Comparison of 3D Surveying Methods: Advantages and Disadvantages of Laser Scanners, Drones, Photogrammetry, and LRTK

3D surveying is a technique for collecting shapes of natural terrain, structures, and the like as XYZ three-dimensional coordinate data.

It is used in various fields such as construction sites and civil engineering design, recording archaeological sites, and building 3D data for VR/games. Recently, 3D surveying technologies have advanced, and many methods have developed. This article compares four major 3D surveying methods—"3D laser scanner surveying," "drone surveying," "photogrammetry (photogrammetry)," and "LRTK-based surveying"—explaining each method’s characteristics, advantages and disadvantages, use cases, accuracy, and cost differences. While acknowledging technical complexities, the explanations will be easy to understand for general readers. If diagrams are needed to show shapes or workflows, display "[ Insert figure ]".

3D Laser Scanner Surveying

3D laser scanners emit laser beams from dedicated equipment and detect reflected light from targets to precisely measure distance and position. Since a single measurement can collect tens of millions of points, it obtains "point cloud data" composed of a large number of points. Because coordinates and shapes can be reproduced with high accuracy, this method is useful for construction site surveys, recording ancient ruins, and scenes where detailed measurements are required. [ Insert figure ]

• Advantages: The biggest advantage is obtaining extremely high-precision 3D data in a short time. With proper maintenance, you can capture detailed information down to a few millimeters. At the same time, because it can collect large amounts of points over wide areas per unit time, it enables labor saving and efficiency compared to traditional manual surveying. In other words, it is useful for making detailed architectural models and 3D visualizations for presentations, serving as an immersive digital tool.

• Disadvantages: The scanner equipment itself is expensive, costing several million yen or more. In addition, operation requires detailed knowledge and data processing skills. Collected point cloud data can be enormous—often exceeding what a typical PC can easily handle—so processing may take time or require large, high-performance computers. Also, parts hidden from the laser beam cannot be measured, so the data obtained depends on the measurement angles and positions. Therefore, the scanner often needs to be repositioned at multiple points, which can require significant effort. For these reasons, small and medium-sized companies or low-budget projects often consider other methods.

• Use cases and examples: Effective where high precision and detail are required, such as current-condition surveys at construction sites, 3D scans of structures for BIM/CIM, recording ancient ruins, or converting large fixed objects into planar data.

• Accuracy: With good equipment and proper setup, very high accuracy on the order of a few millimeters can be achieved.

• Cost: Initial costs are particularly high, often several million yen per unit and in some cases exceeding ten million yen. Operational costs and data processing environments also require non-negligible expense.

Drone Surveying

Drone surveying uses unmanned aerial vehicles (drones) to capture the ground with photos or lasers and reconstruct the space in post-processing. Because drones can photograph wide terrain from the air at once, they are particularly strong for surveying extensive civil engineering sites: wide areas that would be difficult to cover manually can be 3D-modeled in a few hours. Drones can also photograph dangerous areas where people cannot enter (except for occluded parts). If equipped with laser sensors, they can obtain ground surface point cloud data even under dense foliage or complex terrain.

• Advantages: Able to collect wide-area data quickly and thoroughly analyze elevation differences and terrain. Drones can safely survey hazardous areas, making them useful in disaster investigations. Large sites that previously required extensive manpower can be surveyed by a small team with drones, reducing costs compared to traditional methods.

• Disadvantages: Flights and photography are subject to legal restrictions and permits. Urban or densely populated areas may face strict limitations. Weather and time of day must also be considered—measurements are difficult in rain, strong winds, or at night. Drone battery life is short, limiting continuous shooting time, so for large sites multiple flights are necessary. High-precision coordinates require drones equipped with RTK-GNSS or the establishment of ground control points, demanding specialized skills and equipment. Moreover, laser-equipped drones can cost tens of millions of yen when combining the airframe and sensors, making them much more expensive than basic photogrammetry.

• Use cases and examples: Effective for surveying entire civil engineering areas or construction sites, exploring rugged mountainous regions, or agricultural and forest ecological surveys where broad terrain and conditions need to be understood.

• Accuracy: Photogrammetry (including drone photos) generally achieves accuracy on the order of several centimeters depending on settings and calibration. Using RTK-GNSS on the camera or ground control points can yield horizontal accuracy around 2–3 cm, though vertical accuracy may be somewhat worse.

• Cost: If limited to photogrammetry, equipment costs can be kept relatively low, and entry costs can start from several hundred thousand yen. However, aiming for high-precision surveying requires RTK-equipped drones or laser sensors, which greatly increase costs.

Photogrammetry

Photogrammetry reconstructs spatial points from multiple photos by extracting matching elements across images. The fundamental principle is based on stereopsis from binocular parallax: integrating photos from multiple angles allows reproducing an object with proportional relationships. Recently, advanced algorithms called SfM (Structure from Motion) have developed, enabling automated reconstruction of sophisticated point cloud information on a PC. Historically used for aerial surveying, map creation, and drafting, modern advances in drone and camera resolution have made it easy to process on personal computers. [ Insert figure ]

• Advantages: A major attraction is that you can use widely available cameras or drones without special equipment. Costs can be kept low, allowing small- and medium-scale projects to start with modest budgets. Additionally, photos provide surface texture and color, so photogrammetry can capture realistic 3D data with surface appearance, useful for modeling ruins or producing 3D reconstructions for clients.

