# How to find a default colorbar unit or calibrate in mm

**URL:** <https://discourse.slicer.org/t/how-to-find-a-default-colorbar-unit-or-calibrate-in-mm/22501>\
**Category:** SlicerCMF\
**Created:** [March 14, 2022, 4:19pm UTC](https://discourse.slicer.org/t/how-to-find-a-default-colorbar-unit-or-calibrate-in-mm/22501 "2022-03-14T16:19:57Z")\
**Posts on this page:** 5\
**Page:** 2

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**Author:** ![Lexus\_H](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lexus_h/32/4110_2.png) [@Lexus\_H](https://discourse.slicer.org/u/Lexus_H)\
**Post date:** [March 17, 2022, 2:00am UTC](https://discourse.slicer.org/t/how-to-find-a-default-colorbar-unit-or-calibrate-in-mm/22501/21 "2022-03-17T02:00:17Z")

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I have segmented model 1 (pre) model 2 (post) and registered segmentation (both models). what data goes in each blank for logical effect under the segment editor module in order to substract model 2 from model 1?

Do I keep the segmentation in gipl format or change it to stl?

Thanks

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**Author:** ![Lexus\_H](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lexus_h/32/4110_2.png) [@Lexus\_H](https://discourse.slicer.org/u/Lexus_H)\
**Post date:** [March 17, 2022, 2:02am UTC](https://discourse.slicer.org/t/how-to-find-a-default-colorbar-unit-or-calibrate-in-mm/22501/22 "2022-03-17T02:02:03Z")

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> [@lassoan](#):
>
> If it the automatic scalar range is up to -5 then it means that the maximum distance in the entire mesh is 5mm.

So then is it ok for me to write in the manuscript that each mm in mesh corresponds to 2 mm in the actual data (sample)?

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**Author:** ![lassoan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lassoan/32/13_2.png) [@lassoan](https://discourse.slicer.org/u/lassoan)\
**Post date:** [March 17, 2022, 2:14am UTC](https://discourse.slicer.org/t/how-to-find-a-default-colorbar-unit-or-calibrate-in-mm/22501/23 "2022-03-17T02:14:55Z")

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> [@Lexus\_H](#):
>
> I have segmented model 1 (pre) model 2 (post) and registered segmentation (both models). what data goes in each blank for logical effect under the segment editor module in order to substract model 2 from model 1?

You select the larger segment (without bone loss) in the segment list at the top, and you select the other segment in the segment list in the `Logical operators` section.

> [@Lexus\_H](#):
>
> Do I keep the segmentation in gipl format or change it to stl?

You would work with binary labelmap representation, which is usually stored in nrrd files.

> [@Lexus\_H](#):
>
> So then is it ok for me to write in the manuscript that each mm in mesh corresponds to 2 mm in the actual data (sample)?

Maybe what I wrote was misunderstandable because of using signed distance in the example. To make it clear: length unit of the world (a.k.a. RAS or renderer) coordinate system is mm. If distance is 1 that means the distance is 1mm.

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**Author:** ![Lexus\_H](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lexus_h/32/4110_2.png) [@Lexus\_H](https://discourse.slicer.org/u/Lexus_H)\
**Post date:** [March 17, 2022, 2:56pm UTC](https://discourse.slicer.org/t/how-to-find-a-default-colorbar-unit-or-calibrate-in-mm/22501/24 "2022-03-17T14:56:56Z")

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I uploaded pre/post nrrd files then what do I put on segmentation on top then master volumne and then how do I turn oon logical effect? once I select substracct how do I select post nrrd file? After hitting apply then where do I get a result?  
thanks  
Do you have a video for it?

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<div class="post-metadata">

**Author:** ![Lexus\_H](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lexus_h/32/4110_2.png) [@Lexus\_H](https://discourse.slicer.org/u/Lexus_H)\
**Post date:** [April 12, 2022, 3:03am UTC](https://discourse.slicer.org/t/how-to-find-a-default-colorbar-unit-or-calibrate-in-mm/22501/25 "2022-04-12T03:03:12Z")

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Please help me to determine corresponding points between two models so I can measure the distance between two corresponding points. Also, do I need to use one model as source and registered model of two source and target models so I can get a color map along with that?

Thanks,

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