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Thin objects with little or no geometry

Any scanner will have trouble capturing a surface that lacks features to track, especially when the surface is too thin to add any. Let’s use a key to show how to make scanning these objects easier.

 

Tracking is the first big problem — the area of the key edges is too small for the scanner to record. The easiest solution is to use a proper background. As long as the scanner “sees” a discrete surface behind the edges, the scan will proceed as it should.

 

The second problem is alignment. The key has similar lengthwise geometry on both sides, and the edges lack features for effective alignment. We’d normally recommend adding texture to the object, but since it’s too small in this case, the best approach is to do an all-around scan in one go. For that you’ll need to hold the key fixed—with pliers, for example—and use a sheet of paper as a background.
 
The third and last problem you may face is when the global-registration algorithm lacks enough data for accurate registration. It goes for the key edges in particular. We already have the sheet of paper as a background to fine-tune the tracking, so we can use it for registration as well. Just remember that the paper should have text or some other markings on it.
 
Our makeshift scanning setup looks like this:

Our setup allows us to scan the key from all sides. It provides enough background for tracking, and the background has rich texture for accurate registration.

 

We also scanned a razor blade using Artec Spider — it was the thinnest object we’ve yet captured. As when capturing the key, one trick is to hold such a thin object above a sheet of paper with colored text, which will be helpful for registration during both 3D scanning and processing.

We used a similar method to capture this dagger: we held it fixed above a paper containing printed text.

dagger_two_views.png 

 

In addition, you may come across tricky cases where you must scan a thin object and would like to collect as much information as possible for future alignment. Our example photo shows a credit card for reference, with the arrows and numbers illustrating the main steps:

  • Scan1: capture a front part of the object and part of the table (meaning any colorful background sufficient for texture tracking).
  • Scan2: capture a rear part of the object together with part of the table.
  • Scans 3 and 4: capture an edge of the object from back to front (or vice versa). You’ll then receive a scan that contains an edge, the object sides and the background. The main thing here is to capture the edge with background from two points.

IMG_20140128_181555_-_Copy.jpg

Now you can align all your captured data, run global registration and enjoy a perfectly scanned thin edge after sharp fusion.

 

We are here to help! If you have any questions or issues, please do not hesitate to contact our team by emailing support@artec-group.com 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.