# Segment overlap versus 3D view

**URL:** <https://discourse.slicer.org/t/segment-overlap-versus-3d-view/45984>\
**Category:** Support\
**Created:** [January 29, 2026, 2:30pm UTC](https://discourse.slicer.org/t/segment-overlap-versus-3d-view/45984 "2026-01-29T14:30:05Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Hannnonk](https://avatars.discourse-cdn.com/v4/letter/h/b5a626/32.png) [@Hannnonk](https://discourse.slicer.org/u/Hannnonk)\
**Post date:** [January 29, 2026, 2:30pm UTC](https://discourse.slicer.org/t/segment-overlap-versus-3d-view/45984/1 "2026-01-29T14:30:05Z")

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Two segments.

3D view when segments overlap, and larger segment (segment 1) is 50% transparent:

 ![1](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/8/d/8dd64250072bb1a1aa007d8c970e587a2bc44414.jpeg)

3D view when smaller segment is subtracted from larger segment (segment 1). Larger segment is 50% transparent:

 ![2](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/a/f/af791eb7b20202b83d145ceec64011ea0b69f116.jpeg)

Why do the opaque bands appear. Is it possible to remove these without expanding the smaller segment to create some overlap?

thx

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**Author:** ![cpinter](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/cpinter/32/7995_2.png) [@cpinter](https://discourse.slicer.org/u/cpinter)\
**Post date:** [January 29, 2026, 4:22pm UTC](https://discourse.slicer.org/t/segment-overlap-versus-3d-view/45984/2 "2026-01-29T16:22:10Z")

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Unfortunately there are issues with rendering semi-transparent triangle meshes especially when shadows are enabled. Do you have shadows enabled? If so, what does it look like when you turn it off?

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<div class="post-metadata">

**Author:** ![Hannnonk](https://avatars.discourse-cdn.com/v4/letter/h/b5a626/32.png) [@Hannnonk](https://discourse.slicer.org/u/Hannnonk)\
**Post date:** [January 29, 2026, 4:35pm UTC](https://discourse.slicer.org/t/segment-overlap-versus-3d-view/45984/3 "2026-01-29T16:35:54Z")

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If that is the “shadow visibility” check box obtained in the upper left, then when it is on it is worse, but the above example was with it “off”

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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 29, 2026, 5:38pm UTC](https://discourse.slicer.org/t/segment-overlap-versus-3d-view/45984/4 "2026-01-29T17:38:04Z")

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The “z fighting” rendering artifact that you see may be avoided or reduced by making both segments somewhat transparent. Even making segments a little bit transparent, such as opacity=99% instead of opacity=100%, may make a difference.