Local VS. Volumetric Accuracy for Self-Positioned Handheld 3D Scanners

In this episode Rapid3D discusses the differences between local and volumetric accuracy as listed on handheld self positioned 3D scanner spec sheets. Curtis discusses how the distance scanned between two measurement points affects the accuracy of the measurement using a precision ball bar and the Creaform HandySCAN Black Elite, and how scanning techniques can be used to optimize the accuracy of any scanner.
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[@forcenine1510]

Of all the vids on you tube, I don't think anyone else has covered this. I have always wondered if the local accuracy rating is relative to the field of view of the scanner.
So basically you can have a scanner with a lower accuracy but a larger field of view, have equal accuracy to a scanner with a higher accuracy but a smaller field of view.
This makes it confusing when comparing scanner specs from different manufacturers.
Thanks for the video.

[@rapid3d170]

Thanks for your comment! Spec sheets can often be confusing and overwhelming, so we try to educate our customers so they can make the best decisions for their individual applications. Every manufacturer reports their specs a little differently, but hopefully this helps you know what to look out for.

[@MaxTheBest97]

Is scanning markers only first, preferably with a spider web pattern, and then preloading the markers before acquisition going to help reducing the volumetric error?

[@samfisherzz]

@3:50 he says “it’s about half a meter so we should expect the measurement to be in 40 micron accuracy”. Shouldn’t it be in 20 micron accuracy?The way I have understood volumetric accuracy, it’s 20 micron plus 40 micron per additional meter. In other words, if your two volumes are under 1 meter apart, the accuracy should be 20 micron. Any additional distance will add 40 microns of inaccuracy per meter.
Please let me know if I am understanding it right.

[@gulliver9822]

20 micro is a scaner error. Half meter ball bar - if u measure it error cannot be bigger than 20+40/2 micro - means 40 micro.
Measure u measured must be within (ball bar +-40 micro). It only means that the bigest error cannot be bigger than +-40 micro.