October 18, 2017
We recently conducted an interesting survey of Artec customers in which we asked them to describe a challenging 3D-scanning situation. Because some respondents wanted us to provide a typical workflow for capturing human hair using Artec Eva, let's talk about hairstyles. :)
To begin, we usually advise customers to practice the movements from this video tutorial —for example, scanning angles, tilting the scanner, holding the scanner correctly and so on. Applying these tricks to your 3D scanning is always helpful.
Myth busters: hair color
Surprisingly, hair color affects 3D scanning with Eva much less than people think. The popular myth is that Eva has a harder time with dark hair than with blond, but what really matters for the 3D-reconstruction algorithm is the hair structure, such as how fluffy it is.
Long, straight, dark hair is therefore relatively easy to capture, whereas long, blond, fluffy hair requires more techniques for a successful 3D scan.
"4-S" rule for hair scanning
Artec Gold Partner Edwin Rappard created a set of guidelines unofficially called the “4-S rule for hair scanning”:
- Scanning path
- Smooth / Sharp fusion
Let’s review them one by one!
1. Sensitivity should be set to “Extreme” in Scan → Advanced; doing so will help reconstruct as much of the hair geometry as possible while scanning. This rule applies to Artec Studio 11 and earlier; Artec Studio 12 automatically adjusts the Sensitivity parameter.
2. Shoulders/neck can be a reference during your scanning session, so keep them in the scanner’s field view as much as you can. For example, if you capture the top of the subject’s head by using Eva from above and it “sees” the shoulders at the same time, the tracking algorithm will use the shoulders as a reference. As a result, tracking will be faster and more robust, and you’ll be able to successfully capture the head without any tracking loss.
3. Scanning path: use the following approach.
- Start scanning the hair from either the left or right ear.
- Tilt the scanner up and down, but always keep it pointed at the subject’s head.
- As mentioned above, capturing the shoulders/neck at all times is vital.
- Don’t worry if your hair scan has a few small holes. If the scanner captures at least some part of the hair, it’ll successfully reconstruct the shape during postprocessing.
- The most important part of capturing hair is to scan the back of the head and capture as much hair geometry as possible.
4. Smooth/sharp fusion with the “watertight” option is best for 3D-mesh creation.
For example, if you check only one 3D frame, it may seem to add little to the total 3D geometry. When you have several such frames, however, smooth/sharp fusion with the “watertight” option will reconstruct the hair perfectly, even if it’s wavy and fluffy.
Here’s a picture of a single 3D frame from a full scan:
And here are all the 3D frames from the raw scan, selected simultaneously:
Now let’s check the 3D mesh that Artec Studio reconstructed using smooth fusion (the raw scan is on the left and the result of the smooth fusion is on the right):
If none of above helps, you still have several possible workarounds:
- Run a wet hand through the hair before starting the 3D scan (check this video tutorial at 04:00 for more information)
- If the subject agrees, use a little hair spray
- Dry shampoo is sometimes more convenient than hair spray because it’s easily removable with a comb once the 3D-scanning session is complete.
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.