Zero Rework! Pre-Construction Checks for Exterior Work Made Possible with LRTK

In exterior (landscaping) construction, even slight discrepancies between plans and the site often cause "rework," leading to increased costs and schedule delays. This article explains the importance of pre-construction checks for exterior work and how to prevent rework using the latest technology. In particular, by using a solution called LRTK that incorporates 3D scanning and AR (augmented reality), on-site verification accuracy can improve dramatically, and achieving "zero rework" is within reach. On sites with limited personnel and tight schedules, using the latest tools can prevent small oversights from turning into major rework.

LRTK consists of a high-precision GNSS receiver and a smartphone app, integrating on-site 3D scanning, surveying, AR display, and cloud sharing into an all-in-one system.

The Importance of Pre-Construction Checks in Exterior/Landscaping Work

Residential exterior and landscaping work involves many conditions to check, such as interfaces with the building and neighboring environment, ground conditions, and piping. If these conditions are not thoroughly investigated on-site and confirmed before construction, troubles such as "this isn't what we expected" can occur during construction. For example, the planned gate location on the drawings might not match the actual site slope and require rework, or poor coordination with the main building construction may cause unnecessary waiting times. On small sites in particular, seemingly minor oversights can lead to overall rework, so caution is necessary. Traditionally, on-site pre-construction checks involved measuring dimensions with tape measures and levels and comparing them with paper drawings. However, relying on human visual inspection and manual work leaves a risk of missed measurements or errors on complex-shaped lots or sites with large elevation differences.

Thorough pre-construction checks are essential to reduce these risks and ensure smooth construction progress and quality.

Why Rework Happens and Its Costs

Why does rework occur? One reason is insufficient information gathering before construction or mistakes in the design verification stage. If there is a discrepancy between the landscaping drawings and the actual site dimensions, parts may not fit during construction, leading to rework. Insufficient sharing of the final vision with the client can also be a cause. Complaints like "this isn't what I expected" arising from differences in the completed image can lead to post-completion rework, which you want to avoid.

Rework can also result from overlooked underground utilities, boundary issues with neighboring land, or coordination errors with building construction. For example, starting excavation without knowing the location of piping can later require pipe relocation or repair. Neglecting site surveying can lead to misidentifying the site boundary and later having to correct a fence location. When rework occurs, not only do material and labor costs increase, but schedule extensions can damage customer trust. Since exterior work is linked to the handover timing of the building, delays can affect the customer's move-in schedule. In some cases, contractual penalties or additional expense burdens can result, which can be a major blow to contractors. For small and medium contractors, these unnecessary costs and loss of trust can seriously affect business management.

Also, demolishing and redoing completed work places a heavy mental and time burden on site staff and can lower motivation.

The New Norm: Pre-Construction Checks Using Point Cloud Scanning and AR

Recently, the construction industry has been adopting 3D surveying techniques and AR (augmented reality) for pre-construction checks. For example, point cloud scanning using smartphone-embedded LiDAR sensors can convert site topography and surroundings into high-precision 3D data. This enables the site dimension checks that were previously done with plans and tape measures to be performed accurately on a digital 3D model.

Moreover, if you AR-display the designed exterior 3D model on-site, you can confirm the full-scale completed image before construction. Height and depth, which can be hard to grasp from drawings alone, can be intuitively understood by viewing them on-site through AR. For instance, you can check with AR whether the height of walls or fences harmonizes with the surrounding scenery or whether the width of a front approach is sufficient. Using these technologies, potential issues can be identified before construction and stakeholders can share a common understanding.

In the past, using 3D scanning and AR required expensive equipment and expertise, but recently solutions that work with smartphones and affordable devices have emerged, making adoption feasible even for small and medium landscaping contractors. With government initiatives like i-Construction and the promotion of CIM (Construction Information Modeling), the use of 3D data and AR in landscaping is expected to expand further. Improved accuracy of pre-construction checks will significantly reduce the risk of rework after construction.

Example Workflow for Exterior Checks Using LRTK

Now let's look at a pre-construction check workflow for exterior work using the latest tool LRTK.

First, use LRTK during the pre-construction site survey. The person in charge carries a smartphone and the LRTK device, scans the entire site, and obtains high-precision point cloud data. Elevation differences of the site and the positional relationships of buildings and boundaries are converted into 3D data and saved to the cloud in a matter of minutes. The cloud-synced data can be reviewed on the office PC for topography, or imported into CAD software for design adjustments. At the same time, if you use the photo geolocation function to take site photos with position information at key points, you can later review the site details thoroughly in the office.

Next, import the exterior 3D models and drawing data created during the design phase into the LRTK app and try displaying them in AR on-site. Through the smartphone screen, planned gate posts, carports, fences, and other elements are overlaid on the actual site. Because LRTK's AR feature places models based on high-precision coordinates, the display remains stable without drifting as you change viewpoints. This allows you to discover interferences or problems that drawings alone might not reveal. For example, check with AR whether a planned gate post interferes with a swinging door, or whether a carport's height will block a second-floor window. Being able to consider design adjustments on the spot leads to plans that avoid rework.

