Four Considerations for Documenting and Preserving Cultural Heritage Graves with 3D Scanning

In the work of documenting and preserving graves that are cultural properties, simply keeping their appearance tidy is not enough. When looking ahead to later investigations, conservation and repair, comparative studies, and public use, what is required is not "to reproduce the shape visible on site" but "to leave records that can be re-examined in the future." In the cultural property field, three-dimensional measurement is effective for recording and preserving three-dimensional forms, and digital archives are positioned as the foundation for passing records on to the future. In recent years, concern has grown over the loss of historical materials due to the removal and dispersal of medieval and early modern graves, further heightening the importance of recording graves.

Table of Contents

• The significance of recording and preserving cultural heritage tombs through 3D scanning

• Note 1: Define the purpose of storage first

• Note 2: Give top priority to protecting cultural properties and obtaining permission

• Note 3: Design the measurement method according to the required accuracy

• Note 4: Consider the task complete only after long-term preservation of the data is included.

• Common mistakes that occur on-site

• Practical approaches to improving the quality of record keeping

• Summary

The significance of documenting and preserving cultural heritage tombs using 3D scanning

The value of graves as cultural properties is not determined solely by the shape of the stone itself. There are multiple overlapping layers of information to be interpreted: the progression of surface weathering, the extent to which inscriptions remain, the tilt of components, their relationship with the surrounding topography, the context of their arrangement, traces of repairs, points of damage, changes since erection, and so on. Two-dimensional photographs are important, but they are easily affected by angle, shading, and perspective, and sometimes cannot adequately convey three-dimensional information.

By using 3D scanning, it becomes easier to record a tomb’s three-dimensional shape and sense of scale more objectively, and to review it later from different viewpoints. In the field of cultural heritage, three-dimensional measurement is understood to allow the digital recording and preservation of form and size, facilitating a wide range of applications including conservation, research, exhibition, and education.

Graves in particular are highly susceptible to the effects of wind and rain, vegetation, ground movement, changes in management, and so on. Even if in-situ preservation continues, the same condition may not be maintained in the future. There are many situations where 3D data is useful: comparing before and after collapse or loss, verifying before and after repairs, recording prior to relocation, providing alternative access for non-public areas, and sharing with researchers in distant locations. For stone cultural properties such as gravestones and stone pagodas, the ability to record without contact is itself a major advantage, and the fact that documentation can proceed while avoiding contact-based methods is also important.

However, it should not be misunderstood that introducing 3D scanning will automatically produce "good preservation records." Even if you create an attractive 3D model, it is insufficient as a preservation record if standards are unclear and dimensional comparisons cannot be made, if poor imaging conditions render inscriptions unreadable, if the raw data are not retained and cannot be reanalyzed, or if rights issues are not resolved and the data cannot be shared. What is truly important when documenting tombs of cultural heritage with 3D scanning is to design the process to include the steps before and after measurement. From here, I will explain, in order, the four considerations you should keep in mind.

Note 1 Define the purpose of storage first

The first point to note is to define in advance what the record is for. If you start measuring while leaving this ambiguous, you will almost certainly have to redo work later. Even when someone asks to 3D-scan a cultural heritage grave, the actual purposes vary. Whether you want to create baseline documentation for conservation of the current condition, use it to assist reading inscriptions, compare before-and-after repairs, produce a public model for educational outreach, or record the layout relationships of the entire burial area will change the required accuracy, the extent to be captured, and the data that should be retained.

For example, if the goal is a model for public viewing, lightweight data and well-balanced color rendering that are easy for users to view are emphasized. On the other hand, if it is to be preserved as baseline material for conservation/restoration or academic research, fidelity of shape, dimensional reproducibility, and retention of the original images and processing history are more important than making it look light. If the main objective is observing grave inscriptions or surface finishing, the shooting density of the sides and top, shadowing conditions, and the representation of surface roughness will determine success or failure. If the target is the mound or the entire burial area, you must capture not only individual tombstones but also the surrounding terrain, approach paths, row arrangements, slopes, and their relationships with boundaries, otherwise the context will be lost later.

