Handheld SLAM (Simultaneous Localization and Mapping) technology has gained increasing attention in recent years. This article explores the advantages and disadvantages of handheld SLAM technology and analyzes whether it could become the next-generation measurement technology.

Advantages of Handheld SLAM

Flexible Measurement

The core advantage of handheld SLAM is its flexibility. The SLAM algorithm enables users to measure while moving, though this does not imply unrestricted movement. Different manufacturers have specific operational rules for their SLAM systems, including walking speed, swing amplitude, special area handling, etc., which require training. Nevertheless, compared to traditional stationary total stations or scanners, handheld SLAM offers greater freedom.

Efficient Operational

Area Handheld SLAM devices typically operate for 10-60 minutes. Within the constraints of manufacturer-defined operational rules, a single measurement can cover 10,000-60,000 square meters, making handheld SLAM one of the fastest measurement methods, second only to airborne systems.

High Point Density

Most handheld SLAM devices use laser SLAM technology, specifically 3D laser SLAM. Leading laser brands like HESAI and VELODYNE have point frequencies of 30-64 million points per second, allowing handheld SLAM to achieve point densities comparable to traditional stationary scanners, with ground point densities reaching 5,000-10,000 points per square meter.

Omnidirectional, No Blind Spots

Handheld SLAM allows for omnidirectional scanning, covering the maximum measurement area. Although measurement angles are limited by the handheld device’s height (usually 1.5-1.8 meters), which may not cover very tall buildings completely, this omnidirectional scanning capability is sufficient for most measurement needs.

Rich Raw Data

Handheld SLAM provides not only XYZ coordinates but also intensity (Intensity), RGB values, and panoramic images. These data enrich the analysis of ground features, assist in attribute judgment, and help with precision checks. Panoramic images also provide a record of the site environment and feature attributes.

Diverse Output

The data from handheld SLAM can be processed into various formats, including point clouds, line maps (such as topographic and floor plans), 3D models, quick reality-based 3D models, and more. This capability to generate multiple outputs from a single measurement avoids redundant measurements and improves efficiency.

Disadvantages of Handheld SLAM

Requires Experience

SLAM technology requires a certain level of experience and training to achieve accurate measurements. Inexperienced operators may produce data with reduced precision due to improper operation techniques. While this is a challenge, the issue is expected to improve as the technology matures and becomes more widely adopted.

Relatively Average

Point Cloud Quality Compared to stationary laser scanners, handheld SLAM's point cloud quality is somewhat inferior. Stationary scanners generally offer higher point density and finer point clouds. Additionally, errors in trajectory calculation during handheld SLAM can affect point cloud data. However, for applications that do not require extremely high precision, the point cloud quality of handheld SLAM is often sufficient.

High Cost

The cost of handheld SLAM devices may be prohibitive for many measurement companies and organizations. Although price can be a barrier, those who find a suitable application or project can still benefit from the value offered by handheld SLAM.

Application Areas

Handheld SLAM technology has a broad range of potential applications, including but not limited to the following areas:

Mining: Measurement of mineral volumes, open-pit and excavation volumes, and 3D models of mines.

Stockpile Measurement: Volume measurement of various stockpiles such as grain, sand, and coal.

Facade Measurement: Suitable for simple facade measurements, particularly in urban renewal projects.

3D Modeling and Reconstruction: Generation of 3D/BIM models, digital archiving, and other related tasks.

Underground Space Measurement: Creation of floor plans and 3D models for underground spaces.

Topographic Map Correction: Useful for correcting small areas of topographic maps.

Other Applications: Includes forestry applications, education, cave surveys, construction completion measurements, and progress monitoring.

The Prospect of Handheld SLAM

In summary, handheld SLAM technology, with its flexibility, efficiency, and diverse output capabilities, shows significant potential to become the next-generation measurement technology. However, challenges related to technology maturity, data precision, and real-time processing need to be addressed. As the technology evolves and application scenarios expand, handheld SLAM is likely to play an important role in the future of measurement.