# negative scale causes problem with volume rendering

**URL:** https://discourse.paraview.org/t/negative-scale-causes-problem-with-volume-rendering/1245
**Category:** ParaView Support
**Created:** [February 7, 2019, 9:16am UTC](https://discourse.paraview.org/t/negative-scale-causes-problem-with-volume-rendering/1245 "2019-02-07T09:16:05Z")
**Posts on this page:** 9
**Page:** 1

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### Author: ![matthieuvitse](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/m/9e8a1a/32.png) [@matthieuvitse](https://discourse.paraview.org/u/matthieuvitse)
#### Post date: [February 7, 2019, 9:16am UTC](https://discourse.paraview.org/t/negative-scale-causes-problem-with-volume-rendering/1245/1 "2019-02-07T09:16:06Z")

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Hi, I need to align several datasets, by rotating and scaling one of them to match the others.

When I apply a -1 scale in the y direction to a Resample to Image data, the volume data is not entirely rendered anymore but only some surfaces remain. See attachments for the before/after scaling.

Any guess on what’s happening or what I’m doing wrong?

Cheers,

Matt

 ![after_scaling](https://discourse.paraview.org/uploads/default/original/2X/9/9d12966b3ffa7d61f8215274a495e2065d11042a.png) ![before_neg_scaling](https://discourse.paraview.org/uploads/default/original/2X/6/68ba41edaa10198c363dd1b996e2bd311aacd505.png)

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### Author: ![matthieuvitse](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/m/9e8a1a/32.png) [@matthieuvitse](https://discourse.paraview.org/u/matthieuvitse)
#### Post date: [February 17, 2019, 5:16pm UTC](https://discourse.paraview.org/t/negative-scale-causes-problem-with-volume-rendering/1245/2 "2019-02-17T17:16:02Z")

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up?

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### Author: ![mwestphal](https://discourse.paraview.org/user_avatar/discourse.paraview.org/mwestphal/32/17_2.png) [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [February 18, 2019, 9:51am UTC](https://discourse.paraview.org/t/negative-scale-causes-problem-with-volume-rendering/1245/3 "2019-02-18T09:51:52Z")

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Hi Matthieu,

Looks like your attachements are missing.

afaik, Resample To Image filter does not support -1 as a parameter for sampling dimensions.

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### Author: ![matthieuvitse](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/m/9e8a1a/32.png) [@matthieuvitse](https://discourse.paraview.org/u/matthieuvitse)
#### Post date: [February 18, 2019, 10:05am UTC](https://discourse.paraview.org/t/negative-scale-causes-problem-with-volume-rendering/1245/4 "2019-02-18T10:05:11Z")

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Hi Mathieu,

attachement was indeed missing, sorry about that. The same thing happens for a direct import of an image volume.

Would adding this support be difficult? it’s quite useful for me as I have multiple volumes coming from multiple sources that do not match, and I may not have access to the pre-process of each volume to change their orientation.

Thanks

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### Author: ![mwestphal](https://discourse.paraview.org/user_avatar/discourse.paraview.org/mwestphal/32/17_2.png) [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [February 18, 2019, 10:14am UTC](https://discourse.paraview.org/t/negative-scale-causes-problem-with-volume-rendering/1245/5 "2019-02-18T10:14:39Z")

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You mean -1 in the transform of the representation !  
Indeed, it does not seems to work with volume representation, definitely a bug.

You are welcome to open an issue on our gitlab : [https://gitlab.kitware.com/paraview/paraview/issues](https://gitlab.kitware.com/paraview/paraview/issues)

FYI, contribution are very welcome.

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### Author: ![matthieuvitse](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/m/9e8a1a/32.png) [@matthieuvitse](https://discourse.paraview.org/u/matthieuvitse)
#### Post date: [February 18, 2019, 10:18am UTC](https://discourse.paraview.org/t/negative-scale-causes-problem-with-volume-rendering/1245/6 "2019-02-18T10:18:54Z")

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Yes, in the transform, I wasn’t clear enough.

OK, i’ll open an issue in the afternoon, thanks for you reply.

What kind of contribution do you mean? in the bug reports or in the bug fixes?

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### Author: ![mwestphal](https://discourse.paraview.org/user_avatar/discourse.paraview.org/mwestphal/32/17_2.png) [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [February 18, 2019, 10:20am UTC](https://discourse.paraview.org/t/negative-scale-causes-problem-with-volume-rendering/1245/7 "2019-02-18T10:20:38Z")

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All are welcome : issue reports, issue investigation, bugfixes and merge requests 🙂

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### Author: ![matthieuvitse](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/m/9e8a1a/32.png) [@matthieuvitse](https://discourse.paraview.org/u/matthieuvitse)
#### Post date: [February 18, 2019, 10:26am UTC](https://discourse.paraview.org/t/negative-scale-causes-problem-with-volume-rendering/1245/8 "2019-02-18T10:26:03Z")

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Sure, i’ll definitely try to get more involved in this. But I guess I’ve got to sharpen my C++ coding skills for the later ones.

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### Author: ![mwestphal](https://discourse.paraview.org/user_avatar/discourse.paraview.org/mwestphal/32/17_2.png) [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [February 19, 2019, 8:57am UTC](https://discourse.paraview.org/t/negative-scale-causes-problem-with-volume-rendering/1245/9 "2019-02-19T08:57:36Z")

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Are you working with the 5.6.0 release ? I see this issue only with a builded master.