October 18, 2017
Our team has recently conducted an interesting survey among Artec clients, one of the questions was to describe a challenging 3D scanning situation. Since some clients asked to provide a typical workflow for 3D scanning human hair with Artec Eva, let's talk about capturing hairstyles :)
As a start, we usually advise to practice and to repeat the movements from this video tutorial, for example, scanning angles, tilting the scanner, hold the scanner correctly, etc. Applying these tricks to your 3D scanning case is always very helpful.
Myth busters: hair colour
Surprisingly, hair color does not influence 3D scanning with Eva as much as people usually think. The popular superstition is that dark hair is more complicated for Eva scanning than blond one, but what really matters for 3D reconstruction algorithm is the hair structure, for example, how fluffy the hair of a scanned person is.
So long straight dark hair can be relatively easily captured, while long blond fluffy hair will require more techniques to apply to be successfully 3D scanned.
"4 S" rule for hair scanning
Artec Gold Partner Edwin Rappard once created the set of rules which is unofficially called "4-S rule for hair scanning":
- Scanning path
- Smooth / Sharp fusion
Now let's check them one by one!
1. Sensitivity should be set to "Extreme" in Scan → Advanced, it will help to reconstruct as much geometry of the hair while scanning as possible. This rule is applicable for Artec Studio 11 and lower; in Artec Studio 12 Sensitivity is adjusted automatically.
2. Shoulders/neck can be used as a reference in your scanning session, so keep them in scanner field view as much as you can. For example, if you scanning the top of the head by pointing the scanner from above and Artec Eva "sees" the shoulders at the same time, tracking algorithm will use shoulders as reference. As the result, tracking will be faster and more robust and you will be able to successfully capture the head without any tracking loss.
3. Scanning path:
- Start scanning human hairstyle from the left or right ear.
- Tilt the scanner up and down, but always keep scanner pointed at the head.
- As mentioned above, it is vitally important to capture shoulders/neck at every moment of scanning.
- Do not worry, if you have some small holes in your hair scan. If scanner captures at least some part of hairstyle, then its shape will be successfully reconstructed during post-processing.
- The most important issue in hair scanning is to scan back of the head and capture as much geometry of the hair as possible.
4. Smooth/sharp fusion algorithm with "watertight" option should be used for 3D mesh creation.
For example, if you check only one 3D frame, it may seem that it does not add much in terms of total 3D geometry. However, when there is a set of such frames, then the smooth/sharp fusion with the "watertight" option will reconstruct the hairstyle perfectly, even if the hair is wavy and very fluffy.
Here is a picture of a single 3D-frame selected out of the entire scan:
Here are all 3D frames of the raw scan selected simultaneously:
Now let's check the 3D mesh that was reconstructed by the smooth fusion (raw scan is on the left; the result of the smooth fusion is on the right):
If nothing of above helps, there are still several possible workarounds:
- Run a wet hand through the hair prior to the 3D scanning session (check this video tutorial at 04:00 for more information)
- If allowed, use a little bit of hairspray
- Dry shampoo is sometimes more convenient than hairspray because it can be easily removed with a comb after the end of a 3D scanning session.
We are here to help! If you have any questions or issues, please do not hesitate to contact our team by emailing firstname.lastname@example.org or by clicking on "Ask Support" button on the upper part of the screen. We will always be happy to assist you and will get back to you as soon as we can.