Hybrid 3D scanning systems work by combining photogrammetry and structured light methods.
How it works:
Like in a DSLR photogrammetry 3D scanning system, in a hybrid 3D scanning system there are cameras and lights mounted in an array around the subject being scanned. In addition to cameras and lights, there are also projectors that project a pattern on the person being scanned. The cameras in the scanning system take two sets of photographs. The first set of photographs is taken with the projectors turned on while the second photoset is taken with the projectors turned off. These photos are taken in as close succession as possible, usually 150 to 250 milliseconds apart. The photos with the projectors turned on are used to calculate the geometry of the person while the photos with no projection are used for the texture. The big innovation over basic photogrammetry is the photoset with the pattern projected. The pattern blankets the individual with easily identifiable points which helps the photogrammetry software reconstruct high quality geometries everywhere including flat colored materials. Since the pattern makes the geometry reconstruction a lot easier for the software, you do not need to use as expensive a camera sensor as a DSLR sensor, so hybrid systems are only a fraction of the cost of a DSLR photogrammetry scanning system.
Due to the 150-250 millisecond delay between the 2 photos, hybrid 3D scanning systems are not suited for 3D scanning someone if they are continuously moving (ex: action shots or pets that can’t sit still for ¼ of a second). Also, while the reliability of the geometry detail is greatly improved, structured light handheld scanners still produce higher quality geometry.
The post production process for hybrid 3D scanners is the easiest out of all the different 3D scanning technologies. Since the process is instantaneous there is a very low chance of blurring in the 3D scan. You also don’t have to worry as much about deformed geometry as compared to a pure photogrammetry system. The majority of the time spent in the post production phase is spent fixing parts of the texture that didn’t match properly or fixing a part of the geometry that was obstructed in the photographs.
- Quality - Like DSLR photogrammetry 3D scanning systems, hybird 3D scanning systems can also produce very high quality textures with much more reliable geometry data.
- Scanning time – Similar to pure photogrammetry, hybrid 3D scanning systems are very well suited for scanning things that have trouble standing still (people, pets etc.).
- Reliability – Hybrid systems are capable of scanning the greatest variety of people, pets and poses and are most likely to produce usable 3D models.
- Cost – The two most viable technologies for 3D scanning people today are pure photogrammetry and hybrid systems and in terms of cost hybrid systems are far cheaper than DSLR photogrammetry systems.
- Imperfect quality - Hybrid systems fall short of photogrammetry systems in terms of pure texture quality and fall behind structured light handheld scanners in terms of pure geometry quality. The geometry and texture quality is good but not the best.
- Processing time – The hybrid method still suffers from the same photogrammetry processing time limitation though it is not as extreme as a DSLR photogrammetry setup because not as much data is fed into the software. We overcome this limitation at with the Twindom Cloud which allows us to process an unlimited number of scans in parallel and use some of the most powerful servers available. The Twindom Cloud can process a preview scan in as little as 5 minutes and a full quality scan in 2 hours.
Hybrid 3D scanning systems are the newest approach to 3D photography and do a good job of making up for the weaknesses of the other three technologies including cost, reliability and user experience. While they don’t produce the best possible 3D models, the quality is sufficient to produce very high quality 3D figurines making this technology a great solution for the 3D portrait market. Twindom uses the hybrid approach in our Twinstant Mobile scanning system.