What is 3D Laser Scanning

What exactly is 3D laser scanning and could it be relevant to your digital survey needs.  As with all new technologies it is prudent to familiarise yourself with the basics and then be in a position to investigate further if required.

3D laser scanning technology is sometimes referred to as “terrestrial LIDAR” (Light Detection And Ranging).  Another more informative description is “high definition surveying”.  3D laser scanning starts with a 3D laser scanner – which resembles a cross between a typical surveying instrument and some form of large camera.  The laser scanner is often mounted on a tripod for easy set-up around a site as needed.

The laser scanner emits a narrow laser beam to scan objects of interest and captures 3D co-ordinates on their surface.  A laser scanner tightly sweeps its beam over the surrounding scene, virtually blanketing the selected scene with laser measurements.  As the beam hits surfaces of objects in the surrounding scene, some of the beams laser light is reflected back to the scanner.  The laser scanner has a detector that makes a distance measurement based on the return signal.  By automatically combining these distance measurements with internal angle measurements of the scanners rotating mirrors, a scanner can establish a relative X, Y, Z position in space for each point on a surface that the beam hits (pointcloud).  A laser scanner collects hundred of thousands of pointclouds in just minutes.

When a scanners pointclouds are displayed on a computer the result looks like a dense 3D bit-map image of the surrounding scene.  It can be viewed and navigated much like a 3D model.

Objects within the scene will mask areas behind creating “shadow” regions.  To remove these “shadow” effects, most laser scanning projects require laser scans from different positions in order to capture a full scene or structure.  These scans are then registered together to form a single pointcloud of the scene.

Comments are closed.