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how can i calculate volume difference of two objects?

4 REPLIES 4
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Message 1 of 5
merveesekerr
1761 Views, 4 Replies

how can i calculate volume difference of two objects?

I’m a dentist and researcher. In my doctoral thesis, I will look at whether there is a volume difference between teeth images taken with two different intraoral cameras from the same tooth in Meshmixer. I will also look at volume loss after removing the caries. (I looked at similar topics in the forum boolean dif etc but i couldn't solve my own problem)

I know how to make the image solid and calculate volume, but I need to cut and compare images at the same border. Since the cutting line is indented (transition between tooth tissues), I try to cut the two images of same tooth by putting the raw image side by side. There are several mm3 volume differences. But this difference is important for our study. Because it will be understood as the difference between cameras.

In order to explain the problem better, I am sending stl images (1. Cerec cam, 2. itero cam and 3 make solid 1'st cam) as examples.

I would appreciate if you could spare time and help.

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4 REPLIES 4
Message 2 of 5
MagWeb
in reply to: merveesekerr

I get a difference in volume of 2.027mm^3 

 

1. To avoid transparency in the Align tool I use some image SHADER (any but the first 5 will do)

2. I roughly EDIT/Align 2.stl to 1.stl using corresponding SurfacePoints as Source and Destination (Press Shift to click the Destination)

3. I set 1.stl as a target, SELECT the area of interest on 2.stl and run Edit/AlignToTarget. Hit ImproveSolution until 2.stl doesn't move any more.

4. EDIT/Combine both .Stl s.

5. Run PlaneCut below 3g1 on the combined .Stl s.

6. Run SeparateShells on the Stl s.

Now there are 3 comparable objects. To query their volume run Analysis/Stability.

V3g1 = 329.46mm^3

Vstl1 = 397.934mm^3

Vstl2 = 395.907mm^3

Flesh = Vst1 - V3g1 = 68.474mm^3

V3g2 = Vstl2 - Flesh = 327.433mm^3

VDifference = V3g1 - V3g2 = 2.027mm^3

 

Hope that's what you're looking for

 

 



Gunter Weber
Triangle Artisan

Message 3 of 5
MagWeb
in reply to: MagWeb

I attached some Screencast for the workflow above. Might last a while to be displayed...



Gunter Weber
Triangle Artisan

Message 4 of 5
MagWeb
in reply to: MagWeb

Update: The calculation above still adds the error at scanned flesh to the error at the scanned tooth.

So I improved the workflow and git a difference of 1.324 mm^3.

After the PlaneCut step I selected the area of the tooth on a duplicate of 1.stl and generated a group for the flesh region:

Ohne Titel.png

Selecting that group and running Edit/Transform to scale and move it:

 

Ohne Titel 2.png

Accept and select the tooth group to run EraseAndFill(Scale at Zero):

 

Ohne Titel 3.png

Once again duplicate that object C to do  BooleanDifference (1.stl - C) and (2.stl-C). This ends in both teeth with a redundant surface at the bottom. Comparing both volumes gave me 1.324 mm^3.

Ohne Titel 4.png



Gunter Weber
Triangle Artisan

Message 5 of 5
MagWeb
in reply to: MagWeb

Uploaded a Screencast for the second workflow. Might last a while to be displayed here...



Gunter Weber
Triangle Artisan

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