One of the common uses of 3D scanners is for face scanning. Scanning people is quite different from 3D scanning inanimate objects. With our experiences in scanning faces in 3D, here are some things you can do to improve your scanning results:
1. Prepare the model for 3D scanning
- Facial oil can cause people’s skin to be reflective. Reflection will create noise (bounce back) in 3D scans. For this reason, using makeup foundation and applying it to the face before 3D scanning will make the skin tone matte and even out the skin color. Adjusting your projector and camera exposure to match the skin tone will also help improve scan results.
- Tie the subject's hair back with an elastic band or wear a hair cap so that the 3D scanner can have better coverage of the face.
2. Minimize movement as much as possible
People have a tendency to move just by breathing alone. 3D scanning takes a certain amount of time and movement affects scan quality. Less movement is always better. Movement causes noise in the scan results.
To prevent movement:
- Brace your model whenever possible by providing a headrest, a chair with back rest, or by leaning the model's head against the wall. Most people can’t stand perfectly still so having something to lean or brace against ensures you will have cleaner scans.
- The faster the 3D scanner can scan the better the results you will get. 3D scanning at a lower resolution at higher speeds will produce better data than scanning higher resolution but slower. Your model will be less likely move when the scan time is fast. For instance, our fastest 3D scanner is the HDI Base 3D Scanner takes a single scan in approximately 1.5 seconds so it is the best scanner to use for 3D face scanning.
- Let your model know in advance before you hit the scan button. By counting down from 3, 2, 1 your model can have a couple of seconds to get ready by holding their breath and pose.
3. Take several scans and merge them together
While most of us don't have the luxury of owning a multi-head 3D scanner that can gather 3D data from multiple directions, you can still achieve the same effect by using a single-head 3D scanner. To do this you need to capture several single scans from different sides of the face (ie. front, left-hand side, right-hand side). You need to make sure the model keeps still and be in the same position while the scans are being made. After the scans have been captured, align and merge the scans together to achieve a more complete 3D scan.
Do you have any challenges or tips in scanning faces? Please share in the comments.
This blog post was previously posted on Thu, Dec 9, 2010 on 3D3 Solutions blog. LMI Technologies acquired 3D3 Solutions on May 1, 2013.
Posted by Thomas Tong