# How to conduct a 3D CAD comparison to obtain the magnitude deviations with a pre-alignment?

**URL:** <https://discourse.slicer.org/t/how-to-conduct-a-3d-cad-comparison-to-obtain-the-magnitude-deviations-with-a-pre-alignment/26903>\
**Category:** Support\
**Tags:** registration, build, feature, 3d-model\
**Created:** [December 24, 2022, 4:59am UTC](https://discourse.slicer.org/t/how-to-conduct-a-3d-cad-comparison-to-obtain-the-magnitude-deviations-with-a-pre-alignment/26903 "2022-12-24T04:59:29Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![refak\_makeen](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/refak_makeen/32/17797_2.png) [@refak\_makeen](https://discourse.slicer.org/u/refak_makeen)\
**Post date:** [December 24, 2022, 4:59am UTC](https://discourse.slicer.org/t/how-to-conduct-a-3d-cad-comparison-to-obtain-the-magnitude-deviations-with-a-pre-alignment/26903/1 "2022-12-24T04:59:29Z")

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I am currently working on predicting distortion of metal additive manufactured wedge structures. we have made a feasible numerical framework to fabricate components using Abaqus CAE software. In order to validate the framework we are looking into the distortion of as-built fabricated parts. An experimental specimen is as shown in the figure below.

 ![Screenshot 2565-12-23 at 16.49.44](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/d/c/dc5f408e1b6402fd3381d8440747e2cf9a0ace50.jpeg)

Using the Atos core optical camera a 3D stl file of the wedge specimen was obtained and compared using the inbuilt inspection tool. I am getting the deviation results using this software not as a magnitude but the maximum deviation is comparable with the distortion due to residual stresses during the part build.

 ![Screenshot 2565-12-23 at 16.53.31](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/4/7/47aa112116b3dfc43a8a2b8795fb1381bb5023f4.jpeg)

I would like to know if we can find the magnitude distortion of a given surface mesh obtained from an optical camera to make a better comparison with my FEM framework results. Is there any software package, python libraries, to get this task done. Thanks in advance!