Table of Contents

• Basics of RTK surveying and laser scanner surveying

• Accuracy comparison: which is more precise?

• Cost comparison: initial and operating costs

• Work efficiency comparison (speed and processing time)

• Ease of handling equipment

• Summary: choose according to the application

• A new option ideal for simple surveying: LRTK

• FAQ

In civil engineering and construction sites, two surveying technologies have attracted major attention in recent years: RTK (real-time kinematic) positioning and 3D laser scanners. Both enable high-precision measurement, but their approaches and strengths differ considerably. Field personnel often struggle with the question “Which should we adopt?” from the perspectives of accuracy, cost, work speed, and ease of equipment handling. This article compares RTK and laser scanners in civil and construction fields, explaining the advantages and disadvantages of each in detail. Considering the latest technological trends, we discuss in which situations each method becomes advantageous, to help you choose the most suitable surveying technique for your site.

Basics of RTK surveying and laser scanner surveying

First, let’s summarize the basic mechanisms and characteristics of RTK and laser scanners.

• RTK surveying (GNSS positioning) – RTK stands for real-time kinematic and refers to high-precision GNSS (satellite positioning) technology. By comparing the GPS observation data of the rover (mobile unit) and the base station in real time and correcting errors, RTK enables centimeter-level positioning. Traditionally, dedicated high-performance receivers were required, but if you install a base station or connect to an existing active control point network, you can obtain high-precision coordinates on site immediately. However, RTK surveying primarily yields coordinate data for individual points, so to capture the overall surface shape you must measure many points or combine RTK with other methods.

• Laser scanner surveying – A 3D surveying method using laser scanners (LiDAR). The instrument emits laser beams and analyzes the reflected light from targets to acquire countless distance points (point cloud data). A single scan can measure the surrounding terrain and structures as surfaces, and a major advantage is the ability to record shapes in 3D down to fine details. For terrestrial laser scanners, the device can be mounted on a tripod and scan 360 degrees in a short time, acquiring data in the order of millions of points at once. However, the acquired data are basically shape data (a set of coordinates); some models can add photographic color information, but in many cases color is not included. The large, expensive equipment and the data processing effort (discussed later) are also disadvantages.

Now let’s compare these two methods concretely in terms of accuracy, cost, work efficiency, and ease of handling.

Accuracy comparison: which is more precise?

Accuracy is one of the most important points in surveying. RTK and laser scanners both claim high precision, but by nature they excel in different types of accuracy.

RTK surveying accuracy: With RTK-GNSS surveying, if operated properly you can generally obtain position coordinates with errors within a few centimeters. On planar positions, about 2–3 cm (0.8–1.2 in) is typical, and in elevation you can often get accuracy within about 5 cm (2.0 in); under favorable conditions of baseline length and satellite geometry, accuracy can reach the 1 cm range (about 0.4 in). This is a dramatic improvement over standalone positioning (errors of several meters) and meets the accuracy required for many civil construction tasks such as site surveying, setting out batter boards, and as-built control. However, because RTK measures points one by one, it is not well suited for applications that require capturing the entire ground surface in detail. To grasp fine terrain undulations you must observe many closely spaced points, and in terms of point density RTK cannot match a laser scanner.

Laser scanner accuracy: Laser surveying’s strength is that it can measure object shapes with millimeter-level precision. High-performance terrestrial laser scanners can measure at close range with errors on the order of a few millimeters, and even for point clouds of over a million points they can produce highly reproducible, precise 3D models. Because a laser rangefinder measures distance directly to targets, scale errors are unlikely, and scanners tend to excel particularly in vertical accuracy. Since a single scan provides surface point cloud data, minute rock irregularities and structural displacements can be detected with high resolution. However, to improve the absolute accuracy of a laser scanner (i.e., positional accuracy in a survey coordinate system), it is necessary to accurately determine the instrument’s position and orientation or to constrain point clouds to known reference points when merging multiple scans. A single scanner measurement may result in the entire point cloud being offset by several centimeters due to positioning error. Therefore, in practice it is common to align the point cloud to known points measured by RTK or total station after scanning to place the model correctly in the coordinate system.

