Metrology is not about producing visually convincing geometry. It is about proving whether a part lies within acceptable deviation from nominal design. Different 3D measurement technologies serve different scales and tolerance targets.
1. Photogrammetry
Photogrammetry reconstructs geometry from multiple images and works very well for large objects. It offers strong relative accuracy over long distances and is especially useful when targets can be placed and the work volume is large.
2. Laser triangulation
Laser triangulation scanners provide very high absolute accuracy for small and medium-sized parts. They are ideal for dense surface detail, tight tolerances and fine inspection tasks, but their working volume is limited.
3. Comparative view
Photogrammetry scales well to large structures, while triangulation excels in close-range precision. In many industrial cases, both technologies are complementary rather than competitive.
4. Tolerance management in industry
Inspection software compares measured data to nominal CAD and visualises deviation through colour maps. GD&T-relevant characteristics such as flatness, cylindricity and perpendicularity can then be assessed against specification.
Conclusion
The correct measurement technology is selected from the required tolerance, the object size and the environment. Good metrology is the discipline of proving fit, not merely capturing shape.