How to Document Cultural Heritage with Terrestrial Laser Scanners | 6 Basics You Should Know Before Introduction

When considering methods for documenting cultural heritage, a major challenge is how to preserve shapes, dimensions, and spatial relationships that photographs alone cannot fully capture. Especially for subjects whose three-dimensional information itself holds value—such as buildings, stone structures, archaeological remains, sculptures, and gardens—planar records alone often cannot adequately support future research or conservation work. This is why three-dimensional documentation using terrestrial laser scanners has attracted attention.

A terrestrial laser scanner records an object's shape at high density by emitting lasers toward the object and surrounding space and acquiring numerous three-dimensional coordinates from the reflected signals. In the field of cultural heritage, it is becoming widespread as a method that is easy to apply for various purposes: capturing the current condition, comparing changes over time, recording before and after repairs, preserving for the future, and preparing data for public dissemination. However, simply introducing the technology does not automatically produce good records. If you proceed without understanding the nature of the subject, site conditions, required accuracy, and operational framework, the resulting data may be less useful than expected or require rework in later stages.

In cultural heritage practice in particular, it is not enough just to measure shape; what matters is which extent, at what accuracy, and in what form the information will be handed on to the future. On-site conditions often differ from general surveying or facility measurement: there may be restricted access, lighting constraints, surrounding environmental factors, visitor management, and preservation considerations. Therefore, it is essential to think about the technology in relation to the purpose of cultural heritage documentation, not just to evaluate equipment performance.

This article organizes six basics you should grasp before introducing terrestrial laser scanners for documenting cultural heritage. To make it clear for staff considering this for the first time, it explains, one by one, the method’s characteristics, suitable subjects, how to plan, the flow of on-site work, how to organize the acquired data, and perspectives for ongoing operation. The aim is to clarify criteria for the introduction decision and to help you acquire practical perspectives to produce three-dimensional data that can be used as cultural heritage records.

Table of Contents

• Understand the characteristics of information that terrestrial laser scanners can record

• Identify subjects suitable for cultural heritage documentation and those requiring caution

• Clarify the documentation purpose and required accuracy before introduction

• Learn the preparatory steps and workflow to ensure successful on-site measurement

• Design the post-acquisition data processing and how to compile documentation results

• Prepare position information and management methods with ongoing operation in mind

Understand the characteristics of information that terrestrial laser scanners can record

The primary feature of terrestrial laser scanners is their ability to record an object’s surface geometry as a large set of three-dimensional points. Conventional drawings and photographs organize information from limited viewpoints—plan, elevation, or section—but terrestrial laser scanners treat the entire space as a three-dimensional entity, making it easy to check arbitrary sections later or examine spatial relationships between distant parts as needed. For cultural heritage, where shapes are often complex and may need to be re-examined in the future, this ability to reinterpret the data later is highly valuable.

For example, it can be difficult to grasp all at once on site the tilt of a building’s columns, the settling of stone steps, surface wear on stone Buddhas, bulging of stone walls, elevation differences in a garden, or the layout relationships of archaeological remains. Photographs excel at conveying appearance intuitively, but they have limits in capturing accurate dimensions and depth. In contrast, three-dimensional point clouds numerically preserve shape itself, so even areas not initially prioritized can be reanalyzed easily when needed. Because cultural heritage documentation is often intended for long-term preservation, this reusability is extremely important.

Terrestrial laser scanners also have the advantage of acquiring large areas relatively quickly. They can record not only the object but its surrounding environment—building exteriors, precinct spaces, stone wall surroundings, clusters of remains—so they are effective when you want to preserve a cultural asset together with the space it occupies. The value of cultural heritage often depends not only on the object itself but also on context such as terrain, surrounding structures, circulation routes, and sightlines, so being able to capture broad spatial information integrally is highly meaningful.

On the other hand, terrestrial laser scanners are not omnipotent. What they acquire is basically surface information where the laser reaches and reflects; shaded areas, rear sides, and unseen interior spaces need to be supplemented from other positions. If you place great emphasis on fine carvings or very small surface irregularities, the distance to the subject and measuring conditions must be carefully considered, otherwise you may not achieve the expected point density. In other words, before introduction, you need to organize an understanding not that everything can be captured at high accuracy, but of what types of information the method excels at and under what conditions it shows weaknesses.

