distortion when getting the ready model.

To ensure that the whole area is covered, Tim also uploads a KML file with the surveyed region of interest to filter out any excess data, which he created while collecting GCPs with Reach RX.

Finally, DJI Modify renders the 3D model with detailed, immersive views that you can easily share online.

Video tutorial by Tim Durham

If you prefer video, check out Tim’s tutorial, where he breaks down the entire 3D mapping process step-by-step.

How accurate is drone mapping?

Once you collect and process all your data, how accurate can your project really be?

Under the right conditions, drone mapping can achieve horizontal accuracy within 2–3 centimeters and vertical accuracy within about 5 centimeters. This level of precision is more than sufficient for most commercial applications, from mapping land parcels to laying out foundations on a construction site.

Achieving such accuracy depends on several factors: incorporating well-measured ground control points, maintaining consistent flight parameters, and applying proper post-processing workflows. High image overlap and stable flight altitude also contribute to sharp, distortion-free results.

When you use the right equipment and follow proper workflows, drone mapping delivers data that’s both visually impressive and accurate enough for engineering-grade work.

Additional benefits of using drones for surveying and mapping

Beyond accuracy, drone mapping offers a host of practical benefits that have made it indispensable for modern surveying and mapping teams. 

First and foremost is efficiency. What once took days or even weeks on foot can now be surveyed in hours. This rapid data collection leads to faster decision-making on-site.

Drone mapping is also cost-effective. It reduces the need for large field crews and repeat site visits. 

Versatility is key, too. Drones can be used to map everything from flat fields to complex building facades, steep slopes, or dense vegetation. 

Drones improve safety by keeping teams away from hazardous terrain, unstable sites, and traffic.

In short, drone mapping transforms workflows—making data collection smarter, safer, and easier to scale.

Limitations of drone mapping

Despite its many strengths, drone mapping isn’t without limitations. 

Weather can be a major factor—drones are sensitive to wind, rain, and poor visibility, which can delay flights or impact data quality.

Battery life is another constraint. Most commercial drones can only fly for 20 to 40 minutes per charge, meaning larger areas may require multiple flights and careful energy planning. 

Airspace regulations also play a critical role in drone mapping. Depending on your country or region, you may need specific certifications, operational permits, or flight approvals—especially when flying near airports, military zones, or densely populated urban areas. These rules ensure both airspace safety and privacy.

In addition to restricted zones, some areas are completely off-limits for drone operations. These typically include national security facilities, correctional institutions, and other sensitive infrastructure. It’s important to check local aviation authority maps or databases before each flight to ensure compliance and avoid penalties.

In many places, regulations also mandate visual line-of-sight (VLOS) operations, which can limit how far the drone can travel from the pilot. 

Lastly, processing drone data—especially high-resolution 3D drone mapping—requires powerful hardware and a working knowledge of drone mapping software. Managing large datasets can be demanding if your systems aren’t up to the task.

Still, these challenges are manageable with good planning and the right tools. For most teams, the advantages of drone mapping far outweigh the constraints, making it a dependable solution for aerial surveying and spatial data collection.

Which Reach receivers to use for drone mapping

Despite these challenges, one of the biggest factors in overcoming drone mapping limitations is using reliable positioning equipment. If you’re capturing GCPs or providing real-time corrections to your drone, high-quality GNSS receivers ensure the accuracy and consistency of your data. That’s where Emlid’s Reach receivers come in.

The Reach RS2+ and RS3 are ideal base stations for RTK drones. They support two correction methods: sending NTRIP over the internet via Emlid Caster or using Local NTRIP in Emlid Flow without an internet connection. You can also log raw data as backup and improve results later with post-processing in Emlid Studio.

To collect GCPs, you can use Reach RX or Reach RS3. Reach RX is a perfect choice if you work in an urban area and need something light and compact. It accesses network corrections using the internet connection on your smartphone or tablet so that you can collect ground control points within an instant. With Reach RS3, you can work in any area. It receives corrections from an NTRIP service via LoRa radio and from third-party bases supporting the TrimTalk protocol over the UHF radio. Reach RS3 also offers the tilt compensation feature that simplifies stakeout and provides survey-grade results even in hard-to-reach spots.

Order your Reach from the Emlid online store

Experience the power of Emlid Reach receivers for aerial mapping! Order yours today from the Emlid Store—now available for immediate shipping.