Can you 3D laser scan a shiny surface?
Highly reflective objects such as stainless steel and polished surfaces have always proven a challenge when completing a 3D laser survey. When processed point cloud data can appear to be made up of several layers or misaligned points floating above a plane or surface.
This is due to the way in which light reflects as it hits different types of surfaces. To demonstrate why typically there are two forms of reflection, diffused and specular. The first is associated with a rough or matt surface the latter from a smooth or shiny surface.
With modern laser scanners omitting around 1 million pulses per second a diffused reflection is more likely to reflect a percentage of light back in the direction of the scanner which is then converted into a measurement. However, a specular reflection tends to continue in a similar direction with less chance of being returned to its origin.
When 3D scan data is converted into a point cloud an error or rogue data points may be detected and processed from the reflected surface. This is categorised as “noise” and displayed as points that appear to float above the surface of the scanned object.
This can be cleaned up within the registration software although it can be a time-consuming process.
There are many ways in which smaller individual items can be dulled down such as applying a fine layer of talcum powder or painting the object with a matt paint finish however this can be impractical, especially when working in plant rooms or externally on larger objects.
3D laser scanning & stainless steel
Successful data acquisition can be achieved by making adjustments to the scanner’s resolution and quality along with filters on the software you can minimise the amount of noise created from a 3D laser survey, therefore, producing accurate measure data information without excessive post-survey processing.
“Reflections” is a sculpture created by Rick Kirby and we often used it as a training piece for our scanning teams as the varying reflective surface contain different levels of detail.
It should be noted that it is often better to carry out these surveys without colour especially with external objects as the photographic setting also create distortions with the light. However, as you can see for establishing the correct lighting levels and avoiding direct sunlight this point cloud has been captured in full colour.
If you have a project that requires a 3D laser survey, give us a call or use the link below.