Additionally, appearance—color and texture—can be important in cultural heritage records. Because terrestrial laser scanners primarily aim to acquire shape, color reproduction and surface expression may need separate consideration. By centering on three-dimensional shape while also combining photographic records, existing drawings, field notes, and positional information, the completeness of cultural heritage documentation improves. In other words, a terrestrial laser scanner should be understood not as a standalone tool but as a method for building the foundations of cultural heritage records.

Grasping these basics allows you to set appropriate expectations at the evaluation stage. Rather than making three-dimensional capture the goal itself, consider how deeply you want to document the current condition and in what situations you will use the data in the future—this will make the value of terrestrial laser scanners clearer. In cultural heritage documentation, using the preserved information for the next steps is more important than merely measuring. From that perspective, correctly understanding the nature of the information that can be recorded is the first step before introduction.

Identify subjects suitable for cultural heritage documentation and those requiring caution

Terrestrial laser scanners can be applied across cultural heritage, but there are subjects where they are particularly effective and others that require operational adjustments. Understanding these differences before introduction makes it easier to create a realistic plan.

Firstly, the method is well suited to subjects with spatial extent, such as buildings and archaeological remains. Shrine and temple architecture, gates, storehouses, stone walls, stone steps, burial mounds, gardens, and groups of remains are all cases where the arrangement and overall shape matter more than individual components. For such subjects, thoroughly recording the whole current condition is highly meaningful. The data often becomes a versatile foundation for future repair planning, change detection, post-disaster comparison, and the preparation of materials for public use.

It is also suitable for surfaces that are not orthogonal or that have complex slopes. Cultural heritage does not always have the ordered forms of modern architecture; small distortions and irregularities from aging or historical construction techniques often remain. Because those irregularities themselves can indicate value or condition, the ability to comprehensively preserve information that simple dimensional measurement might miss—as three-dimensional point clouds—is a major advantage.

By contrast, caution is needed for subjects with very fine ornamentation, deep carvings, narrow spaces, or surfaces prone to reflection. For example, highly detailed carved surfaces or intricate decorative areas may not be fully captured depending on measurement positions or distances. While terrestrial laser scanners are suitable for recording the whole of large subjects, they do not uniformly guarantee ultra-high detail for surface texture and micro-geometry. Where necessary, planning to supplement with close-range photography or alternative methods will increase the practical value of the outputs.

Areas covered by trees or vegetation also pose challenges because only visible parts can be acquired. If you need a clear boundary between the ground surface and structures, special measures are required. Cultural heritage sites often have plantings, protective fences, and exhibition fixtures that appear in the point cloud. Some of this can be cleaned in post-processing, but if you don’t anticipate the level of noise up front, the results may differ from expectations.

Interior spaces can be effectively recorded as well, but narrow passages, many steps, or strict access restrictions make securing workable routes important. Cultural heritage facilities often require different considerations than ordinary buildings—permitted equipment locations, parts that must not be touched, visitor circulation, and lighting constraints. Therefore, determining whether a subject is suitable should take into account not only geometric compatibility but also whether the site can be safely and practically worked around.

In cultural heritage documentation, it is also essential to assess where the subject’s value lies. Do you need to preserve overall building distortion and spatial composition, compare surface deterioration of components, or understand relationships with surrounding terrain? The appropriate recording method depends on this. Terrestrial laser scanners are particularly strong at comprehensively capturing extensive subjects and complex spaces. Conversely, for projects where capturing extremely small details is the top priority, it is more practical to position the terrestrial laser scanner as a foundation for whole-site understanding and use other methods as the primary means for fine detail.

Misjudging this assessment can lead to disappointingly unusable data after acquisition. Before introduction, organize the subject’s size, complexity, access conditions, and the granularity of information you want to record, and decide whether a terrestrial laser scanner is the most suitable central method or should be combined with other recording techniques. For cultural heritage, the proper stance is not to force technology on the subject but to determine the role of the technology according to the nature of the cultural asset.