Summary on accuracy: Looking at standalone capabilities, laser scanners win for local shape-detail accuracy. High-density point cloud data that allow measurements anywhere afterward excel in both accuracy and information content. On the other hand, RTK also meets the accuracy required in construction surveying (tolerances for elevation and planar position in leveling and the like), and in terms of absolute positional correctness over wide areas it is practically sufficient. Another advantage of RTK is that the obtained coordinates are immediately in a known coordinate system and can be used directly in design drawings or GIS without additional processing. Overall, the rule of thumb is: use laser scanners when you need to know shapes down to millimeter-level deviations, and use RTK when centimeter-level positional accuracy suffices or for control point surveying.

Cost comparison: initial and operating costs

Next is a comparison of costs. Let’s look at the initial equipment investment and the operating expenses.

Initial costs: When purchasing dedicated equipment, laser scanner adoption is generally overwhelmingly more expensive than RTK equipment. Prices for high-performance 3D laser scanners vary by model but are often several million yen up to over ten million yen. Including required software and options (tripods, targets, batteries, etc.) demands a substantial initial investment. On the other hand, GNSS receivers and rover sets required for RTK surveying used to cost several million yen, but recently prices have fallen. Simple standalone RTK receivers can now be obtained from several hundred thousand yen upward, and you can start inexpensively by using public correction services (RTK information from active control points) instead of setting up your own base station. New products that combine smartphones with compact GNSS units are offered at much lower price points than traditional dedicated equipment, making adoption feasible even for small contractors.

Operating costs: There are also differences in post-purchase maintenance. Laser scanners, as precision instruments, require regular calibration and maintenance, which entail costs and downtime. Ongoing costs include software license fees, the need for high-spec PCs, equipment insurance, and operator training. RTK equipment incurs maintenance and communication costs (for correction data transmission or service fees), but the hardware tends to be relatively rugged and can be used for long periods if power is managed. Basic positioning apps are often inexpensive, and there are free services or integration options with existing civil ICT systems. Overall, laser scanners have higher maintenance and management costs due to being advanced precision instruments, while RTK’s simpler equipment and software typically mean lower running costs.

Outsourcing costs: If you outsource surveying instead of purchasing equipment, laser scanner surveys generally cost more than RTK surveys. Large-scale as-built surveys using laser point clouds can result in estimates of several million yen, and costs can be more than double those of RTK-based single-point surveys or small-scale site surveys calculated on a labor-cost basis. Outsourced costs depend on site conditions and required accuracy. For instance, if you want high-precision surveying of a wide area in a short time, there are fewer vendors capable of laser or drone surveys, and prices tend to be high. For simple surveys, however, cheaper services are available. In any case, if you frequently need surveys, it can be more economical in the long run to purchase equipment and bring work in-house rather than repeatedly outsourcing; you should decide based on your company’s frequency of use.

Work efficiency comparison (speed and processing time)

On-site work speed, required personnel, and post-processing time differ significantly between RTK and laser scanners. Let’s compare the workflows.

Time required for field measurement: For measuring wide areas, laser scanner surveys generally enable faster acquisition of large amounts of data than RTK. For example, surveying a several-hectare development site by taking points with a total station may take several days, whereas a terrestrial laser scanner can complete the job in about one to two days by moving the tripod a few times. Since the scanner records hundreds of thousands of points per scan, the advantage grows with area. RTK surveying can be conducted by a single person, but because it measures points one by one, raising point density for detailed measurements takes time. However, for small areas or surveys limited to specific points, the situation is different: for small-scale elevation surveys of residential lots or measurements of only the key points of a structure, RTK can measure the required points in minutes and be more efficient than preparing and starting a laser scan. In short, RTK tends to be faster for small projects, and laser scanners tend to be faster for large projects.

