What can you do with point cloud data of stone monuments? 6 examples of preservation and utilization

Interest in point cloud data is growing among practitioners responsible for the preservation, repair, and maintenance of stone structures. The targets include a variety of stone structures such as castle stone walls, temple and shrine stone steps, stone monuments, stone Buddhas, stone bridges, revetments, retaining walls, and stone boundary markers. Although these stone structures may appear robust, they change gradually over long periods. There is a great deal of management-critical information—such as stone displacement, joint opening, surface bulging, settlement, loss or damage, tilting, and relationships with the surrounding ground—but photographs and plan drawings often cannot convey these fully.

One solution attracting attention is point cloud data, which can record stone structures in three dimensions. Point cloud data captures the surface of an object as a collection of many points, allowing the three-dimensional shape to be preserved at high density. It can be used not only to preserve appearance but also for many practical tasks such as checking dimensions, creating cross-sections, comparing deformations, tracking before-and-after repairs, and sharing information among stakeholders.

In this article, assuming a practitioner searching for the query "stone structure point clouds", we clearly organize what can be done with point cloud data of stone structures from the perspective of preservation and utilization. While touching on the concepts you should grasp before adoption, we explain six practical use cases divided into six categories.

Table of Contents

• Why Point Cloud Data Is Required for the Preservation and Utilization of Stone Structures

• Basics of What Can Be Done with Point Cloud Data of Stone Structures

• Use Case 1 Record of Current Conditions and Longitudinal Comparison

• Use Case 2: Assessment of Distress and Repair Planning

• Use Case 3 Drafting and Cross-Section Verification

• Use Case 4: Post-disaster records and recovery decision-making

• Use Case 5: Sharing with stakeholders and consensus building

• Use Case 6 Public Use and Succession

• Practical points to keep in mind during implementation

• Summary

Reasons Why Point Cloud Data Is Required for the Preservation and Utilization of Stone Structures

Stone structures present difficulties different from those of wooden or steel structures. Each stone’s shape is irregular, and many are not fully standardized from the time of construction; years of wind and rain, earthquakes, freeze-thaw cycles, ground movement, and the effects of vegetation cause changes that do not manifest uniformly. Even when there appears to be no major visible damage, localized bulging or slight tilting may have accumulated.

Traditional recording methods have centered on photography, sketches, measured drawings, plans, elevations, and sections. Of course, these remain important. However, for subjects like stone structures, which have many irregularities, complex relationships between components, and require a three-dimensional understanding, two-dimensional records tend to be insufficient. Photographs are suitable for preserving appearance, but they are limited in spatial comprehension—such as how far a given point projects or where and how large any offsets are. Plans and sections help capture dimensions, but if you want to check a different section later, a follow-up on-site survey may be necessary.

Point cloud data are valued because they can capture and preserve the shape of objects broadly, in fine detail, and in three dimensions for such challenges. Based on three-dimensional information acquired on site, you can later generate the necessary cross-sections, compare datasets from multiple time points, and evaluate repair areas, making them effective for both preservation and practical use.

In the conservation of stone structures, there tend to be many stakeholders. Owners, managers, designers, contractors, conservation staff, administrative officials, researchers, and others in different positions need to make decisions while looking at the same object. In such cases, records that allow the three-dimensional shape to be treated as a common reference—such as point cloud data—greatly enhance the quality of explanations. They also make it easier to convey the condition to stakeholders who have not seen the site, and can improve the accuracy and speed of deliberation.

Basics of What Can Be Done with Point Cloud Data of Stone Monuments

Put simply, what point cloud data of stone structures can do is record the current state in three dimensions and make that information available for subsequent processes. However, the important point here is that point cloud data is not merely a "good-looking 3D." A point cloud is a collection of many points with positional information, and it forms a foundation that can be used in practical tasks such as capturing shape, verifying dimensions, comparing, producing drawings, and sharing.

For example, for stone walls it can be used to capture surface irregularities and protrusions. For stone steps, it helps examine variations in riser heights and treads and assess hazardous spots for passage. For stone monuments and stone Buddhas, it is suitable for documenting surface wear and loss, the remaining traces of inscriptions, and the preservation of fine-scale shapes. For bank revetments and retaining walls, it makes it easier to understand their relationship with the surrounding terrain and changes along their length.

Another characteristic of point cloud data is the wide range of ways it can be used after acquisition. You can extract cross-sections at required locations, measure the distance between two distant points, capture the target area as a surface, compare the amount of change at specific locations, and use it to create two-dimensional drawings. In other words, by recording the site in three dimensions once, it becomes easier to accommodate multiple purposes later.