Clarify the documentation purpose and required accuracy before introduction

The most important consideration when evaluating the introduction of terrestrial laser scanners is to define the documentation purpose before thinking about equipment or work methods. Even for the same cultural asset, different purposes require different accuracy, point density, coverage, and types of deliverables. If this remains vague, you may acquire excessive data and increase processing burdens, or conversely lack necessary information and need to remeasure.

Documentation purposes broadly fall into categories such as preserving the current condition, pre-repair surveys, comparison of changes over time, academic research, public use, and management ledger maintenance. If the aim is to preserve the current condition, thorough coverage of the entire subject is emphasized. For pre-repair surveys, you need a granularity that allows interpretation of areas of deterioration and repair extents. For comparing changes over time, establishing standards that allow remeasurement under the same conditions later is essential. For public use, you should consider processing the data into forms that communicate well not only to specialists but also to general users.

Because the purpose changes the required accuracy, balancing required accuracy and operational load is crucial. It is common in cultural heritage work to assume that higher accuracy is always better, but in practice you must balance needs and workload. High-density acquisition increases data volume, processing time, storage needs, and difficulty in sharing. Conversely, if the data is too coarse, necessary checks cannot be made. What matters is deciding in advance what you want to interpret, the level of comparison you need, and what deliverables you will produce, then choosing acquisition conditions that are neither excessive nor insufficient.

Considering the coverage is important as well. It is not always sufficient to record only the cultural asset itself. Boundaries of the site, surrounding structures, approach paths, stone steps, terrain changes, and drainage directions often contain information relevant to the asset’s preservation and understanding. If you anticipate future uses, preserving not just the object but its context is often useful. However, expanding coverage without limits increases operational burden, so you should predefine how far to treat as a recording asset.

You should also decide in advance the expected deliverables. Beyond archiving the point cloud data itself, consider floor plans, elevations, sections, deterioration maps, explanatory materials, and foundational data for research. Planning how you will use the data reduces ambiguity in measurement conditions and post-processing policies. Cultural heritage documentation involves many stakeholders—field staff, preservation staff, researchers, designers, and administrative personnel—each with different viewing needs. Organizing who will use the data and for what purposes is a shortcut to maximizing the benefits of introduction.

Another major decision is whether repeated measurement is expected. One-off recording and longitudinal fixed-point monitoring require different approaches to references. If you plan to track changes over years, you must consider how to make it easy to reproduce the same location later, including strategies for alignment, handling of reference points, and coordinate management. This is extremely important in cultural heritage preservation; whether data can be left as comparable over time is heavily influenced by the design of the initial measurement.

By organizing these points before introduction, the meaning of adopting terrestrial laser scanners becomes clear. It clarifies not just the intent to create three-dimensional data but how deeply you will record the current condition and which departments and future generations will be able to use it. In cultural heritage documentation, continuity and reusability are as important as precision. Defining the purpose and required accuracy first is a fundamental determinant of whether a technology introduction succeeds.

Learn the preparatory steps and workflow to ensure successful on-site measurement

The quality of on-site measurement greatly influences overall quality in three-dimensional documentation of cultural heritage. Although some issues can be remedied in post-processing, omissions and lack of references tend to remain fundamental weaknesses, so preparatory work before entering the site is extremely important. Cultural heritage sites often have high barriers to revisit, limited access days, and scheduling constraints related to events or public openings, so it is essential to determine how much you can reliably capture in a single visit.

First, you need to understand the subject and create a measurement plan. Confirm the subject’s shape, site conditions, surrounding obstacles, visitor flow lines, access restrictions, availability of power, and condition of scaffolding, and plan where and in what order to measure. Because cultural heritage sites often prohibit contact or limit equipment transport, more careful circulation planning is required than for typical survey sites. Listing candidate measurement positions in advance reduces on-the-day confusion and prevents omissions and redundancies.

Next, assess blind spots. Terrestrial laser scanners only capture surfaces that are visible, so you must supplement from other positions for behind columns, under eaves, under stairs, deep recesses, and the far ends of narrow passages. Cultural heritage structures can be complex, and more parts may be hidden than you expect. Rather than wandering on site, anticipate where data gaps are likely and include positions in your plan to cover them.

