# So weirdly slicer always erases 1 slice lower... WHY?!

**URL:** <https://discourse.slicer.org/t/so-weirdly-slicer-always-erases-1-slice-lower-why/9697>\
**Category:** Support\
**Created:** [January 3, 2020, 5:18am UTC](https://discourse.slicer.org/t/so-weirdly-slicer-always-erases-1-slice-lower-why/9697 "2020-01-03T05:18:59Z")\
**Posts on this page:** 11\
**Page:** 1

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**Author:** ![NoobForSlicer](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/noobforslicer/32/10900_2.png) [@NoobForSlicer](https://discourse.slicer.org/u/NoobForSlicer)\
**Post date:** [January 3, 2020, 5:18am UTC](https://discourse.slicer.org/t/so-weirdly-slicer-always-erases-1-slice-lower-why/9697/1 "2020-01-03T05:18:59Z")

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![THE PROBLEM](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/1/1/11e6fd8e1cad2e89fce9cd9d550c874ad7548871.png)

There is always a problem, I set everything okay but for some unknown reason, slicer is painting 1 slice lower. Here is the image. Yellow line is my eraser tool. When I click as you can see, it erased one slice lower.

No matter what I do, I can’t get this to work properly.

 ![THE PROBLEM](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/1/1/11e6fd8e1cad2e89fce9cd9d550c874ad7548871.png)

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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:** [January 3, 2020, 6:22am UTC](https://discourse.slicer.org/t/so-weirdly-slicer-always-erases-1-slice-lower-why/9697/2 "2020-01-03T06:22:33Z")

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Let us know if you can reproduce this issue with latest Slicer Preview Release.

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**Author:** ![NoobForSlicer](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/noobforslicer/32/10900_2.png) [@NoobForSlicer](https://discourse.slicer.org/u/NoobForSlicer)\
**Post date:** [January 3, 2020, 8:18am UTC](https://discourse.slicer.org/t/so-weirdly-slicer-always-erases-1-slice-lower-why/9697/3 "2020-01-03T08:18:06Z")

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Yes, I have just downloaded it and tested it.

Same problem persists when all is imported in the newest 4.11 version from 17th 12

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**Author:** ![NoobForSlicer](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/noobforslicer/32/10900_2.png) [@NoobForSlicer](https://discourse.slicer.org/u/NoobForSlicer)\
**Post date:** [January 3, 2020, 8:20am UTC](https://discourse.slicer.org/t/so-weirdly-slicer-always-erases-1-slice-lower-why/9697/4 "2020-01-03T08:20:35Z")

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this has been a common issue to be honest… IT has happened many times with different segmentations.

Sometimes all works okay and sometimes it just acts like this.

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**Author:** ![NoobForSlicer](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/noobforslicer/32/10900_2.png) [@NoobForSlicer](https://discourse.slicer.org/u/NoobForSlicer)\
**Post date:** [January 3, 2020, 8:30am UTC](https://discourse.slicer.org/t/so-weirdly-slicer-always-erases-1-slice-lower-why/9697/5 "2020-01-03T08:30:43Z")

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okay so when i place this number on the red view to .500,  
the slice changes but segmentation REMAINS the same.

Then when I draw it deletes segmentation which I see in a good way.

So I put the segmentation in the transformation and move it half a milimeter down but now segmentation matches only half of the corresponding pixel, and half of it is overlapping the inferior pixel.

I am completely puzzled.  
now if the red is at S: 541.000mm I see it okay and it erases the exact slice of segmentation i see.

However if I move S:541.400m the segmentation changes while the underlying image remains the same and then when I paint the segmentation is not erased but it still erases in the lower segmentatin slice.

This is completely nuts and cofusing.

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**Author:** ![NoobForSlicer](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/noobforslicer/32/10900_2.png) [@NoobForSlicer](https://discourse.slicer.org/u/NoobForSlicer)\
**Post date:** [January 3, 2020, 8:33am UTC](https://discourse.slicer.org/t/so-weirdly-slicer-always-erases-1-slice-lower-why/9697/6 "2020-01-03T08:33:56Z")

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the whole point is that when i approach .500 value the image changes and segmentation remains the same.  
if i add .501 the segmentation slice is still showing the same in the red.

and only when I write .502 the segmentation slice changes as well…

so i am thinking now maybe i should lower segmentation 0.002 down so it will maybe be ok idk…  
I will try

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**Author:** ![NoobForSlicer](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/noobforslicer/32/10900_2.png) [@NoobForSlicer](https://discourse.slicer.org/u/NoobForSlicer)\
**Post date:** [January 3, 2020, 8:54am UTC](https://discourse.slicer.org/t/so-weirdly-slicer-always-erases-1-slice-lower-why/9697/7 "2020-01-03T08:54:01Z")

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this is getting weirder and weirder…

segmentation changes at 0.999  
then I lower it by 0.010

now it changes at 0.990.  
What the actual hell? How is this even possbible?

I literally moved it 0.010 mm down and it got pulled only 9 mm down.

I am baffled

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**Author:** ![NoobForSlicer](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/noobforslicer/32/10900_2.png) [@NoobForSlicer](https://discourse.slicer.org/u/NoobForSlicer)\
**Post date:** [January 3, 2020, 9:00am UTC](https://discourse.slicer.org/t/so-weirdly-slicer-always-erases-1-slice-lower-why/9697/8 "2020-01-03T09:00:17Z")

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Now I completely matched it

both image and segmentation slice change exactly at 0.500 and still the very same problem persists.

It appears to me that nothing can change this problem. the yellow line in Left-right view shows correctly in which slice I am hovering over with eraser tool  
but once I click on it, segmentation is painted on the slice lower than that.

Completely confused

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<div class="post-metadata">

**Author:** ![NoobForSlicer](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/noobforslicer/32/10900_2.png) [@NoobForSlicer](https://discourse.slicer.org/u/NoobForSlicer)\
**Post date:** [January 3, 2020, 9:12am UTC](https://discourse.slicer.org/t/so-weirdly-slicer-always-erases-1-slice-lower-why/9697/9 "2020-01-03T09:12:41Z")

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okay

now it only appears to delete what I see in the red when i am between 0.498 and 0.499

any other number wont work.  
Further more the yellow line now is centered on the border between the two neighbouring slices. Meaning it is not covering only one as it used to before.  
Damn it…

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<div class="post-metadata">

**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:** [January 3, 2020, 1:49pm UTC](https://discourse.slicer.org/t/so-weirdly-slicer-always-erases-1-slice-lower-why/9697/10 "2020-01-03T13:49:13Z")

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Don’t worry, these kind of problems can be addressed quickly if we understand what’s happening. For this, we need to be able to reproduce the issue.

Can you upload an example scene that reproduces this and send us the link? (make sure the data is anonymized) Posting a few screenshots with slice intersections displayed could help, too.

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<div class="post-metadata">

**Author:** ![NoobForSlicer](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/noobforslicer/32/10900_2.png) [@NoobForSlicer](https://discourse.slicer.org/u/NoobForSlicer)\
**Post date:** [January 3, 2020, 4:12pm UTC](https://discourse.slicer.org/t/so-weirdly-slicer-always-erases-1-slice-lower-why/9697/11 "2020-01-03T16:12:44Z")

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Thank you for helping… I will have to anonymize the data and upload.

I haven’t managed to solve it