Reflections

3D laser scanning reflective objects

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 associated with a rough or matt surface the latter from a smooth or shiny surface.  

3D laser scanner and how light reflects from asurface

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 processed from the reflected surface.  This is categorised as “noise” and displayed as points which appear to be floating 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 scanners 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. 

Mechanical design

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 then give us a call or use the link below.

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