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Hello Blender community! After getting help in an earlier post "How can put a mesh into a different position?", I'm stuck again...

I'm trying to find, with the CT facial scan of a patient, the good position for his lower jaw, using his teeth. If I find his dental occlusion (when all teeth are in contact), I find the position.

The problem in blender is that teeth of the lower jaw go through the teeth of the upper jaw If I'm trying to do it manually.... There is always a spot where meshes are overlapping each other.

Before: enter image description here

After manual repositioning, you can see the top of the front teeth overlapping... enter image description here

The idea is to find the position where there is the highest number of meshes from the lower and the upper jaw in contact at the top of the teeth, but which don't join or overlap each other.

So is it possible to use a tool (like grease pencil to mark the meshes?) or an add-on (and precise Align add-on isn't working) to say to blender to find this good position?

Thank you so much for your precious help!

Edit:

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    $\begingroup$ it would be helpful if you could upload a copy of your ~.blend file to a site such as blend-exchange, and provide a link to the uploaded file in your answer. My personal hunch is that the solution to your question lies in manipulating the pivot point of the jaw, but I can't get enough information from you screen shots to make this a definitive answer. $\endgroup$
    – brasshat
    Commented Sep 12, 2015 at 16:37
  • $\begingroup$ In fact, using a pivot point could help me to move the jaws, but if you start from the position I'm looking for with is the position where the teeth statisticly most touching each other. $\endgroup$
    – Dzan
    Commented Sep 12, 2015 at 17:28
  • $\begingroup$ I only want to close the jaw. $\endgroup$
    – Dzan
    Commented Sep 12, 2015 at 17:29
  • $\begingroup$ <img src="http://blend-exchange.giantcowfilms.com/embedImage.png?bid=499" /> $\endgroup$
    – Dzan
    Commented Sep 12, 2015 at 17:33

3 Answers 3

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I don't believe this can be done with precision having only the open-jaw position. For the future, you may try CT scanning both the open and closed positions - then you can overlay the open jaw mesh onto the rest position.

Also it doesn't help that we only have the left side of the jaw to work with in this scan.

But those issues aside, let's try to work with what we have for the sake of this test.

Techniques that may help:

  • Use the Mask Modifier to hide all of the mesh except the teeth. Get everything else out of the way. Use Grow Selection to select the verts in hard-to-reach places, then add them to the Vertex Group that is to be masked in.
  • Set the Origin Point of each object to be on the tooth with the largest surface area, which we know makes contact. That's a good starting point to start making adjustments to location and rotation of the object.
  • Turn on Backface Culling so that you can see (from behind) when teeth are intersecting.
  • Familiarize yourself with all of the rotation and location transform operations in Blender, because you will need to use them to get this even close to being correct.
  • Split your viewport to look at this from at least two different views at once. It will help you assess the position.

How enabling Back-face Culling can help:

Animated GIF demonstrating the intersection of faces, visible after turning on back-face culling

Since I advised learning more about rotation, here are some quick rotation/transform tips:

  • Hitting R twice (RR) will give you a free-orbiting rotation that is often very helpful.
  • Familiarize yourself with the different Pivot types.
  • Knowing all of the Snap methods (ShiftS) will help you get your 3D Cursor wherever you want.
  • Anywhere your 3D Cursor can be, you can set your object's Origin Point to be there using ShiftCtrlAltC) or the button in your Tools Panel.
  • In addition to the standard Global orientation, at least learn Local and Normal as well if you haven't already.
  • ShiftCtrl + Num1, Num3, or Num7 will align your view to the Normal of a selected face.

Here's a .blend with some changes I made. I wouldn't call it accurate, just better than before. I'm not liable for how this is used. Please don't go building anyone's dental implants based on it. ;-)

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  • $\begingroup$ Taking a CT scan with the teeth touching, makes segmenting out the upper and lower teeth very difficult because there is no area between the teeth for the marching cubes/region growing/ whatever technuque. While you could use the sides of the jaws to register the separate meshes, it could still be messy. The other reason not a good idea, it's really unnecessary exposure for the patient. $\endgroup$
    – patmo141
    Commented Apr 3, 2016 at 11:44
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  1. This is a minor improvement on Mentalist's answer. Take an OPTICAL bite registration to scan in centric occlusion. Then picked points and iterative closest point algorithm to align the meshes.

https://github.com/patmo141/object_alignment http://blenderartists.org/forum/showthread.php?332665-iterative-closest-point-algorithm

  1. Attempt to use a physics simulation to pull the teeth together and let them settle. It's difficult!

Other than that, the answers Mentalist gave to assist you in manually aligning are the best.

-Patrick

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I finally succeed by doing it with optical bite registration, and align it in Meshlab software in fact. To difficult in blender. So sad that your Dental Design Tools is no longer available... I find my way in orthognatic, reconstructive free flap surgery and implant by myself. Is it still possible to have your add-on Patrick?

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