3D点群スキャンで変わるエクステリア設計：LRTKで完成イメージを見える化

The term exterior refers to the entire outdoor area of a detached house, such as the garden, parking area, gates and walls, approaches, tiled paving, and privacy fences. Exterior design requires accurately understanding and planning not only aesthetics and functionality but also slight site shifts and elevation differences. For example, differences in slope or dimensional errors on the order of a few centimeters can lead to problems like poor rainwater drainage or malfunctioning fence gates. However, traditional manual measurements and reading drawings alone could miss subtle on-site differences or fail to fully convey the finished image to the client.

One emerging technology that addresses these challenges is 3D point cloud scanning. Recently, a convenient high-precision surveying system using smartphones called LRTK makes it possible to obtain centimeter-level 3D data simply by walking the site, which can be used in design and construction. This article explains the changes and benefits that 3D point cloud scanning with LRTK brings to exterior work. From accurately capturing current site conditions to sharing finished images via CAD and AR, improving site management and construction accuracy, and the ease of smartphone surveying, let’s examine how the latest technology is revolutionizing exterior design.

エクステリア設計で求められる「センチメートルの精度」

In exterior construction, small dimensional errors can have major long-term effects. Below are examples that require centimeter-level accuracy.

• Drainage slope: If the slope of an approach or parking area is off by a few centimeters, rainwater may not flow properly and puddles can form.

• Fence and gate positioning: Slight misalignment of fence posts or gate width can cause gates not to close properly or leave gaps, creating functional and aesthetic issues.

• Flatness of tiled paving: Even a few millimeters of uneven height in an entrance approach tiled surface can cause tripping hazards or compromise the finished appearance.

• Boundary with neighboring land: Walls or privacy fences installed on a property boundary must be placed based on accurate site dimensions to avoid encroachment or gaps that cause disputes.

• Interface with existing structures: If the positions of building foundations, existing garden stones, or piping are not accurately known, newly designed decks or flower beds could interfere.

As shown above, exterior design requires millimeter- and centimeter-level accuracy, but surveying with traditional tape measures and spirit levels makes it difficult to completely prevent small errors. Also, paper drawings often fail to convey height information thoroughly, leading to on-site disagreements like “this is different from what we discussed.” That’s where digital capture of existing conditions using 3D point cloud scanning comes in.

スマホで3D点群測量が可能に：LRTKとは？

The recently introduced LRTK (smartphone RTK surveying system) enables anyone to perform high-precision surveying easily without complex equipment. LRTK is a technology that turns a smartphone or tablet into an all-purpose surveying device with centimeter-class accuracy by attaching a compact RTK-GNSS receiver to the device. RTK-GNSS is a method that corrects satellite positioning information to achieve high accuracy; previously, specialized equipment was required, but with LRTK a single smartphone can perform position measurements with global coordinates.

A major feature of LRTK is 3D point cloud scanning. By simply pointing a smartphone camera and walking around the site, you can capture point cloud data that records the surroundings in three dimensions. 3D measurement that once required expensive laser scanners can now be achieved with a combination of a smartphone and an LRTK device. The achievable accuracy is about horizontal ±1-2 cm (±0.4-0.8 in) and vertical ±3 cm (±1.2 in), which rivals professional surveying instruments. Yet the equipment fits in a pocket and is designed for easy on-site portability and use.

LRTK is easy to operate even for people without special training, and a single person can complete surveying quickly. Positioning and point cloud capture are done by pressing a button in an app, and the data is recorded automatically. Captured data can be reviewed on the smartphone on-site and shared with office colleagues via the cloud. This combination of ease and practical accuracy greatly lowers the adoption barrier for exterior work.

現況のズレや高低差も見逃さない：正確な現場把握の利点

When planning exterior renovations or landscaping work, the first priority is accurately understanding the current conditions of the site and structures. Using LRTK point cloud scanning, you can collect detailed data down to every corner of the site and not miss subtle discrepancies between drawings and reality.

For example, in older houses the building’s position or elevation may differ slightly from the original plans. Previously, key points were measured with tapes or laser distance meters, but because the number of measured points was limited, there was a risk of overlooking areas that cause error. With LRTK point cloud data, walls and site shapes are captured with millions of points, so building tilt and distance from boundary lines can be determined accurately.

In addition, the precision of capturing ground elevation differences improves dramatically. Traditionally, levels or water leveling were used to measure heights at several points and infer contour lines, but point cloud scanning captures site undulations as a surface, allowing intuitive understanding of slopes and steps. This enables drainage planning and stair or ramp design that reflect actual conditions.

Furthermore, dimensions of existing structures such as buildings and walls can be accurately obtained. Details affecting design—like the width of an entrance porch or the spacing between carport columns—can be measured directly on the point cloud data. There’s no worry about discovering unmeasured areas later; with a single scan you essentially obtain a “digital copy of the site.”

By accurately capturing the existing conditions with LRTK point cloud scanning, the foundation for planning is solid from an early stage. Designers can concentrate on planning with confidence, and the risk of having to redo work later because “the site differs from the drawings” is greatly reduced.

3D点群データをCAD・ARに展開：完成イメージの共有

High-precision point cloud data obtained with LRTK can be used extensively in subsequent design and proposal processes. Basing work on current-condition data makes visualization of the finished image dramatically easier.

Workflow for using 3D point cloud data in exterior work:

• On-site 3D scan – Use LRTK to convert the existing conditions into point cloud data. Site and building details are digitally recorded.

• Reflecting in design – Import the acquired point cloud into CAD or exterior-design software to create plans that match the site. By referencing the point cloud while adjusting layout and dimensions, interferences and inconsistencies can be resolved during the design stage.