However, point cloud data are not automatically usable just because they have been captured. You need to decide in advance why you are recording it, what level of accuracy is required, what area will be covered, and what kinds of deliverables it will be turned into after acquisition. Whether the purpose is archival recording, use for repair design, or linking to a maintenance management ledger will change the required measurement density and scope of work. With this premise in mind, let’s look at specific use cases.

Use Case 1 Current Condition Recording and Comparison Over Time

The most fundamental and also important use is recording the current condition. Stone structures inevitably change over time. However, those changes often progress slowly, and when you look at them every day you may not notice. Therefore, by preserving the state at a certain point in time as point cloud data, you can have a baseline for future comparisons.

For example, on castle stone walls, slight bulges on the surface or changes in the positional relationships of the stones can affect long-term safety. Changes that were traditionally tracked with fixed-point photographs and observations of some cross sections can be recorded in three dimensions over the entire target area if point cloud data are available. If the same area is re-measured in the next survey, it becomes easier to identify which parts have changed across the surface.

The same applies to stone steps at temples and shrines. The progression of wear on individual steps, localized settlement, edge damage, and the interface with the surrounding ground can be difficult to grasp from photographs alone. If recorded as point cloud data, you can later check riser dimensions and tread unevenness, and year-to-year comparisons make it easier to discern deterioration trends.

Even for objects whose form itself has cultural value, such as stone monuments and stone Buddhas, records of their current condition are particularly important. When weathering, surface flaking, loss, or tilting have progressed, whether there exists a record that can objectively show what the condition was in the past greatly affects the quality of subsequent preservation decisions. Photographs are important, but with point cloud data you can preserve not just the appearance but the form itself for future generations.

In practice, it is important not to treat the survey at the time of investigation as a one-off, but to organize the recording system with future re-measurements in mind. If it is clear exactly what area was covered, which reference points or coordinate system were used, and how much of the surrounding topography was included, comparisons in subsequent surveys will be easier. The value of point cloud data lies not only in the results of a single measurement but in its role as the foundation for ongoing management.

Use Case 2: Condition Assessment and Repair Planning

In the management of stone structures, detecting signs of deterioration is especially important. Cracks, open joints, displacement of stone units, bulging of surfaces, localized settlement, and the like are conditions you want to identify early, but it is not easy to grasp the overall picture by visual inspection alone. This is particularly true for elevated or long structures and irregular masonry, where judging based on only partial observations can easily lead to oversights.

By utilizing point cloud data, it becomes easier to organize the positional relationships of problem areas while viewing the entire stone structure in three dimensions. For example, if a bulge is seen in part of a stone wall, you can more easily assess how far the impact extends by checking the surrounding slopes and the continuity of the masonry surfaces. It is also well suited to continuously assessing the condition of long, extended structures such as retaining walls or revetments.

Also, in repair planning it is necessary not only to identify damaged areas but to clarify the scope and degree of intervention. When considering whether partial repairs will suffice, whether broader remediation is required, and how to secure temporary works and construction access routes, three-dimensional information makes it easier to share the basis for decisions. Even if site personnel and design personnel are in different locations, they can discuss the same geometric information, which improves the quality of meetings.

Point cloud data is also effective for renovating stone steps. By grasping in three dimensions the variation in step heights, partial settlement, and edge damage, it becomes easier to develop repair plans that balance user safety and preservation. For subjects like stone bridges and stone arches, the ability to check not only the upper shape but also the surrounding terrain and the relationship with attachment points is useful.

Of course, repair strategies are not determined solely by point cloud data. Point cloud data must be combined with other investigations such as the extent of material deterioration, the presence or absence of internal cavities, water flow, and past repair history. Even so, having point cloud data as the basis for understanding shape is extremely effective in improving the accuracy of repair planning. In the conservation of stone structures, understanding the shape often serves as the starting point for decision‑making.

Use Case 3: Drawing Creation and Cross-Section Verification

One of the major advantages of point cloud data is that it makes it easy to produce the drawings needed later. In the recording and design review of stone structures, plan, elevation, and section drawings are often required. However, irregular stone structures with significant surface variations are time-consuming to measure using traditional surveying methods and are prone to requiring additional surveys for drafting.

If you have point cloud data, you can extract cross-sections at the necessary locations, making it easier to proceed with drafting based on those sections. For example, if you want to check changes in the slope of a stone retaining wall, assess subsidence at a specific cross-section of stone steps, or clarify the arch shape of a stone bridge, you are more likely to be able to confirm these from the acquired data without having to remeasure on site.

This is useful not only for preservation surveys but also for design and construction preparation. When creating repair planning drawings, if surface irregularities and deviations in the normal direction can be identified, it becomes easier to assess the required scope of intervention. If the surrounding topography is acquired at the same time, it also facilitates considerations of drainage, movement lines, and temporary works.

