# Segmenting a Entire Slice!

**URL:** https://discourse.slicer.org/t/segmenting-a-entire-slice/10381
**Category:** Support
**Created:** [February 21, 2020, 1:33pm UTC](https://discourse.slicer.org/t/segmenting-a-entire-slice/10381 "2020-02-21T13:33:09Z")
**Posts on this page:** 4
**Page:** 1

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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: [February 21, 2020, 1:33pm UTC](https://discourse.slicer.org/t/segmenting-a-entire-slice/10381/1 "2020-02-21T13:33:09Z")

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The my Micro CT data are reformated with " Fit slice plane to markup fiducials " script. I expected to fill the entire selected slice with Scissor effect by drawing a rectangle. (Same with the paint). However there are areas of unfilled areas which corresponds to the slice below. !

Is this has to do with reformatting ?

 ![2](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/c/c/ccadafe2a8021e1cbf906d53770da3b3411dbe09.png)

 ![1](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/f/4/f4bd31f8ee5db2db860d0698dd9cecef1e7b0725.jpeg)

And when we do the segment growing etc… the final results in the last two slice are not very good becuase of this.

.

 ![3](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/c/4/c4551e6354ff5f8c11d118c576a535f1ebd06986.jpeg)

Is there a way to make a very nice clean cut ? because when we try with segment effects always the changes in this slice will be reflect in the above slice so on…

1. Why is this happening ?

2. Is there a better way of obtaining a clean cut segment of predictable height ? ( we want to make sure the segment height is always 2 mm. )

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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: [February 21, 2020, 1:49pm UTC](https://discourse.slicer.org/t/segmenting-a-entire-slice/10381/2 "2020-02-21T13:49:17Z")

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This looks normal. See explanation here: [https://lassoan.github.io/SlicerSegmentationRecipes/ObliqueSliceSegmentation/](https://lassoan.github.io/SlicerSegmentationRecipes/ObliqueSliceSegmentation/)

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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: [February 21, 2020, 2:19pm UTC](https://discourse.slicer.org/t/segmenting-a-entire-slice/10381/3 "2020-02-21T14:19:30Z")

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Thank you proffesor @lassoan the oversampling (by 2 ) works well.

I do not understand about oversampling. Does this affect volume calculations ?

What does oversampling actually does ?

What are the advantage/ disadvantages of this ?

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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: [February 21, 2020, 2:39pm UTC](https://discourse.slicer.org/t/segmenting-a-entire-slice/10381/4 "2020-02-21T14:39:06Z")

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> [@manjula](#):
>
> I do not understand about oversampling. Does this affect volume calculations ?

It should not significantly affect volume calculations, probably the difference is well below 1%.

> [@manjula](#):
>
> What does oversampling actually does ?

Subdivides the original voxels to smaller ones.

> [@manjula](#):
>
> What are the advantage/ disadvantages of this ?

Advantage is that you can represent finer details. Disadvantage is that it increases memory usage and computation time.