# TWO .stl file alignment and measurement

**URL:** https://discourse.slicer.org/t/two-stl-file-alignment-and-measurement/8259
**Category:** Support
**Tags:** registration, segmentation
**Created:** [September 2, 2019, 1:10pm UTC](https://discourse.slicer.org/t/two-stl-file-alignment-and-measurement/8259 "2019-09-02T13:10:55Z")
**Posts on this page:** 1
**Showing post:** 5

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### Author: ![manjula](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/manjula/32/80981_2.png) [@manjula](https://discourse.slicer.org/u/manjula)
#### Post date: [April 19, 2021, 4:27pm UTC](https://discourse.slicer.org/t/two-stl-file-alignment-and-measurement/8259/5 "2021-04-19T16:27:11Z")

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> [@seanchoi0519](#):
>
> How do you do. I am a dental student at UQ working on a similar research project for my final year requirement - aligning 2 STL tooth models for endodontic research purposes. I was wondering if you were able to find any methods to do the measurement and the colour map.

Hi,

I have tried virtually all methods available in 3D Slicer for surface registration and found the IGT fiducial registration method, a semi automatic method to be the most useful one.

However, I no longer use any 3D Slicer-based tools for registration as results are subpar and take too much time and uses the ICP registration addon in the Blender which is a fully automatic tool and works wonderfully well.

you can find this add-on in github and install it on Blender. It is very easy to use.

> **[GitHub - patmo141/object\_alignment: picked points and ICP alignment addon for Blender](https://github.com/patmo141/object_alignment)**
>
> picked points and ICP alignment addon for Blender

You can see the discussion I had on this topic, with very useful input from others at,

> [@STL models - Alignment and Volume measurement](https://discourse.slicer.org/t/stl-models-alignment-and-volume-measurement/8364):
>
> Hi, Our Input - 2 STL surface scan models (PreOp and Post Op) - from the 3Shape surface scanner. We have two problems. Need to accurately align the pre and post op surface scans ? (they have fixed landmarks) Need to measure the change of volume in the region of interest ? ( the volume of bone resorption) So far, we have install CMF registration and, as you can see from the pictures the alignment with CMF surface registration is not accurate enough. [PreOperative] W…

**Colour maps**

I use the model to model distance and shape population viewer in the 3D slicer to create the color maps.

**measurement**

What measurements you need ? If you are going to segment the structures then you can use the segment editor statistics to measure. Also there are lots of other measurement tools available but will depend on what you need to measure and using what type of data.

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