Required personnel: Both RTK and laser scanners can generally be operated by one person on site. Traditional optical surveying (total station or level) required two-person teams, but GNSS rovers and automatic-rotation laser scanners often eliminate the need for an assistant, reducing labor costs. However, for laser scanners there is equipment transport and tripod setup, and because the gear has some weight, having auxiliary staff can make long operations safer and more efficient. RTK surveying, which involves carrying a pole with a receiver while walking, is highly mobile and manageable by one person. In terms of on-site mobility, RTK has the edge.

Data processing and time to results: Post-survey workflows also differ. With RTK, coordinates obtained on site are immediately usable. Latitude/longitude or planar coordinates of measured points are available in real time, so recorded values can be reflected in drawings or checked against design data immediately. Post-processing, if required, usually involves minor tasks such as datum transformation or averaging. By contrast, laser scanning requires organizing and analyzing large point cloud datasets. After scanning, point clouds from each setup must be aligned (registered) with dedicated software, noise points removed, and meshes or cross-sections created as needed. This point cloud processing may require a high-performance PC and can take from hours to days depending on data volume. Although automation and cloud services have sped things up recently, the time from field measurement to final deliverables tends to be longer for laser surveying. When you need same-day results, RTK’s agility usually wins.

Ease of handling equipment comparison

Ease of operation and handling skills required are important for deploying technology on site. RTK and laser scanners differ substantially in required skills and learning curve.

Laser scanner operability: Laser scanners are high-functionality measurement devices and tend to require specialized knowledge and skills to operate. From device settings (resolution, range selection, scan parameters) to post-processing of point clouds, mastering the entire workflow takes training. Handling point cloud software and multi-scan registration methods (target placement or feature matching) are areas that require specialized training. The equipment is also heavy and delicate, so careful handling is needed during transport and setup. Repositioning a tripod across uneven terrain can be physically demanding. Planning is also necessary to ensure coverage and avoid blind spots, so laser scanners are not something anyone can just use on a whim. That said, device automation has advanced and many scanners can perform a 360-degree scan with the push of a button, and tablet-based interfaces simplify scan control. Still, the high barrier to full proficiency makes laser scanner surveying a technology that suits some sites more than others.

RTK operability: RTK surveying used to require base station setup and radio settings, but today very simple user interfaces have been developed. Once the rover can receive signals on site and you start the positioning via a controller (tablets and smartphone apps are common), you only need to record each point you want to measure. Staff with limited surveying experience can learn basic GNSS knowledge and operational procedures and become competent quickly. Smartphone-compatible RTK products allow point recording by tapping a screen, enabling even non-surveyors to operate them intuitively. The system configuration is simple — a pole-mounted receiver and a communication terminal (smartphone, etc.) are often sufficient — so there is no complexity of operating multiple devices simultaneously. In terms of ease and casual usability on site, RTK wins: it integrates smoothly into routine surveying tasks.

Summary: choose according to the application

The question “Which is more advantageous in civil engineering and construction, RTK or laser scanners?” has no one-size-fits-all answer. It is important to choose depending on site needs. If you prioritize cost and ease of operation, adopting RTK surveying first is a reasonable choice. RTK is nimble, requires a relatively low initial investment, and performs well for routine as-built checks, setting out, and positioning foundations. Conversely, for projects that require millimeter-level shape capture or detailed 3D records of complex structures, laser scanners are indispensable. Though laser scanners are expensive and involve heavy data processing, the value of the resulting point cloud data can far exceed what conventional methods provide. The key is to select a method that is necessary and sufficient given your company’s work content, budget, and required accuracy, using the comparison points in this article as a reference. Combining both methods can also be effective: for example, using known points measured by RTK to georeference a laser-scanned point cloud, or handling routine work with RTK while outsourcing laser scans only for critical areas. Choosing the surveying technology that best fits the site’s purpose will yield cost-effective, high-quality outcomes.