When the definition of the objective is vague, on-site decisions tend to default to "just photograph everything." However, that may seem safe at first glance but is actually dangerous. Even if you think you've photographed everything, necessary angles may be missing, the prioritization of the target areas may be unclear, and the resolution of important parts may be insufficient. Furthermore, only the amount of data increases, swelling the burden of storage and organization. For the documentation of cultural heritage, more quantity is not necessarily better; it is important to organize records in a form that will withstand later use.

Therefore, before starting work you should at a minimum decide which of the following will be the primary purpose: recording the current condition, recording the shape, observing inscriptions, comparative verification, or public use. If there are any secondary purposes, those should also be specified. Once this is decided, the target scope, required accuracy, imaging methods, delivery format, and preservation rules can all be determined consistently. Conversely, if this is left vague, no matter how carefully work is carried out on site, the resulting outputs tend to be difficult to use.

Note 2: Prioritize cultural property protection and obtaining permissions.

The second point to note is to prioritize the protection of cultural properties and to organize permissions and operational rules in advance. A gravesite that is a cultural property should be treated as an object of protection before it is treated as a research subject. You must avoid touching the object for the sake of easier measurement, moving the surrounding environment carelessly, or forcibly placing temporary structures. In 3D measurement of stone objects, the ability to document them non‑contact is a major advantage, and avoiding methods that involve physical contact has been shown to provide preservation benefits.

In the field, more important than simply not touching is arranging work so that touching becomes unnecessary. The permissible tasks vary depending on whether a grave is inside a protective shelter, within a protective fence, on a slope, surrounded by dense trees, or located along routes used for memorial services and worship. Consideration of religious sensitivities and local sentiments is also essential. Whether or not a site is designated as a cultural property, graves often carry local memory and ritual contexts, so taking photographs just because it is technically possible undermines trust. It is essential to clarify in advance, among cultural heritage officials, owners, managers, and local stakeholders, the areas where photography is allowed, working hours, the extent of what will be made public, and the conditions for reuse.

One thing that is easily overlooked here is permission for publishing data. Even if you obtain permission to take measurements on site, that does not necessarily mean you have permission to publish or allow secondary use. Digital archive guidelines also emphasize clearly stating conditions for secondary use, providing sustainable management, and offering data with interoperability in mind. In other words, for 3D data, how you handle it is as important as creating it. JapanSearch

There are cases where it is better not to widely disclose the locations of graves that are cultural properties. This is because of the risks of theft, damage, and unauthorized entry. Whether you publicly release high-resolution models as-is, publish only a simplified version with location information withheld, limit access to academic use, or restrict use to within the agency or museum will change the composition of the deliverables you need to produce. If you proceed while permissions and publication conditions remain unclear, you may end up with data that cannot be used after completion. In 3D scanning of graves that are cultural properties, it is important to understand that preservation and public access are separate issues.

Note 3: Design measurement methods according to the required accuracy

The third point to note is to design the measurement method according to the required accuracy. When 3D scanning graves of cultural properties, the most common mistake is to confuse a "model that looks highly detailed" with "data that can be used as a conservation record." Even if it appears smooth on screen, if the dimensional reproducibility is insufficient, the coordinate reference is ambiguous, or shadowed parts are missing, it becomes difficult to use for comparative verification.

In grave documentation and preservation, it is necessary to consider the scale of the subject. The appropriate method differs depending on whether you want to record a single gravestone or stone monument in detail, preserve the interior of a burial chamber, or capture the topography of a tumulus or the entire burial area. If you prioritize surface inscriptions and fine carvings, close-range measurement is required, and if you need to capture grave groups and their topographical context, individual high-detail models alone are not sufficient. Rather, the concept of combining the overall layout with individual details is important.