Even for subjects such as stone monuments or stone Buddhas, examining cross-sections is meaningful. This is because it enables three-dimensional confirmation of information that photographs alone cannot fully capture, such as the degree of surface wear, the depth of material loss, and the relationship with the pedestal. As preservation records, the ability to add cross-sections as needed, in addition to plans and elevations, is also a major strength.

What is important here is to decide the measurement scope from the outset with the final deliverable in mind. If you intend to produce drawings but only capture the surface, or intend to extract cross-sections but fail to include the surrounding area, you will encounter shortcomings in downstream processes. When utilizing point clouds of stone structures, organizing at the time of measurement "what kind of drawings or decisions it will be used for" determines how usable the results will be.

Use Case 4: Post-disaster Documentation and Recovery Decision-Making

Stone structures can suddenly suffer major damage from earthquakes, heavy rain, landslides, frost damage, fallen trees, vehicle collisions, and other causes. In such cases, it is important to record the post-disaster condition as quickly and accurately as possible. Even while prioritizing emergency response, if you do not document which parts changed and how, it can hinder recovery planning and later verification.

Point cloud data is well suited for recording complex post-disaster conditions over wide areas. Because it can capture in three dimensions the distribution of collapsed stone materials, the tilt of remaining elements, the occurrence of level differences, and changes in the surrounding terrain, it has value as reference material for later analysis. Even when a site is unstable and prolonged on-site stays are difficult, being able to record a wide area in a short time makes it easier to advance recovery planning off-site.

Furthermore, if pre-disaster point cloud data remains available, comparing it with post-disaster data makes it easier to identify where and by how much displacement occurred and what was lost. This is extremely important not only for considering restoration policies but also from the perspective of archival preservation. In particular, for stone structures of cultural value, restoration that closely matches the original state is often required, and the availability of materials that allow objective comparison of pre- and post-disaster shapes can make a significant difference.

Stone walls, stone steps, stone bridges, stone monuments, stone Buddhas, and so on — the damage patterns vary depending on the subject, but what they share is the importance of being able to grasp both the "pre-loss state" and the "state immediately after the disaster." Point cloud data functions as the record that links these two. Photographs are, of course, necessary, but having a record of the three-dimensional shape makes recovery discussions more concrete.

Because time is limited during disaster response, it is operationally useful to organize in advance which assets should be prioritized for recording. It can be too late if you only realize their importance after a disaster occurs. Point cloud data is a highly valuable means both as a preventive record in normal times and as an emergency record after a disaster.

Use Case 5 Stakeholder Sharing and Consensus Building

In the conservation and utilization of stone structures, achieving a shared understanding among stakeholders is extremely important, not just technical correctness. Owners and managers emphasize safety and maintenance costs; conservation specialists prioritize preserving the original form and historical value; designers and contractors consider constructability and construction processes. Researchers may place importance on documentation and scholarly interpretation. With these differing perspectives, how the condition of the subject is shared can determine the success or failure of the overall plan.

Point cloud data is effective as a basis for this kind of consensus building. This is because it allows features that are hard to convey in two-dimensional drawings—surface irregularities and slopes, the positional relationships between stones, and connections with the surrounding terrain—to be shared as three-dimensional information. It becomes easier to discuss while viewing the necessary locations without repeatedly visiting the site. Especially in projects with remote stakeholders or decision-makers, it makes it easier to advance deliberations while reducing the number of on-site inspections.

For example, even if part of a stone wall requires repair, opinions may differ depending on one's standpoint about how extensive the intervention should be. In such cases, sharing the overall geometry and the spatial relationships of problem areas based on point cloud data makes it easier to move beyond subjective debate. Likewise, for safety measures on stone steps, being able to present user movement patterns and variations in step heights three-dimensionally facilitates discussions about balancing preservation and safety.

Also, even in projects that involve resident briefings or public use, point cloud data serves as the foundation for explanatory materials. This is because it makes it easier to create materials that intuitively convey the shape of the subject, rather than drawings that only experts can understand. Of course, the information ultimately needs to be converted into clear, well‑organized expressions, but having solid spatial information as the basis is highly significant.

The preservation of stone structures cannot be accomplished by technology alone. It proceeds on the basis of understanding and agreement among diverse stakeholders. In that sense, point cloud data is not only a recording technology but also a foundation that supports communication.

Use Case 6 Public Use and Succession

Point cloud data of stone monuments is useful not only for preservation and repair but also for public use and for passing information on to future generations. The value of stone monuments lies not merely in preserving them as objects, but also in conveying their presence and condition to the next generation. However, there are cases where adequate utilization is difficult due to circumstances such as being hard to understand without visiting the site, limited access because of distance, entry restrictions, or the inability to approach in order to prevent deterioration.