On the day of work, it is effective to adopt a two-stage approach: whole-site acquisition followed by focused supplementary acquisition. First, acquire the exterior and main spaces in a way that ensures positional relationships across the site are connected. Then supplement important areas—sculpture details, deterioration zones, narrow spaces, and hard-to-see back sides. With this order, even if time becomes limited, you are likely to secure the overall framework. Unforeseen constraints often occur on cultural heritage sites, so advancing with priorities in mind is practical.

Also pay attention to variations in the surrounding environment. Human traffic, wind-induced plant movement, temporary structures, vehicles, and sunlight conditions affect point cloud noise and consistency. Many cultural heritage sites are open to the public, so you may need to work while avoiding visitors. Balancing safety and recording quality requires preparing choices of working hours and site partitioning to ease the burden on the day.

A commonly overlooked element on site is the importance of field notes. Recording what was acquired from which position and why, which areas required attention, and what compensations were made on-site greatly facilitates post-processing and report preparation. Leaving only point cloud data without contextual measurement conditions or decision background makes reuse difficult. It is important to keep records on site with future reinterpretation in mind.

Additionally, cultural heritage sites require an attitude of minimizing impact on the subject. Considerations such as equipment contact, placement locations, transport routes, number of workers, and protective measures should be handled carefully from a conservation viewpoint. Prioritizing efficiency in a way that increases physical contact risk or causes misunderstandings with site managers can be problematic. Three-dimensional documentation of cultural heritage is both a technical task and an action at the preservation site; therefore, balancing recording quality and conservation care is essential.

Successful on-site measurement requires not only proficiency with equipment but also subject understanding, path planning, priority setting, conservation consideration, and integrated on-site recordkeeping. For cultural heritage documentation, what matters is how much meaningful information you can take back in a single measurement opportunity. Therefore, in the preparation stage, concretely envision the site and build a workflow that distinguishes between information that is easy and difficult to capture—this is the most direct route to good deliverables.

Design the post-acquisition data processing and how to compile documentation results

Documentation of cultural heritage with terrestrial laser scanners does not end with on-site measurement. In fact, it is only when post-acquisition processing and the organization of results are included that the recordings function as documentation. For practitioners, having point cloud data is less important than keeping it readable in the forms needed when necessary. Therefore, when introducing the technology, you must design the post-processing workflow as well.

A basic task is merging point clouds acquired from multiple positions. For wide cultural heritage sites or complex buildings, it is usually difficult to capture everything from a single measurement, so you must align and merge data from multiple positions. If this merging is unstable, offsets may appear in wall surfaces or component relationships, and cross-sections cut afterward may look inconsistent. Since subtle tilts and irregularities can be important in cultural heritage documentation, managing the accuracy of merging is essential.

Next is cleaning up unnecessary data. Visitors, moving vegetation, temporary structures, nearby vehicles, and transient obstacles during measurement can make the point cloud harder to read. However, what is considered unnecessary depends on the purpose. For example, if you intend to record the surrounding environment, vegetation and terrain may be valuable. Conversely, if the goal is to check building deterioration, surrounding noise should be removed as much as possible. Thus, post-processing should be seen not as a task to make the visuals tidy but as work to organize information according to documentation objectives.

Designing deliverables is also important. Raw point clouds can be difficult to handle in day-to-day work. Converting the data into floor plans, elevations, sections, deterioration location diagrams, base maps for management, and explanatory images increases usability depending on the user. In cultural heritage, stakeholders vary widely, so separating detailed materials for specialists from easy-to-understand materials for managers and stakeholders enhances practicality.

File management practices cannot be overlooked. Cultural heritage documentation is not a short-term project; the data may be revisited years or decades later. Therefore, organize file names, acquisition dates, coverage, measurement conditions, processing history, coordinate information, and responsible personnel so that anyone can follow the contents. If data exists but it is unclear under what coverage or conditions it was acquired, it becomes difficult to use for comparisons. In cultural heritage documentation, the inheritable nature of the record is part of its quality.

If you plan for future updates, incorporate standards that make comparison easy at the initial stage of results organization. To facilitate overlaying the same area in later remeasurements, align on reference positions, storage units, display rules, and methods for extracting drawings. Records that can be read over time tend to hold more value than one-off documentation, making this perspective highly important.

