How We Capture a Building — The Leica BLK360 Laser Scanner Explained

What Is the Leica BLK360?

The Leica BLK360 is a compact, high-accuracy laser scanner — and it's the piece of equipment at the heart of every 3D scanning and point cloud survey we carry out at SurveyX.

It looks deceptively simple: a small cylinder about the size of a water bottle, sitting on a tripod. But in a single scan it captures 360,000 measurement points per second, building up a precise three-dimensional record of everything in its field of view — walls, floors, ceilings, structural details, windows, doors and every surface in between.

The result is a point cloud — a dense cloud of millions of individual measurement points, each with an exact X, Y and Z coordinate in three-dimensional space. When stitched together from multiple scanner positions, these point clouds form a complete, millimetre-accurate digital record of the building.

How Does It Work?

The BLK360 uses a technique called time-of-flight laser scanning. The scanner fires a laser pulse and measures the time it takes for that pulse to bounce back from a surface. Since light travels at a known speed, that time measurement converts directly into a precise distance — typically accurate to within 4mm at 10 metres.

The scanner rotates continuously as it fires, capturing measurements in every direction simultaneously. Alongside the geometric data, the BLK360 also captures integrated HDR photography — 360° images from three fisheye cameras that are mapped onto the point cloud to produce a colourised dataset. The result isn't just a set of measurements — it's a photorealistic 3D record of the space that looks as well as measures the building.

What Happens on Site?

On survey day, the scanner is set up at multiple positions throughout the building — typically one position per room, plus additional positions in corridors, stairwells and any complex areas. Each position takes between 3 and 7 minutes to complete a full scan, depending on the settings used.

The number of scan positions depends on the size and complexity of the building. A typical 3-bed house might require 15–25 positions. A large commercial building could require 50–100 or more. Every position is planned to ensure sufficient overlap with neighbouring scans — this overlap is essential for the registration process that comes later.

What Data Does It Produce?

Each scan position produces a raw scan file containing:

• Millions of individual measurement points, each with X, Y, Z coordinates
• Intensity values (how strongly the laser reflected from each surface)
• Three HDR images captured from the integrated cameras

These raw scan files are then transferred to a laptop and taken back to the office for processing in Autodesk ReCap — which is the subject of the next article in this series.

How Accurate Is It?

The Leica BLK360 achieves a ranging accuracy of ±4mm at 10 metres under typical conditions, with a distance range of up to 60 metres. For most building survey applications — floor plans, elevations, sections and BIM models — this level of accuracy is more than sufficient.

For comparison, a skilled surveyor using a laser distance meter and tape measure might achieve ±5–10mm on individual measurements, but those errors can accumulate across a large building. The scanner captures everything simultaneously from a single, fixed instrument position, which eliminates the cumulative drift that can occur in traditional survey methods.

Why Does This Matter for Your Project?

The practical benefit of laser scanning is that the point cloud captures far more information than a traditional measured survey — and all of it at once. Features that might be missed or approximated in a manual survey — irregular wall faces, curved ceilings, complex structural junctions — are recorded in full. And because the raw scan data is retained, additional drawing types can be extracted from the existing dataset at any time in the future, without returning to site.

For refurbishment projects, listed buildings, or any project where accuracy is critical, the BLK360 gives your design team the confidence that the data they're working from reflects the building as it actually exists.