Volume Measurement of ROI between two STL meshes

[[Ma...]]

Hello!

I would like to measure the volume of a specific ROI in the upper jaw between an initial scan and a final scan. As I would like to create "stages" for every time point I am interested in selecting this ROI on the CAD file (I have loaded the initial STL as CAD Body and the second scan as STL mesh).

1. I am looking for something like "surface curve " for volume measurement. Surface curve works perfectly and indicates the distance between the STL and the "CAD". However I fail to find something similar for volume measurement.

2. The only way I found is to measure volume via "copy selected points" of my specific ROI or use " construct a surface -> smoothed surface from mesh (No modification)".

However, both I think do not elaborate the volume in between the STL and the CAD scan of my ROI. 

Maybe someone could explain how to measure the volume between two (aligned) scans?

Kind regards

Marc

[[Na...]]

Hello Marc,

you can approximate the volume with the integrated distance (Label "Results-Overview" of a surface deviation):

https://connect.gom.com/display/GKB/Calculation+of+the+integrated+distance

You can also access this value based on a surface distance with a keyword and add to your label.

Regards,
Nanno

[[Ma...]]

Thank you for your reply!!

Am I correct that my previous method using "copy selected points" (of this ROI) and I-inspect -> volume is calculating the volume just against a virtual plane. Does it still calculate against a virutal planeI if I select the measuring method "against reference" or would this be an option?

Does GOM allow me to fuse those two meshes (and fill the space inbetween) because then I would have an idea how "the approximate the volume" method differs from the fusion or my idea of using "copy selected points".

KR

Marc

[[Be...]]

Hi Marc,

use the volume check "only" on nearly watertight meshes (without any holes), e.g. spheres without any boundary curve. A boundary curve is topological a hole, e.g. a mesh which shows a plane has one big hole (due to the boundary curve) even if the mesh which represents the plane has no "holes". If you have only small holes then the volume check is still calculated "in a good quality" because the holes are temporarily closed for the calculation. But if you have big holes then you can't rely how the "holes" are closed: This can fit your expectactions but usually it won't fit your expectations and then the value is semantically "wrong". If you fit them manually then you now what you are doing!

Evaluating the volume between two surfaces mathematically correct is not really well supported in our software (and would need much more interaction/definition from the user because he has to establish a watertight "volume" mesh). Therefore, we only support the approximation  Nanno already mentioned.

Regards,

Bernd