accuracy - too much of a good thing?

When it comes to 3D scanning services, accuracy is the main topic. Pretty much everything revolves around it. Why is that? Well it is really the measure of how good a scanner is. A scanner with low accuracy is of limited value unless it has some other features to compensate for that weakness. But if accuracy is too low, at some point it ceases to become a scanner at all. That is why it is critical that a 3d scanning service provider utilize accurate 3D scanners that produce reliable data consistently. Accuracy is actually something that is not easy to achieve. It requires careful engineering, testing, certification and calibration to produce a reliably accurate 3D scanner. Sophisticated customers for 3D scanning services know this and will often ask for the specifications and calibration information on the 3D scanners being used. So let’s look at some specific project examples where customers used 3D scanning services, and indicate what the accuracy requirement for scanning was.

1.       Reverse engineer large ship propeller. The customer had a large propeller from a sea-going vessel. The propeller was about 5 feet in diameter. The required accuracy for scanning was 1mm.

2.       Bullet casing inspection. This customer wanted to scan bullet casings and needed to see how well they were meeting manufacturing tolerances. They needed an accuracy of +/- .001 inches.

3.       Syringe reverse engineering. This customer needed a very high accuracy of .0005”.

4.       A customer needed to verify the location of conduit sleeves that were installed in the concrete at a construction site. The accuracy of this verification needed to be better than 0.25 inches.

5.       A sand casting company needed an accurate CAD model of a cylinder head. The accuracy of the scan needed to be in the range of .01”.

6.       A simulation company needed to scan a jet engine to create a life-size mockup for training purposes. The accuracy requires was in the range of 0.1”.

7.       A customer did a scan of a firearm grip. The accuracy requirement was 0.5 mm.

8.       A customer scanned the cargo bay of a large aircraft. The global accuracy requirement was .050”.

These are just some examples of the accuracy requirements that customers have had for 3D scanning services projects. It is important to specify the appropriate accuracy for each project to ensure that the goals are met without wasting money chasing accuracy that is beyond the minimum required.