Accuracy and resolution dependency

[eli28]

Hello,

Is there an option that a measurement device's accuracy is smaller than its resolution?
I saw a 3D scanner data sheet, and it's written that the volumetric resolution is 0.1 mm while its accuracy is 0.02 mm.

 

[IRstuff]

A 5:1 resolution:accuracy ratio presumably makes reconstruction of surfaces easier, since the data points do not necessarily need to be fitted to a mathematical surface.

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[Compositepro]

IR read the question again. Stated resolution is less than stated accuracy. I'm wondering what is the definition of volumetric resolution (mm is not a unit of volume). Then we also have the somewhat confusing but common nomenclature where high resolution/accuracy is denoted by a lower value.

 

[BrianE22]

Just a guess, but if the linear accuracy is .02 mm in each axis, then the volumetric accuracy might be no better than (1.02)^3 = 1.06 or .06 mm^3. I wouldn't want to be fooled by a display accuracy greater than the measurement accuracy so they limit the display resolution to something a bit worse than .06 so that's why you see .1.

 

[IRstuff]

Stated resolution is less than stated accuracy.

The OP stated otherwise, 0.1 >> 0.02; with a 5:1 ratio, a perpendicular measurement of a flat surface is like to produce at most a couple of values of distance, and most likely, a single value, which makes it easier to determine that it's a flat surface. Note that there's greater than 99% confidence that a 0.1-mm difference is real and reflects a true change in surface height.

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[Compositepro]

0.1 mm is 5 times less resolution/accuracy than 0,02 mm, not greater.

 

[eli28]

Here is a link to the 3D scanner technical data.
Maybe you will understand better:

https://www.creaform3d.com/en/portable-3d-scanner-handyscan-3d/technical-specifications

 

[IRstuff]

I never said the resolution was less than the accuracy; I said their ratio was 5:1 (0.1/0.02), which is consistent with accepted practices in test accuracy ratios (TARs). When you get a change in range of 0.1 mm, there's better than 99% confidence that the change is close to 0.1 mm. Some people possibly want that; while others prefer to process their fuzzy point clouds on their own.

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[eli28]

I am quite confused...is it reasonable to generally claim that a measurement device's accuracy cqn be smaller (better, finer) than its resolution? If the device's detection ability is its resolution, how is it possible that it has accuracy that is better than it?