Even in such cases, if point cloud data is available, the shape of the subject becomes easier to handle digitally. This is because, based on the raw data kept as a preservation record, it can be more readily developed for research, exhibitions, education, and the creation of explanatory materials. For example, for subjects whose shape itself carries information—such as reading inscriptions and surface morphology on stone monuments, comparing the wear conditions of stone Buddhas, or explaining the structural features of stone walls—the value of three-dimensional records is high.

Moreover, even if repairs, relocation, or site improvements are carried out in the future, if pre-existing point cloud data is retained, the pre-modification state can be referenced. This is not merely the preservation of memories; it has meaning as a management record. Being able to trace what condition something was in at any given time is also important from an asset management perspective.

It is also effective from the perspective of knowledge transfer. The subtle differences in shape and signs of danger that experienced workers read on site cannot be completely automated and replaced, but if they are at least preserved as three-dimensional information, they can serve as material for successors to study by examining them. Because the management of stone structures is long-term, it is important to retain comparable information so that comparisons remain possible even when those responsible change.

Even if the aim is public use, it is preferable to ensure accuracy and coverage suited for practical use at the initial acquisition stage. Lightweight data collected only for display may later be unusable for restoration planning or comparative analysis. Conversely, data recorded thoroughly as preservation records can be more easily adapted for public release as needed. Point cloud data of stone structures should be regarded not as separate for preservation and utilization, but as an asset that connects both.

Practical Points to Keep in Mind During Implementation

To successfully utilize point cloud data of stone structures, organizing the practical objectives must come before the names of equipment or methods. The first thing to clarify is what you are recording for. Whether the primary purpose is preservation records, use in repair or restoration design, integration with a maintenance management register, or creating a comparison baseline for disasters will change the required accuracy and scope.

Next, defining the scope of the subject is important. Recording only the stone structure itself is not always sufficient. If you do not include elements that will later serve as material for decision-making—such as the surrounding ground, drainage routes, connected structures, movement routes, and the extent of vegetation influence—you may find the data insufficient when putting it to use. This is especially true for subjects where the relationship with surrounding conditions is important, such as stone walls, revetments, and stone steps; isolating and recording only the main structure can make the records difficult to use.

Furthermore, coordinate management that anticipates future re-surveys is important. If you want to make comparisons over time, acquiring data against different reference standards each time will undermine the reliability of those comparisons. By managing positions consistently and keeping them in a state that can be overlaid onto drawings and other survey results as needed, you increase the value of the data.

The design of the deliverables is also indispensable. Rather than simply handing over the point cloud data itself, you need to consider in what form it will be returned to the site. Whether cross-sectional drawings are required, elevation drawings are required, a 3D view for stakeholder presentations is required, or secondary processing usable for repair planning is required will determine how the work is organized.

And what is easily overlooked is storage and management after acquisition. Even if you go to the trouble of measuring, its value diminishes if the files’ whereabouts become unknown, if nobody can open them, or if they cannot be referenced during the next survey. Point cloud data’s value comes not from simply saving it, but from managing it in a reusable state. It is important to organize file names, measurement dates, the surveyed area, reference information, and links to related drawings.

Summary

What can be done with point cloud data of stone structures is not limited to mere three-dimensional visualization. It is useful across a wide range of preservation and utilization contexts — from documentation of current conditions, comparisons over time, and assessment of deterioration, to repair planning, creation of drawings, decision-making for post-disaster restoration, sharing among stakeholders, and public use and transmission to future generations. Especially for objects like stone structures, whose shapes are complex and for which a three-dimensional grasp of condition is important, the value of point cloud data is very high.

However, what’s important is to clarify at the outset "what you are collecting it for." If the purpose remains ambiguous, the required scope and level of accuracy cannot be determined, and the data you’ve gathered will be difficult to leverage. You should organize whether you intend to use it as a preservation record, to inform repair design, or as a standard for ongoing management, and plan with future reuse in mind.

Furthermore, in the management of stone monuments, operations that link point cloud data with positional information are becoming increasingly important rather than relying on point cloud data alone. If it is clear which stone monument was recorded, when, where, and over what extent, re-measurement, comparison, and organizing relationships with the surrounding environment become much easier. When you want to easily perform on-site positioning, simple surveying, and coordinate management of records, using an iPhone-mounted GNSS high-precision positioning device, LRTK, is also effective. To turn point cloud acquisition and maintenance management of stone monuments into a system for preservation and practical use on site rather than a one-off record, LRTK helps connect practical workflows. If you want to make the preservation and utilization of stone monuments more reliable, it is important to establish an easy-to-use on-site simple surveying environment alongside point cloud data.