A new option ideal for simple surveying: LRTK

Finally, let’s touch on the emerging technology “LRTK.” This is an innovative approach that makes RTK even more accessible — *Light RTK* in effect — characterized by ease of use. Specifically, by simply attaching a compact RTK-GNSS receiver to a smartphone, anyone can perform centimeter-level positioning. LRTK does not require specialized surveying equipment or complex setup, so supervisors or construction managers can perform high-precision surveys on the spot. The price point of such devices is dramatically lower than traditional surveying instruments, and because a personal smartphone serves as the survey terminal, single-user operation becomes realistic. With simple operation — for example, following on-screen prompts and pressing a button to complete measurement and recording — LRTK enables measurements without specialist knowledge. This solves problems like “I can’t get surveying done when I need it because equipment is limited” or “scheduling is difficult because we rely on skilled surveyors.”

LRTK can be seen as the next-generation smart surveying that combines RTK positioning accuracy with the convenience of laser scanning. By linking with smartphone cameras and sensors, simple 3D data acquisition is also possible, and there are reports of obtaining sufficiently accurate point clouds and photo records in short timeframes. The technology fits with the Ministry of Land, Infrastructure, Transport and Tourism’s i-Construction initiative (productivity improvement through ICT) and is expected to support DX (digital transformation) in the construction industry. For needs such as “I don’t need a laser scanner’s precision, but I want easier 3D site records than ordinary RTK,” LRTK is an optimal choice. Going forward, smart surveying technologies like this will be key to balancing efficiency and high precision on site.

FAQ

Q: What is RTK surveying? How is it different from traditional GPS? A: RTK surveying is a high-precision positioning method using GNSS (such as GPS). As the name real-time kinematic implies, RTK corrects position errors in real time by using satellite signals observed simultaneously at a rover and a base station, enabling centimeter-level positioning. Whereas standalone GPS positioning typically yields errors of several meters, RTK provides accuracy on the order of centimeters. In construction, RTK is useful for tasks requiring high accuracy such as setting out batter boards and as-built control.

Q: What are the advantages and disadvantages of 3D laser scanner surveying? A: The biggest advantage of laser scanner surveying is that it acquires massive point cloud data at once and records site shapes in 3D as they are. Because terrain undulations and structural details can be captured to millimeter precision, it is extremely effective for detailed as-built verification and modeling complex shapes. It also allows safe, non-contact measurement of hazardous or hard-to-access areas. Disadvantages include high equipment and software costs and the need for considerable skill and effort in data processing. Specialized processing is required to convert point clouds into drawings and quantities, and training personnel to handle the technology is necessary. The size and handling characteristics of the equipment can also make it impractical for small sites.

Q: Which method is suitable for small sites or simple surveys? A: For simple surveys with few points or for checking elevation and position in confined sites, RTK surveying is often more suitable. RTK is easy to prepare and operate and quickly acquires the coordinates of required points. For example, for elevation surveys within a residential lot or periodic checks of key points during construction, RTK is typically more efficient than bringing out a laser scanner. Conversely, if you need to record the entire shape of a building or survey complex terrain in detail, a laser scanner is appropriate. In short: prioritize RTK for ease of use, and laser scanners for detailed recording. LRTK and similar simplified RTK methods are also emerging, expanding options for simple 3D recording.

Q: Can RTK and laser scanners be used together? A: Yes. Combining both can enhance effectiveness depending on site needs. A typical workflow is to georeference laser-scanned point clouds to known coordinates measured by RTK, giving the point cloud absolute survey coordinates and improving model accuracy. On large sites, you can measure main control points with RTK and fill in detailed areas with laser scanning — an effective division of roles. Integrated smart surveying methods like LRTK, which combine RTK and simple scanning, are also appearing. By combining the strengths of each method, you can achieve surveying with a good balance of efficiency and accuracy. Choose flexibly according to your objectives to realize smarter and more efficient measurements.