Laser Scanning is it Magic?
Laser scanning is often perceived as a quick and magical way to recreate CAD data. We have been active in this area since 2004, not only seeing the evolution of the scanners and the software but trying many of the systems and finding out the truth as to what can be achieved.
We have developed our approach to suit our own needs and to interface with the equipment we use to manufacture. This sets us aside from almost every Laser scanning company as they tend only to specialise in scanning, with little or no concept of how the data will actually be used to be able to advise correctly.
Laser scans are full of holes as the laser has to bounce back to the head to produce the image. It can't cope with a sharp edge, as the beam bounces off in any direction, nor can they see into undercuts. The colour can often change the results as well, a red laser beam can be slowed by a black surface and sped up with, of all colours red. its a myth that red is the worst colour. When we first started we were told it absorbs the laser's red beam, in fact quite the opposite is true red is actually not red, but it is reflecting the red spectrum to our eyes therefore it is the best in reflecting the red laser beam.
Specialist software exists to aid this clean up process but it is very time consuming. We prefer a quick scan, and a digital micrometer. then simply redraw the CAD data from scratch with the scan acting as a guide. This process is quick and accurate, but not suited to quality control or inspection when looking for faults, then data cleaning has to be done.
Systems, Processes and Myth's
- Hand Held Scanner A portable system which can be used in the field but works best when fitted to a granite table, quality relies on operator skill.
- Cabinet Scanner This system uses a Laser mounted to an internal arm, the part to be scanned is then placed on a turntable, accuracy is high.
- Large Area Scanner Large area, eg architecture, you can use the Lecia laser system, or a digital camera + special forensic software.
- To the computer The data collected now needs to be cleaned and the holes filled in, as lasers can't see round corners, only in straight lines.
- To much time taken Laser scan images also can't produce sharp edges as the laser bounces off in any direction and not back to the scan head.
- Option 1: Item recreation If your scanning an item for re-manufacture, our approach is to redraw the CAD using the scan as a guide. Recently we scanned and recreated a starter motor in under 2 hrs.
- Option 2: Quality Control If you are scanning because of a fault then the time consuming recreation is the only true way. Typically 2 hrs per MB of scan data is needed, this Dyson part was 12MB taking 3 days.