How to Interpret a 3D Scan: A Walkthrough for Clients

3D models are close-mirrored replicas, often termed as ‘digital twins’, of real-life objects, places, or structures. 3D scanning has revolutionised how surveyors capture, visualise, and document existing conditions. It offers accurate and reliable insights, saving countless hours of rework on complex projects.

Understanding the full extent of the 3D scan and how to validate it is key to getting the full value from your data. In this guide, we break down exactly how to interpret a 3D scan, what to look for, and how to use it confidently in your next project.

Understanding 3D Data

As professionals in the industry, our jobs go beyond surveying and creating 3D data. It also includes driving value for clients and making data accessible and usable for them.

Raw Point Cloud Data

The terrestrial laser scanner, photogrammetry, and kinematic LiDAR give us point cloud data, which consists of millions of data points representing the surface geometry of your project. Before it’s processed and cleaned, raw point cloud data can often look noisy, messy, or even incomplete at times.

• File types: .E57, .RCP, .RCS, .LAS
• Use case: Ideal for accurate as-built references, clash detection, or integration into CAD/BIM workflows

Processed Mesh or 3D Model

Meshes help connect cloud data points into visible surfaces. They’re easier to visualise and share for design reviews and presentations.

• File types: .OBJ, .STL
• Use case: Concept modelling, visual representation, and inspection overlays

CAD or BIM Outputs

Once modelled, clients usually receive AutoCAD or Revit files. These are structured, editable models built from the initial raw scan data.

• File types: .DWG, .RVT
• Use case: Design development, coordination, fabrication, and renovation planning

Visual Reports or Walkthroughs

Some scanning providers include deviation maps, orthophotos, PDFs, or 3D walkthroughs. This visual data helps non-technical stakeholders view the data interactively and understand its spatial context.

What to Look for in a 3D Scan?

Accuracy and Tolerance

Questions to keep in mind while viewing your 3D scan:

• What is the accuracy level of the data (e.g., ±2 mm, ±5 mm)?
• Were there any control points or benchmarks used to align the data?

Scans aligned to site coordinates ensure data precision and proper documentation.

Coverage and Completeness

Look for shadows, occlusions, or missing data in vulnerable areas such as tight corners and reflective surfaces. A good scanning report should note these limitations, so you know the exact extent of your dataset.

Registration and Alignment

Most 3D scans are stitched from multiple stations. Make sure you zoom in and check for any misalignments or duplicate edges that might impact measurements.

Noise and Outliers

Make sure the data you share is cleaned and filtered with no scattered points or missing details. Over-cleaning can remove useful details, and under-cleaning can distort accuracy. It is essential to strike a balance between the two.

Deviation and Comparison Maps

Review colour-coded deviations carefully. Green usually indicates alignment, and red and blue indicate areas out of tolerance. This data helps identify construction variances early on.

Visualising and Exploring Data

3D Walkthroughs and 360° Navigation

Walkthroughs help you understand spatial data better and move through the data virtually. Measurement tools and hotspots help mark key details, structural deviations, or MEP routing paths.

Cross-Sections and Slice Views

Cross-sections help you cut through the data horizontally and vertically to assess internal alignments and structural measurements.

Overlaying Design Models

Overlay your BIM model on top of the scan to identify clashes or deviations. Transparency tools and section overlays make it easier to visualise how the built environment aligns with design intent.

Colour Mapping and Heatmaps

Colour maps quickly reveal warping, displacement, or deformation across surfaces. They’re especially valuable in structural inspections or retrofits where dimensional accuracy is critical.

From Data to Clarity

Imagine overseeing a project, and the 3D scan reveals data misalignment or structural issues. A 3D scan helps you identify and mitigate challenges before they become hurdles. Informed decision-making is key and is the foundation of an accurate 3D scan.

At South West Surveys, we don’t just deliver accurate scans; we help you read and apply them. Whether you need a walkthrough of your deliverables or expert guidance on integrating scan data into your workflow, our team is here to help.

Book your 3D scan or speak to our specialists today to get the most out of your next project.