• Disadvantages: Processing multiple photos takes time; processing hundreds of images can take days on some PCs. Without understanding specialized software operations and processing methods, even large data sets may not be effectively utilized, requiring expertise. Surfaces without texture or with transparent glass cannot be reliably detected, so they cannot be measured directly. In such cases, it’s important to supplement photogrammetry with other methods. Consequently, photogrammetry accuracy is generally lower than laser or RTK-dependent methods.

• Use cases and examples: Suitable for cultural heritage reproduction, VR content creation, and creating design plans for houses and buildings where realistic digital reproduction is needed. Useful when drone or laser costs are too high, or when the fidelity of the subject’s appearance is important.

• Accuracy: Because it processes multiple observation points, initial measurement accuracy within effective planar ranges is often on the order of several centimeters, but it can produce reproductions with high compatibility with the real object.

• Cost: Depending on the number of photos and coordinate processing, photogrammetry is generally the cheapest in both time and money. However, the final data’s level of detail and accuracy lags behind some other methods, so it’s important to use multiple methods appropriately.

Simple High-Precision Surveying with the LRTK Method

The LRTK method realizes a new technology by attaching a compact RTK-GNSS receiver to a smartphone. RTK-GNSS refers to centimeter-level GPS technology (real-time kinematic positioning) that achieves high-precision global positioning. LRTK miniaturizes this further to a pocket-sized surveying device that can be carried one per person. [ Insert figure ]

By attaching an LRTK device to an iPhone or iPad, you can always measure high-precision coordinates on the spot. You simply align the device to the specified location and press a button to obtain positioning results such as latitude, longitude, and elevation. This allows people without extensive knowledge to acquire high-precision location information almost as simply as pressing a button. You can collect coordinates with LRTK for points you want to mark on photos, display those points on drawings in AR, or in some cases immediately display results using the smartphone’s LiDAR sensor or camera. For example, by using an iPhone’s LiDAR to perform a simple point cloud scan and overlaying LRTK position data on the acquired point cloud, you can easily obtain high-precision point clouds with absolute coordinates using only a typical power supply and a smart device.

• Advantages: The greatest benefit of this method is that high-precision surveying can be done easily without specialized surveyors. A single person can visit a site and collect high-precision coordinate data on the spot, and the data can be shared via the cloud from urban to mountain areas. RTK methods can obtain correction data from GPS satellites, enabling surveying even at night or in rain if corrections are available. With just a power supply, disaster sites can be surveyed simply with a smartphone. In this way, LRTK’s pocket-sized convenience for collecting high-precision position information suggests growing adoption. Once data is collected, it can be used immediately as practical results, allowing relatively easy verification and tracking on construction sites. If each person carries an LRTK device, site surveys that once took days could potentially be completed in hours. Additionally, compared to other methods, calibration and auxiliary measurement tasks are reduced, making overall costs lower. It may be said that the era when anyone can obtain high-precision 3D data themselves is approaching.

• Disadvantages: Currently, LRTK is not suitable for all situations. In urban environments, GNSS signals may be difficult to receive, and multipath errors from surrounding buildings can reduce accuracy. Also, because it relies on outdoor GNSS signals, it cannot measure indoors where signals are unavailable. Even considering these drawbacks, LRTK still offers a promising new option for sites and companies that require 3D surveying.

• Use cases and examples: Useful when you want simple, high-precision surveys at construction sites, when picking up several dimensional points of a single structure, or when partially replacing other methods in disaster sites or large projects to achieve high-precision site understanding without high costs.

• Accuracy: LRTK using RTK-GNSS can measure single points with errors on the order of about 1 cm. By averaging multiple measurements, horizontal accuracy below about 10 mm has been achieved.

• Cost: Because it is pocket-sized, initial costs are often on the order of several hundred thousand yen to assemble. Compared to drone RTK or airborne laser, it is relatively inexpensive to start, and even including app and cloud service fees, it is evaluated as a very affordable cost within construction IT adoption.

Summary: Choosing a 3D Surveying Method and Using LRTK

Below is a simple comparison table of each method’s accuracy and main advantages.

Reviewing the key points of each method: Laser scanner surveying can quickly collect highly detailed 3D structures but requires equipment and skills, which limits its use cases. Drone surveying can quickly acquire high-quality data over wide areas but is subject to flight restrictions and requires advanced piloting qualifications and skilled personnel. Photogrammetry may struggle on textureless surfaces and requires many photos and advanced processing, but it is attractive because it needs no specialized equipment and can be started affordably. For example, you can obtain wide-area terrain with drone photogrammetry and supplement key high-precision points with LRTK or ground surveying to balance efficiency and accuracy. Similarly, you could capture detailed complex structures with a laser scanner while covering the overall view with photogrammetry. By combining these methods appropriately, you can meet diverse survey needs. In particular, LRTK is a new technology being trialed even in fields that demand high precision. Because LRTK enables anyone to collect high-precision coordinate data with intuitive, tap-like operations similar to using a car navigation screen, it has the potential to bring new innovations to 3D surveying. For example, the fact that high-precision surveying—previously requiring large equipment on site—can now be carried out with existing personnel without significant effort greatly expands operational possibilities. If you are interested in new surveying tools and IT technologies, try the LRTK method once and experience its results firsthand.