Furthermore, using LRTK's coordinate navigation feature makes it easy to stand at the exact on-site locations of design elements. Following the smartphone guidance, it will direct you to staking points or foundation positions with precision on the order of a few centimeters, improving the accuracy of layout strings and marking. Completing such design verification by aligning data with the actual site before construction effectively eliminates discrepancies between drawings and the site, allowing you to proceed to construction with confidence.

Additionally, at project completion you can scan the finished exterior with LRTK to obtain 3D as-built data and verify whether construction was carried out according to design. Thorough checks like this ensure robust quality control and provide lessons for future projects.

In practice, one landscaping contractor used LRTK as a sales tool by AR-projecting the planned exterior 3D model onto the customer's site, and customers reportedly found the concrete imagery extremely easy to understand. Sharing data via the cloud among multiple devices so that customers and designers view the same 3D image during meetings also greatly increases the persuasive power of proposals.

Effects of Introducing LRTK: Reduced Rework, Faster Work, and Improved Safety

• Reduced rework: The biggest benefit of using LRTK is the reduction of post-construction rework. By eliminating mistakes and inconsistencies before construction, the occurrence of rework drops dramatically. Also, by using AR at project completion to compare the as-built with the design, last-stage oversights that cause rework can be prevented. Reducing unnecessary material waste also contributes to lower environmental impact. Eliminating rework can improve profit margins.

• Faster work: LRTK streamlines surveying and layout tasks. With machine assistance, accurate data acquisition and marking can be done quickly without relying on the intuition and experience of skilled workers. For example, layout work that used to take half a day may be completed in much less time thanks to coordinate navigation. Moreover, surveying tasks that previously required two or more people can often be handled by one person, improving labor efficiency. With fewer reworks, overall schedules shorten and the likelihood of handing over on time increases.

• Improved safety: Precise pre-construction checks help prevent unexpected troubles during construction. Emergency rework on-site can make the work chaotic and compromise safety management, but proceeding according to plan reduces that risk. Measurements with LRTK also reduce the need to perform risky manual tasks in hazardous areas (e.g., at heights or in high-traffic locations). Additionally, knowing the positions of underground utilities from point cloud and coordinate data can prevent excavation accidents. As a result, overall site safety improves.

• Smoother client explanations: Sharing the completed image via AR greatly simplifies consensus-building with clients. Because they can visually understand proposals at the planning stage, misunderstandings like "this is not what I expected" decrease, reducing post-contract changes and complaints. Reporting progress in 3D during construction increases customer reassurance and helps build trust. Adopting the latest technologies also signals your company's professionalism.

Companies that have introduced LRTK report effects such as "survey time was halved" and "client explanations became much smoother." On another site, thorough pre-construction checks using LRTK resulted in no rework occurring until as-built inspection and successful completion.

Tips for Using LRTK

Finally, here are key points to ensure effective on-site use of LRTK.

• Ensure high-precision positioning: LRTK devices are equipped with high-precision RTK-GNSS, but to realize that performance it is important to use them in environments where satellites can be well captured. Turn the power on in an open outdoor area and wait for several tens of seconds for the positioning mode to switch from Float (approximately 1 m (3.3 ft) accuracy) to Fix (approximately 2 cm (0.8 in) accuracy). Perform point cloud acquisition and coordinate measurements after the accuracy stabilizes to increase the reliability of your survey data. Also remember that the smartphone or tablet used must be connected to the internet for high-precision positioning.

• Data sharing and cloud synchronization: Point cloud data, photos, and coordinate data collected on-site can be synchronized to the cloud on the spot. You don't need to return to the office to copy via USB; you can share data with colleagues immediately after capture. It is easy to review maps and 3D viewers on the cloud or download data for import into CAD software as needed. Real-time information sharing between the site and design department enables swift consideration of design changes.

• Integration of 3D data with design tools: Incorporate point cloud data and coordinate values obtained with LRTK into your design workflow. For example, importing point cloud data into CAD or civil BIM software enables design work that reflects current site conditions. Conversely, uploading rendered images or CAD drawings to the LRTK app for AR display can be used for design checks and client presentations. LRTK supports Japan’s plane rectangular coordinate system, so unifying it with your drawing coordinate system makes comparing site data and design drawings easier. Start with small sites to build in-house know-how and introduce the system gradually.

• On-site operational tips: When using LRTK on-site, manage device and smartphone batteries carefully and carry portable chargers as needed. Under direct summer sunlight screens can be hard to see, so using a tablet or sunshade helps. Mark points you plan to survey in advance, and pay attention to safety when checking AR displays—basic precautions go a long way. Operation of LRTK itself is intuitive, but practicing beforehand will help you avoid confusion on-site and make usage smoother.

After introducing the tool, it is important that all site staff share usage and data application methods and actively try it on-site. You may feel awkward with new technology at first, but with practice it will become a strong ally in your work.

Make Pre-Construction Checks Smart with LRTK’s Simple Surveying Features

The challenge of achieving zero rework directly links to improved site productivity and higher customer satisfaction. Using LRTK’s simple surveying features can dramatically streamline the surveying and verification tasks required for pre-construction checks in exterior work. Because the system is intuitive for site personnel to operate without complex equipment or advanced expertise, it is easy for small contractors to adopt. The era when anyone can quickly and accurately verify sites has begun. Adopt advanced technology on your site and realize smart construction management aiming for true "zero rework."