# Adjust field of view to non-None volume layer

**URL:** <https://discourse.slicer.org/t/adjust-field-of-view-to-non-none-volume-layer/5292>\
**Category:** Support\
**Tags:** segmentation\
**Created:** [January 7, 2019, 9:59am UTC](https://discourse.slicer.org/t/adjust-field-of-view-to-non-none-volume-layer/5292 "2019-01-07T09:59:05Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![feng](https://avatars.discourse-cdn.com/v4/letter/f/82dd89/32.png) [@feng](https://discourse.slicer.org/u/feng)\
**Post date:** [January 7, 2019, 9:59am UTC](https://discourse.slicer.org/t/adjust-field-of-view-to-non-none-volume-layer/5292/1 "2019-01-07T09:59:05Z")

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Could anyone explain what does non-None volume layer mean?  
I was exporting screenshots and found this button above the view window, “Adjust the slice viewer’s field of view to match the extent of non-None volume layer (bg, then fg, then label)”. Does it mean adjust the view to the middle of images?

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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 7, 2019, 1:15pm UTC](https://discourse.slicer.org/t/adjust-field-of-view-to-non-none-volume-layer/5292/2 "2019-01-07T13:15:31Z")

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Yes, clicking that rectangle button centers the slice view on the image volume.

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**Author:** ![pieper](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/pieper/32/8_2.png) [@pieper](https://discourse.slicer.org/u/pieper)\
**Post date:** [January 7, 2019, 1:43pm UTC](https://discourse.slicer.org/t/adjust-field-of-view-to-non-none-volume-layer/5292/3 "2019-01-07T13:43:51Z")

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The ‘non-None’ language means that if you have a background layer it will fit that, or if there’s no background selected it will pick foreground, etc.