Hey guys,
In my previous post Scanning technologies I’ve covered the two main technologies that are used to 3D scan for 3D printing. Here, I wanted to give you an overview of what should be taken into account when actually doing the scanning with both photogrammetry and light based scanners.
Reflective or transparent surfaces
Avoid! For both light scanning and photogrammetry, reflective and transparent surfaces can be an issue, although for slightly different reasons. In photogrammetry, the issue lies in the software interpreting these surfaces - for the stitching (post-processing of your photos) it needs to assume that all surfaces are equal and it either sees what’s visible behind the glass or what is reflected on the surface.
For the light scanners it’s a matter of hardware, the reflective and translucent surfaces don’t reflect the light as a normal surface, thus the light might simply not reflect back to the camera and capture no data.
Generally, opaque and non-reflective surfaces will get you the best result with both technologies. A quick tip while scanning a person, ask him to remove his glasses, or try with and without to compare the end result.
Lighting
This is one of the most important things to consider when setting up your scan.
For the photogrammetry you will want a well lighted object, just as you would need it for normal photos. Shadows make it difficult to track the object and might result in excessive noise.
Pro-tip: A very good condition for 3D scanning is actually outside, on a cloudy day, because it evens out the lightning just as a good studio. Prefer natural light over artificial lightning.
Lightning is much less of a problem for the laser scanners, as the technology is not based on visual light. However, direct sunlight might cause a lot of “noise” for the software to interpret, thus the same best conditions can apply here. Since the scanning is based on emitting light - they can even be used at night.
You can see how the direct light affects the object in this awesome model 
The Scanning Method
As you need to scan an object from all sides and angles, there’s basically 2 things you can do; you can either spin the object and take pictures from one standpoint, or walk around the object itself and take pictures from all sides.
When walking around with a camera - you need to make sure to take pictures of the whole object (for it not to have any unknown “gaps”). Be careful not to cast shadows on it as well. Try to keep a constant distance between your camera and the object to scan. Another tip, discard all blurry photos, the post processing software won’t be able to correctly stitch them.
If you have a portable laser scanner, the best method is to apply a wave motion - going up and down with the scanner, to capture the whole body, especially the top and the complicated places like under the chin (when scanning a person). Applying the wave motion gives you a good spectrum of reflection which gives you a better image result. Move slowly.
That’s it for now! I will continue this series and dive into different aspects of scanning. Please do leave your comments and critics so we can make this a great resource! Also tell us which topics you would like us to cover and we will.
Happy scanning!
