# Feedback requested: Requirements to place a fiducial

**URL:** <https://discourse.slicer.org/t/feedback-requested-requirements-to-place-a-fiducial/18407>\
**Category:** Development\
**Created:** [June 29, 2021, 8:32pm UTC](https://discourse.slicer.org/t/feedback-requested-requirements-to-place-a-fiducial/18407 "2021-06-29T20:32:19Z")\
**Posts on this page:** 3\
**Page:** 2

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**Author:** ![muratmaga](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/muratmaga/32/83011_2.png) [@muratmaga](https://discourse.slicer.org/u/muratmaga)\
**Post date:** [July 2, 2021, 4:13am UTC](https://discourse.slicer.org/t/feedback-requested-requirements-to-place-a-fiducial/18407/21 "2021-07-02T04:13:02Z")

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> [@tomekcz](#):
>
> In other words, roll back to the old version of the fiduicial placement, which is fast and snappy, but achieve the 3D rotation functionality your group desires by introducing a new Alt-Left action.

This may work for us, @lassoan what do you think?

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**Author:** ![seanchoi0519](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/seanchoi0519/32/10354_2.png) [@seanchoi0519](https://discourse.slicer.org/u/seanchoi0519)\
**Post date:** [July 2, 2021, 7:52am UTC](https://discourse.slicer.org/t/feedback-requested-requirements-to-place-a-fiducial/18407/22 "2021-07-02T07:52:10Z")

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This would be great for me.

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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:** [July 3, 2021, 6:26pm UTC](https://discourse.slicer.org/t/feedback-requested-requirements-to-place-a-fiducial/18407/23 "2021-07-03T18:26:24Z")

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I loved the new mouse behavior and it made the code much cleaner. But I agree that this is not how curve drawing works in most other software and if we don’t have a dedicated continuous line drawing widget then it forces users to pause at each point. Since I don’t have time to make the behavior configurable or create a new continuous drawing mode, I will find some other way to add right-click menu to viewers while preserving the old way of placing points.

> [@jamesobutler](#):
>
> Surface cut benefits from a low number of points required that can then support modifying easily

We could fit a spline to the drawn curve, or drop points at predefined distances, or automatically place a point at each sharp turn. All doable, and would allow faster and more convenient curve drawing on images, but someone would need to invest at least a few days into implementing this. It would be also a good opportunity to introduce a “magnetic” mode, which would snap the drawn curve to the nearest “boundary” (voxel with high image gradient magnitude).

> [@muratmaga](#):
>
> Actually, I just tried with a 3D model of MRHead segmentation (previously I was using a volume rendering), and the interactions are indeed rather slow. For every mouse move, it takes about two seconds for the fiducial to catch up.

This is indeed inconvenient, but it is not related to this discussion. The behavior was the same before. We could store locators for large models in the model displayable manager and use that in the point picker. This would probably make curve placement over large and complex models 10-100x faster, and so drawing curves over complex models would not be delayed. You can start a new topic or feature request on github if you want to explore this further.

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