# How to quantify the measurements obtained from the vtk file

**URL:** https://discourse.slicer.org/t/how-to-quantify-the-measurements-obtained-from-the-vtk-file/11874
**Category:** Support
**Created:** [June 5, 2020, 8:08am UTC](https://discourse.slicer.org/t/how-to-quantify-the-measurements-obtained-from-the-vtk-file/11874 "2020-06-05T08:08:02Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![danila](https://avatars.discourse-cdn.com/v4/letter/d/0ea827/32.png) [@danila](https://discourse.slicer.org/u/danila)
#### Post date: [June 5, 2020, 8:08am UTC](https://discourse.slicer.org/t/how-to-quantify-the-measurements-obtained-from-the-vtk-file/11874/1 "2020-06-05T08:08:02Z")

</div>

Hi 3DSlicer experts,

I am working on a new project.

My first goal is to quantify the change of a jaw before and after an orthognathic surgery (therefore comparing the pre and post CBCT).

Following the tutorial I found on the DCBIA team website, I made the segmentation of the anterior skull base at t0 and t1 with the ITK-SNAP software.

 ![immagine 1](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/3/a/3aad3db73a45cd7102c0a680cc2a28f92a356af2.png)

Then I do the landmarks approximation about the two scans with Slicer and subsequently the recording performed on voxel relating to the skull base (using: basaline scan - T1; basaline segmentation - segmentation of anterior skull base at T1; follow-up scan - T2landmarks; follow-up segmentation - segmentation of skull base at T2landmarks).

 ![immagine 2](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/e/6/e6e2dd86a1c38f3217b6d4398fd2f053a11ba19f.jpeg)

After the registration I have segmented the first mandible on the t1 scan and the second mandible on the t2 scan obtained from the voxel recording. Then I transformed the segmentations of the two mandible into 3D surface models. I uploaded the two models on Slicer and I apply the module “model to model distance”:

Choose file (s) to add:  
Modelmandible\_T1.vtk and Modelmandible\_T2.vtk

Model to model Distance:  
Parameter set: Create new CommandLineModule  
Source Model: Modelmandible\_T2.vtk  
Target Model: Modelmandible\_T1.vtk  
VTK output file: Create new model  
Distance:  
If i choose corresponding\_point\_to\_point the message that appears is this

 ![unamend 5](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/9/3/9386d297e096c5566c82782840716c7578f4031f.jpeg)

Instead choosing signed\_closest\_point

 ![immagine 4](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/5/e/5e208f1dc2dd32060dd82b6f403f47ca380431cc.png)

I save the vtk file that I get from this last operation renamed “color map.vtk”.

I open the shape analysis view module and choose “color map.vtk”

 ![immagine 5](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/0/9/0966700bebbc214e1a13d7d9bb49ec5dfefbb5de.png)

My question is how to quantify the measurements obtained from the vtk file, after using the model to model distance extension.

The second goal of my study is to compare the post-operative CT with the virtual planning made with the Simplant software, which allows you to export the STL file of the project.

I hope you can help me