• 3D visualization of the finished image – Generate a 3D perspective (rendered preview) from the created plan. By combining building models generated from the point cloud with newly planned exterior elements, you can realistically portray the post-construction appearance.

• Projecting on-site with AR – Using LRTK’s AR feature, the 3D finished model can be overlaid on the actual site. Viewed through a tablet, a virtual garden or gate appears in the pre-construction space, allowing clients to experience the site as if the work were already completed.

For example, when adding a wood deck and flower beds to a sloped garden, first scan the entire garden and the exterior walls of the house with LRTK. Designing the deck’s shape and height based on that point cloud data allows planning that fits perfectly with the house foundation and window positions. If the 3D preview is displayed on-site with AR, the client can see a virtual wood deck in their own garden. Sharing a finished image that is difficult to convey with drawings alone significantly increases the persuasive power of design proposals.

現場から引渡しまでデータを一貫活用

Accurate point cloud data and AR technology obtained with LRTK can be used across all stages of exterior work. From investigation and design to client explanations, construction, and as-built management, consistent data sharing enables smooth progress.

• Streamlining site surveys: Previously, staff often had to visit sites multiple times to measure details and take photos. With LRTK, you can capture point clouds and geotagged photos in a single visit, effectively bringing the site back with you. If questions arise later, you can check the data rather than return for additional measurements, greatly reducing re-surveying effort.

• Clear explanations to clients: As described above, AR display of 3D models generated from point clouds enables intuitive communication of the finished image to clients. Showing the model on a tablet during meetings makes it easy to visually demonstrate “a wall of this height will be here” or “this is how it will look when you park a car,” increasing client understanding and acceptance.

• Information sharing with craftsmen and subcontractors: Site personnel can also use point cloud data and AR for information sharing. For example, before construction the site point cloud and design drawings can be compared to check details, or chalking-out can be performed while confirming placement with AR. Gradients and height information that are hard to convey by voice or 2D drawings are shared as data, preventing construction errors due to misunderstandings.

• As-built management and records: After construction, rescanning with LRTK allows you to retain 3D data of the as-built condition. Comparing it with design data enables verification of finishing accuracy and quick correction if minor discrepancies are found. Since this data can be stored as records, it is useful for later expansions or maintenance. Digitally archiving the history of exterior work can also raise a company’s level of construction quality control.

LRTK導入がもたらす定量的な改善効果

Introducing LRTK into exterior operations can yield the following measurable improvements.

• Improved surveying and design accuracy: Accuracy of current-condition measurement increases dramatically. Ordinary GPS is said to have errors of about 5-10 m (16.4-32.8 ft), but LRTK reduces the error range to ± several centimeters (cm level accuracy (half-inch accuracy)). Where manual measurement often produces height-direction errors, LRTK can capture the vertical direction within about 3 cm (about 1.2 in). Design based on accurate data reduces misalignments and rework after construction.

• Significant reduction in work time: Because point cloud scanning captures a vast number of measurement points at once, surveying that used to take hours can be completed within tens of minutes. For example, even a 100 m² site can be captured in detail by one person walking around for just a few minutes. As a result, the number of site visits decreases and the overall design period shortens.

• Improved information sharing: Point clouds and geotagged measurement data can be shared via the cloud, speeding communication between site and office and within construction teams. Colleagues in remote locations can immediately view the data and exchange opinions. The need to send drawings by email or explain situations verbally is reduced, improving team communication efficiency.

• Enhanced recordkeeping and traceability: Point cloud data and geotagged photos can be accumulated as digital records and reviewed chronologically. If you save 3D data comparing pre- and post-construction states, you can later verify questions like “What was the ground condition before start?” or “Is the post-construction height as planned?” Storing evidence of exterior work in numbers and data increases external credibility.

• Improved construction accuracy and quality: Narrower gaps between design and site help craftsmen perform work at accurate positions and heights. Visual support via AR and precise guidance for pile-driving locations minimize finishing errors. As a result, the incidence of rework decreases, lowering complaint rates and warranty costs.

スマホ測量の手軽さとコストパフォーマンス

Hearing “advanced technology” may make you think “is it hard to introduce?” but LRTK offers ease of use and cost performance that even small- to mid-sized exterior contractors can readily adopt. The biggest appeal is that high-precision surveying can start with nothing more than a smartphone.

First, operation is intuitive and simple. Attach a dedicated device to a smartphone, press the app’s “start surveying” button, and walk—the simplicity means it can be used without special skills. There is no need to spend much time on training, and you can deploy it on site from the day you introduce it.

Next, costs are much more efficient compared to traditional methods. In the past, extensive 3D surveying required expensive laser scanners or outsourcing costs, but LRTK has greatly lowered that barrier. With a relatively small budget you can equip your company with surveying tools, so the return on investment is high. In addition to reducing labor and outsourcing costs, cutting mistakes also reduces wasteful construction costs, offering indirect economic benefits.

Moreover, because everything is completed with a smartphone and a small device, transporting equipment to the site is easy. Large tripods and many cables are minimized, and one person can survey a small or remote site lightly. The convenience of carrying “one device per person” in a pocket and quickly using it when needed is a strength that previous surveying equipment did not offer.

If you want to differentiate yourself in exterior design, start with smartphone surveying. LRTK is already being introduced in civil engineering and building construction sites, and its convenience is attracting attention. In the exterior field it could become a future standard. 3D point cloud scanning and AR using LRTK are trump cards that dramatically increase accuracy and proposal capabilities. Consider leveraging the latest technology to gain client trust while improving operational efficiency.

3D scanning and AR on your side—why not take the next step to the next stage of exterior design?