LiDAR Surveying Showdown: SLAM or GNSS for Accurate Positioning?

SLAM vs. GNSS in LiDAR Surveying:

Which Positioning Method Fits Your Project?

Overview
In LiDAR surveying, accurate positioning is crucial for generating reliable spatial data. Two core positioning methods—SLAM (Simultaneous Localization and Mapping) and GNSS (Global Navigation Satellite System)—serve different use cases. This article outlines their differences, advantages, and ideal applications to help professionals choose the best fit.

Understanding the Technologies

• SLAM: Builds a map of the environment and localizes the scanner within it using LiDAR, IMUs, and sometimes cameras. Ideal for indoor, underground, or GPS-denied areas.

• GNSS: Uses satellite signals (GPS, GLONASS, Galileo, BeiDou) for real-time global positioning. Best for open, outdoor environments.

Comparison Table: SLAM vs. GNSS in LiDAR Surveying

Strengths and Limitations

SLAM Pros:

• Operates in GNSS-denied environments

• Real-time mapping capability

• High adaptability and mobility

SLAM Cons:

• Accuracy varies with surroundings

• Sensitive to featureless environments

• Demands more processing power

GNSS Pros:

• Consistent centimeter-level accuracy outdoors

• Straightforward data processing

• Suitable for wide-area surveys

GNSS Cons:

• Limited or no signal indoors or in dense areas

• Susceptible to multipath errors (reflections)

• Heavily reliant on weather and satellite availability

Hybrid Approach: Combining SLAM + GNSS
The most robust solutions often integrate both technologies. GNSS provides global positioning; SLAM ensures local detail in signal-poor zones. This hybrid model is ideal for mixed environments—such as urban centers, construction sites, or large-scale facilities—where neither system alone is sufficient.

Conclusion
Choosing between SLAM and GNSS depends on your project’s environment and accuracy requirements. SLAM excels in complex, enclosed areas, while GNSS dominates large, open terrains. When in doubt, a hybrid system delivers the best of both worlds—global reach and local detail.

Optimize your survey workflow by matching the technology to the terrain.

GNSS, which includes systems such as GPS, GLONASS, Galileo, and BeiDou, provides global positioning information by using satellite signals. GNSS is widely used in surveying due to its high accuracy and reliability in open outdoor environments. The system works by receiving signals from multiple satellites and using these signals to calculate precise geographic coordinates. GNSS is well-suited for large-scale surveying projects and applications where high positional accuracy is required over extensive areas.