# Different between Crop Volume and Segmentation geometry

**URL:** <https://discourse.slicer.org/t/different-between-crop-volume-and-segmentation-geometry/14474>\
**Category:** Support\
**Created:** [November 7, 2020, 4:15pm UTC](https://discourse.slicer.org/t/different-between-crop-volume-and-segmentation-geometry/14474 "2020-11-07T16:15:04Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Andreas](https://avatars.discourse-cdn.com/v4/letter/a/ee7513/32.png) [@Andreas](https://discourse.slicer.org/u/Andreas)\
**Post date:** [November 7, 2020, 4:15pm UTC](https://discourse.slicer.org/t/different-between-crop-volume-and-segmentation-geometry/14474/1 "2020-11-07T16:15:04Z")

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Hello all,

what is the difference between the two modules: Crop Volume and Segmentation geometry. (see image)

 ![Different between Crop Volume and Segmentation geometry](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/f/9/f9619d9751c17d7b4f8bc14d67245747ae52719f.jpeg)

Both can be used to adjust the spacing. What exactly is the difference?

best regards

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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:** [November 10, 2020, 9:03pm UTC](https://discourse.slicer.org/t/different-between-crop-volume-and-segmentation-geometry/14474/2 "2020-11-10T21:03:23Z")

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Crop volume crops and resamples _volume nodes_. Segmentation geometry feature is for resampling _segmentation nodes_.

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**Author:** ![bserrano](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/bserrano/32/17034_2.png) [@bserrano](https://discourse.slicer.org/u/bserrano)\
**Post date:** [September 8, 2022, 1:28pm UTC](https://discourse.slicer.org/t/different-between-crop-volume-and-segmentation-geometry/14474/3 "2022-09-08T13:28:44Z")

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Hi,

I am struggling with those two modules as well. Which one is better to achieve maximum accuracy when segmenting (using threshold, local threshold…). Changing segmentation geometry to 1.1 takes much longer than segmenting a cropped volume with 0.9. Why is that?

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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:** [September 10, 2022, 12:13pm UTC](https://discourse.slicer.org/t/different-between-crop-volume-and-segmentation-geometry/14474/4 "2022-09-10T12:13:42Z")

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Crop volume has not much to do with image segmentation. You can use it to prepare your image for segmentation: reduce the image size to the region of interest (to reduce memory need and computation time during segmentation) and make it possible to segment smaller details (by making image spacing isotropic and slightly smaller than the original image).

You can then segment the image using Segment Editor.

Metrics on the segmentation can be computed using Segment Statistics, or specialized modules such as Segment Geometry, Vessel Modelling Toolkit (VMTK), etc.

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**Author:** ![bserrano](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/bserrano/32/17034_2.png) [@bserrano](https://discourse.slicer.org/u/bserrano)\
**Post date:** [September 12, 2022, 11:23am UTC](https://discourse.slicer.org/t/different-between-crop-volume-and-segmentation-geometry/14474/5 "2022-09-12T11:23:41Z")

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OK, thank you. I understand the purpose of crop volume but what is the point of defining a new geometry when segmenting? I understand that the image is not modified when doing an oversampling factor \> 1, so how does the segment change?