During post-processing, you must also decide how far to refine the data. Overemphasis on readability can obscure the original roughness or distortion of the current condition. Conversely, leaving the data too close to raw form can make it impractical for operations. For cultural heritage documentation, you need to balance fidelity to the current condition with usability. A useful approach is to preserve raw data while creating derivative products tailored to specific uses.

Thus, the value of introducing terrestrial laser scanners is often determined more by the design of subsequent organization than by on-site measurement alone. To make the recordings meaningful as cultural heritage documentation, you must plan from the start how to clean the acquired point clouds, what deliverables to produce, and how to store them. Records do not come to life at the instant of acquisition but when the right people can use them at the right times. Designing post-processing with that perspective is the key to maximizing the benefits of introduction.

Prepare position information and management methods with ongoing operation in mind

If you truly want to make three-dimensional documentation of cultural heritage an asset, a single successful measurement is not enough. Prepare position information and management methods with future remeasurement, overlaying with surrounding information, multi-year comparisons, and integration with management materials in mind. Only then does terrestrial laser scanner documentation function as a sustainable foundation rather than a one-off deliverable.

Cultural heritage changes gradually over time. Weathering, settlement, tilting, repairs, changes in the surrounding environment, and disaster impacts manifest differently for each subject. To monitor these changes continuously, each point cloud must be managed in a comparable state. That requires clearly defining the positional reference used for recording, not merely creating a three-dimensional model. If positional references are ambiguous, year-to-year comparison becomes difficult and the recorded asset loses potential value.

Cultural assets do not exist in isolation but are managed in relation to their site and surrounding features. Giving positional context to data acquired with terrestrial laser scanners makes it easier to link with other ledger information, field survey results, photographic records, and repair histories. For example, it becomes easier to identify where a particular deterioration was observed or which area a given record is associated with, thus connecting the data to practical cultural heritage management.

At this point, it is important to establish management methods that anyone can operate. If only staff capable of advanced processing can use the data, utility tends to stop when personnel change or time passes. Define storage rules, folder structures, naming conventions, drawing standards, how to include position information, and the correspondence with record ledgers, and put them in a form that supports continuous use. In many cases, the system for handing over records is more important in the long run than the recording technique itself.

In practical operations, connecting detailed recordings from terrestrial laser scanners with routine position checks and supplementary surveys is also vital. While detailed three-dimensional records are highly effective, repeatedly measuring at the same scale can be burdensome. Therefore, having mechanisms to streamline broad positional understanding, spot checks, and sharing of recording locations increases the operational value of three-dimensional documentation. Bridging precise records and daily operations is often a practical challenge in cultural heritage management.

One practical option is to use peripheral devices that make positional information easier to handle. For example, combining terrestrial laser scanners with LRTK-type iPhone-mounted GNSS high-precision positioning devices can facilitate on-site position checks and sharing of recording locations. While terrestrial laser scanners provide detailed three-dimensional shapes, LRTK supports on-site positional awareness and operational efficiency. In cultural heritage recording and management, it is important not to treat the production of precise three-dimensional data as the final step but to link it to subsequent inspections, revisits, supplementary recordings, and stakeholder sharing.

Especially for sites managing multiple cultural heritage assets over time, being able to share recording locations without positional shifts, to handle positions confirmed on site among stakeholders, and to facilitate later comparisons and supplementary records becomes an operational advantage. By organizing positional information and building surrounding operations rather than relying solely on terrestrial laser scanners, you can better balance accuracy and continuity in cultural heritage documentation.

When considering the introduction of terrestrial laser scanners, it is important not only to evaluate whether measurements are feasible but also to consider how you will manage the acquired data and connect it to future surveys and conservation activities. The true value of cultural heritage documentation is judged by whether it is still usable years later, not by the satisfaction at the moment of acquisition. Therefore, as much as the precision of three-dimensional records, the design of position information, management methods, and ongoing operation deserves emphasis. With these perspectives, introducing terrestrial laser scanners can transform them from mere measuring instruments into a practical documentation foundation for passing cultural heritage on to the future.