A Step-by-Step Guide to RTK Drone Mapping

Drone mapping utilizes drones equipped with high-resolution cameras to survey an area and generate accurate geospatial data. The process involves planning a flight mission in specialized software, ensuring full coverage of the target area. The images captured during the flight are stitched together using photogrammetry software to create an orthomosaic map—a detailed, seamless representation of the surveyed area.

For accurate alignment, ground control points (GCPs) are used. These reference points, with known coordinates determined via RTK surveying, help ensure precise positioning within real-world environments.

Essential Equipment for Drone Mapping

A basic RTK drone mapping setup includes:

RTK-enabled drone for accurate aerial mapping

GNSS base station to send real-time corrections

Rover unit (Emlid Reach RS3, Reach RX) for collecting GCPs

4-5 GCPs for accurate alignment and positioning
Pix 4D and Emlid Reach RX Scanning Kit

Photogrammetry software for data processing

The Drone Mapping Workflow

1. Setting Up the Base Station

Upon arrival at the survey site, the first step is setting up the base station to stream RTK corrections to the drone. This is typically done by positioning it over a known control point or establishing one using NTRIP (Network Transport of RTCM via Internet Protocol). Ensuring a stable and accurately measured base position is crucial for high-precision results.

2. Preparing Ground Control Points (GCPs)

GCPs enhance mapping accuracy by serving as georeferenced markers. When setting up GCPs:

Use a bi-pod for survey poles to minimize movement errors
Average GCP positions for 5–10 seconds for optimal accuracy
Ensure visibility with large, high-contrast targets
Evenly distribute GCPs across the site, placing them closer in areas with significant elevation changes
Establish permanent reference points for validation

3. Collecting GCP Positions

GCPs can be measured before or after the flight, ensuring they align with the project’s coordinate system. A rover like the Reach RX or RS2+ is used to capture precise GCP locations.

4. Establishing RTK Connection

The RTK connection between the base and drone must be correctly set up to achieve centimetre-level precision. Options include:

NTRIP Caster: Uses internet-based corrections
Local NTRIP: Provides offline correction data for remote locations

5. Planning the Drone Flight

Drone mission planning involves:

Confirming RTK corrections are received
Defining the survey area with a margin for full coverage
Selecting the drone’s camera model
Choosing oblique mode for 3D mapping
Setting flight altitude and course angles
Configuring image overlap (80% front, 75% side) for optimal data processing

6. Executing the Drone Flight

After final checks, the drone autonomously flies the pre-planned mission, capturing high-resolution images with embedded geolocation data.

7. Data Processing and Model Generation

Once the flight is complete, data processing involves:

Importing drone images into photogrammetry software (e.g., DJI Terra, Pix4D)
Adjusting horizontal and vertical accuracy settings
Importing GCP data for enhanced alignment
Validating model accuracy using checkpoints
After processing, the result is a precise 3D model or orthomosaic map that can be integrated into GIS and CAD software for further analysis.

Choosing the Right RTK Equipment

For professional drone mapping, selecting the appropriate RTK receiver is essential:

Base Stations: Emlid RS2+ or RS3 for high-precision correction data
Rover Units: Reach RX for a compact, easy-to-use GCP collection, or RS3 for rugged fieldwork with LoRa radio support

Conclusion

RTK drone mapping is an essential tool for professionals across various industries. With the right equipment and a systematic approach, surveyors and mapping specialists can achieve highly accurate geospatial data with ease. If you're looking to enhance your drone mapping capabilities, explore Candrone’s selection of RTK solutions today!