Measurement accuracy is also affected by the condition of the subject. Heavily weathered stone, wet surfaces, strong direct sunlight, deep shadows, moss or soil deposits, confined spaces, scaffold constraints, and insufficient vertical visibility can all cause a decline in quality. Graves of cultural properties are often outdoors, and environmental conditions frequently have more impact on quality than the measurement equipment. Trying to force a quick finish on-site increases the likelihood of missing parts, distortions, and texture breakdowns. Therefore, during a preliminary survey you should check for blind spots, access restrictions, sunlight conditions, vegetation, and post-rain conditions, and, if necessary, consider the time of day and even the season for photography.

The important point here is that increasing accuracy alone is not the right solution. If unnecessarily detailed data are requested, processing time, storage capacity, and operational burden will surge, and as a result sustainability will decline. In the field of three-dimensional cultural heritage data, risks have been pointed out that diversification of formats, inconsistent metadata, and inadequate preservation methods could render data unusable in the future, and an overall design covering acquisition through management is required. Archaeological Materials Report Database

Therefore, in accuracy planning it is more practical to judge not by "how many millimeters need to be resolved" but by "whether comparisons, observations, and reuse that fulfill the project's objectives are possible." Whether the work is meant to assist inscription reading, enable year-to-year comparisons, check component displacement, or update site plans will change how you place control points, assign coordinates, and separate overall from partial elements. In the recording and preservation of cultural-property graves, it is particularly important not to confine work to a standalone model but to consider how to retain the positional relationship with the entire burial area.

Note 4 Consider the task complete only when long-term data preservation is included

The fourth point to note is not to consider the work finished when you create a 3D model, but to regard it as complete only when long-term preservation is included. In fact, this is the aspect most easily overlooked and the one that later makes the biggest difference. In the cultural heritage field, 3D digital measurement data are processed into multiple formats such as point clouds, meshes, and images, and because technological progress is rapid, it has been pointed out that whichever format is chosen will require planning for the future lifespan of systems. In addition, it is desirable to preserve for the long term not only the final deliverables but also the acquired data converted into geodetic coordinates, the ancillary information obtained through observation, and, in some cases, the original data. Nara National Research Institute for Cultural Properties repository

This idea is particularly important for the recording and preservation of cultural heritage graves. This is because interpretations of graves may change in the future. Inscriptions that are unreadable at present might become legible through future visualization technologies or comparative research. Original images that seem unnecessary now may play an important role when reprocessed years later. Reports on 3D measurement of stone monuments also state that source images do not become unnecessary after creating 3D models and are important for verification by third parties and future generations, and for information recovery by future technologies.

Archaeological Materials Report Database

From the perspective of long-term preservation, it is essential to organize and retain not only the finished model but also the original images, the main data before and after processing, coordinate information, capture date and time, photographer, subject name, location management information, scope of permissions, usage conditions, processing methods, the standards used, version history, and so on. In digital archives, emphasis is placed on managing not only the content but also the metadata and previews to enable long-term preservation and access. Ensuring interoperability is also important, because storage methods that only specific personnel can read may become unusable after a few years.

Furthermore, it is important to separate data according to each recipient. Designing a complete version for internal archival storage, a high‑precision version for research use, a lightweight version for public release, and a still‑image version for explanatory purposes will make the data easier to use. Conversely, leaving only one massive dataset can mean that no one can handle it and it ends up buried. In the record preservation of cultural heritage tombs, quality is not just high measurement accuracy, but leaving the data in a form that people in the future can actually use.

Common Mistakes Likely to Occur at Worksites

So far we've looked at four points of caution, but several mistakes are repeatedly made in the field. The most common is photographing only the object and feeling reassured, without leaving enough of the surrounding context. A grave does not exist on its own; it gains meaning within the burial area, the approach path, slopes, rows of stones, nearby facilities, orientation, and the sense of distance to its surroundings. Even if a standalone 3D model is beautifully made, if information about where and how it was placed is not preserved, its value as a preservation record is greatly diminished.

