3D scanning is the process of analyzing a real object or environment to collect data on the shape and possibly the appearance (e.g., color) of that object or environment. The data collected can then be used to build digital 3D models.

How does a 3D scanner work?

A 3D scanner is uniquely capable of mapping a three-dimensional environment and translating it into a digital 3D model. The distance from each point captured in a given space to the 3D scanner is measured.

This is done by means of a laser rangefinder in the 3D scanner, where a thin laser line is projected onto a physical object. The distance to the object is measured in height, width and depth, and the time difference between turning on the laser line and catching the reflection can be converted to distance. To obtain a three-dimensional model, the object must be scanned from at least four sides.

Polygon model

This information is then digitized and results in a three-dimensional point cloud, where each point is created by a measurement in space. All these points are then connected by lines, resulting in the triangular shapes.

Most 3D scanners have a built-in camera that takes photos of each side of the object being 3D scanned. This photo is then overlaid as a kind of layer (texture) over the point cloud, giving the 3D model the same color as the scanned 3D object. The end result is a polygon model that can be saved in one of the following commonly used file formats: STL, VRML, PLY, OBJ or XYZ. The file can then be edited in CAD software.

The benefits of 3D laser scanning:

1. We can capture the current situation compared to the original construction drawings. In practice, it often turns out that a building has been built differently than it actually is on the drawing. This may already have happened during construction, but also afterwards due to changes that were made later on.

2. The throughput time of the process is in hindsight shorter and more efficient than traditional surveying. Errors are identified earlier on which design changes can be made.

3. 3D laser scanning works quickly and easily. In one working day many rooms and surroundings are measured. A good 3D laser scanner can measure at a speed of at least 2,000,000 points per second.

4. We are on location once and measure everything immediately. This means we have everything available digitally and can digitally measure a 'forgotten measurement' in the point cloud. We simply can't forget anything. We don't have to go back to a location to measure the 'forgotten measurements' again.

5. 3D laser scanning is more accurate than a folding rule, tape measure or distometer. The point cloud is very accurate with a professional scanner while with traditional measuring you depend on the person taking the measurement.

Points of attention for making a 3D scan

1. The 3D laser scanner cannot scan through objects, for example, front walls, glass or water. For the best results it may be necessary to strip the object/building as much as possible after which the correct architectural parts can be scanned.

2. During scanning, a 3D point cloud is displayed of the scanned object, but these are - as the name suggests - only dots. The 3D model must be set up based on this point cloud. This, in turn, involves additional time.

3. It is only possible to scan in dry weather conditions and preferably with as little wind as possible.

4. During 3D-laser scanning you do not have immediate results. Where with traditional measuring you can immediately view and record the desired data, in the point cloud you have to do this afterwards. Measuring something quickly is therefore less easy.