STAHLMAN DESIGN
Drafting & 3D scanning for architectural stone
Photogrammetry - 3D models from photos
Photogrammetry is a technique that creates a 3D model from multiple photos that overlap by at least 70%. Differences in perspective allow the computer to calculate the physical geometry, with millimeter precision in some cases.
Capture the physical form
- Helps take virtual measurements of objects
- Practial when you can't return to a job site
- Allows you to preview the final project before ordering the stone
LiDAR - good, but not always better
LiDAR scanners like those on high-end iPhones and iPads use reflected light to capture 3D models with high accuracy. But the sensor is limited to around 1 cm, so LiDAR scans often lack detail that you can get with photogrammetry:
| Technique | +/- | Note |
|---|---|---|
| LiDAR | + | Measurements are accurate right away and do not need to be rescaled |
| LiDAR | + | Better at capturing reflecting or transparent surfaces than photogrammetry |
| LiDAR | – | Model quality is often poor compared with photogrammetry |
| Photogrammétrie | + | The quality and detail is better, especially for close objects |
| Photogrammétrie | – | Cannot handle transparent or reflective surfaces like windows and water |
| Photogrammétrie | – | The model must be rescaled. Not a big deal if you have also taken tape measurements and know how to do it. I always capture with a tape measure in the model so I can double-check that a model is accurately scaled. |