STABLE GROUND TRUTH ARTEFACTS FOR MEASUREMENT VALIDATION FOR 3D SCANNERS

3D printed polymer parts (e.g. PA12, PA11 etc) have a high coefficient of thermal expansion (CTE) and can be hygroscopic. In addition, they may change shape/size subtly over time due to internal stress relaxation. The net result of this is that if a part is to be used to validate a measurement apparatus (3D scanners etc) on real world parts with representative optical surfaces, as opposed to test artefacts which are in the majority made of different (stable) materials, there is a challenge to ensure that ambient conditions do not affect the outcome. We propose an approach that uses a stable ‘core’ of material that is then covered with a thin layer of the material under test (‘veneer’)