A human arm may be difficult to scan for inexperienced users, mostly due to its small surface and round geometry. However, making a complete scan of the arm is easier than it seems, as long as you follow the simple rules outlined below.
Scanning a straight arm:
1) The optimal pose for a person whose arm is being scanned is pictured below.
This pose provides the Eva with enough surface for tracking, while also leaving enough space between the arm and torso for a complete scan with no blind spots.
2) While scanning, make sure to always keep the torso in the field of view of the scanner. Move around the person in a half-circle motion. Be sure to also cover the inner side of the arm from all angles.
3) If you need to scan the hand as well, make sure that the fingers are as straight and as motionless as possible. Scan the palm from the front and the back, and make a swift scanning motion from below in order to cover the area between fingers.
What to avoid:
If the fingers are bent, it will be very difficult to keep them motionless. This will result in a bad scan.
If the arm is too far out from the body, there won't be enough reference geometry in the field of view and the scanner may lose tracking.
Scanning a bent arm:
1) The optimal pose is slightly different in this case:
Be sure to leave enough space between the arm and torso. This is in order to be able to scan the arm without having the torso obstruct the scanner's field of view.
2) While scanning the arm from below, it is important to keep the torso in the field of view of the scanner. This will help avoid tracking loss.
3) Instead of going around the person, you can also ask the person to rotate. This shouldn't change the shape of the arm nor the body.
4) The tips for scanning the hand are the same as mentioned above - straight motionless fingers, quick scanning motion. When scanning the area between the fingers, be sure to keep a lot of surface in the field of view or the scanner will lose tracking.
Optimal post-processing settings
After scanning the arm (regardless of the position), run the Fine and Global registrations in "Geometry" mode.
Then perform a fusion. Any kind of fusion with its hole-filling set to watertight should produce a decent model.
The torso, that was captured just for the sake of improving tracking, can now be easily removed with a swipe of the eraser tool.
A quick human arm scan, that was done with the Artec Eva scanner, can be downloaded here: https://www.artec3d.com/3d-models/arm
Sample video of the process
A video from our Partner Patrick Thorn shows the capture process of a human arm with the Artec Eva, as well as the post-processing of the scan data.
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