Another common issue is relying solely on colorized models when you want to read inscriptions or assess surface condition. Color reproduction is important, but subtle surface undulations and signs of wear can sometimes be easier to discern from the way light falls and from shadowing. The representation suited for shape observation and the representation suited for understanding appearance are not the same. If you do not distinguish between outputs intended for research and conservation and those intended for public display, you will end up with results that are half‑baked for both.

It is also common for follow-up organization to fall behind, causing file names to become inconsistent and shooting locations or processing details to become unclear. This is less a technical failure than a failure of record management. For subjects expected to undergo ongoing surveys and year-to-year comparisons—such as graves that are cultural properties—a naming convention and storage structure that future staff can immediately understand are indispensable. It is necessary to design the workflow so that the data can be organized after returning, as much as you take care when photographing in the field.

Furthermore, in the rush to publish, the handling of location information and high-resolution data may be treated lightly. While it is important for cultural heritage to be widely known, it is not appropriate to release everything as-is. Openness and protection should be considered together, and it is desirable to design staged measures for factors such as location disclosure, viewing permissions, resolution, and whether downloads are permitted. If this judgment is postponed, you may end up with data that cannot be used after completion or that should not have been released.

Practical Approaches to Improving the Quality of Recordkeeping

When documenting and preserving cultural heritage graves with 3D scanning, it is effective to think in three stages—before, during, and after fieldwork—to stabilize quality. In the pre-fieldwork stage, define the purpose, target scope, permissions, required accuracy, deliverables, and preservation rules. During fieldwork, reduce blind spots, capture both the overall and the detailed elements, and avoid discarding the surrounding context. In the post-fieldwork stage, carry out all tasks at once: archive the raw data, organize the primary deliverables, attach metadata, create backups, and set the sharing scope. The important point is to have the mindset that record preservation is not complete when the 3D model is finished, but only when it has been stored and documented in a reusable form.

Furthermore, for graves designated as cultural properties it is effective to record both the object itself and its spatial relationships. In addition to precisely preserving the details of gravestones and stone pagodas, if you also organize the overall layout of the burial area, the reference positions, the photo locations, and the relationships with surrounding structures, later comparisons and revisit surveys become overwhelmingly easier. On site, the clearer it is from which point something was photographed, what was photographed, what direction you were facing, and which reference you used to link the whole, the more reliable the record becomes.

If there is a system that allows on-site coordinate checks and quick sharing of survey points, the overall accuracy and reproducibility of the work improves. In surveys of cultural-heritage graves, attention tends to focus on the 3D data of the grave itself, but in practice it is just as important to stably preserve the positional relationships with the surrounding area. This is especially true for multi-day surveys, follow-up records spanning seasons, organization of entire cemetery areas, and comparisons before and after repairs—if the handling of on-site coordinates is ambiguous, you will run into difficulties later. In such situations, combining means that can nimbly confirm and share location on site, such as LRTK, an iPhone-mounted GNSS high-precision positioning device, makes it easier to link the 3D records of the cultural-heritage grave itself with the management of on-site coordinates. When building records not as standalone models but as information about the whole site, these auxiliary tools are extremely well suited.

Summary

The considerations when documenting and preserving cultural heritage graves with 3D scanning are not simply about equipment selection or shooting techniques. Define the preservation objectives first; give top priority to cultural heritage protection and obtaining permissions; design measurement methods according to the required accuracy; and consider the work complete only when long-term data preservation is included. By covering these four points, you move beyond 3D models that merely look good toward records that can withstand future investigation, repair, comparison, and transmission to future generations.

Graves of cultural properties cannot be recorded after they are lost. That is precisely why what should be preserved now is not only the form on site but information that future generations can re-examine. 3D scans that preserve the details of gravestones and stone pagodas, and operational practices that stably organize the positional relationships and reference information of the entire graveyard, should inherently be considered together. If you want to advance the recording and preservation of cultural properties in a more practical and more reusable way, it is important to review not only the acquisition of 3D data but also the verification and sharing of site coordinates. As a means to support that field operation, using LRTK can transform the recording and preservation of cultural-property graves from one-off measurements into an ongoing, cumulative record infrastructure.