# SlicerDMRI Tractography Display, Fiber bundle selection with custom function
**URL:** https://discourse.slicer.org/t/slicerdmri-tractography-display-fiber-bundle-selection-with-custom-function/17566
**Category:** SlicerDMRI
**Created:** [May 11, 2021, 8:16am UTC](https://discourse.slicer.org/t/slicerdmri-tractography-display-fiber-bundle-selection-with-custom-function/17566 "2021-05-11T08:16:18Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@simonoxen](https://discourse.slicer.org/u/simonoxen)
#### Post date: [May 11, 2021, 8:16am UTC](https://discourse.slicer.org/t/slicerdmri-tractography-display-fiber-bundle-selection-with-custom-function/17566/1 "2021-05-11T08:16:18Z")
Hi, would it be possible to set up different ways of fiber bundle selection other than ROI?
I would be interested in using a sphere for example, simulating a simple volume of tissue activated and displaying overlapping fibers.
I did this locally by exposing `vtkExtractPolyDataGeometry* ExtractFromROI;` in `vtkMRMLFiberBundleNode.h` and then calling `fiberBundleNode.GetExtractFromROI().SetImplicitFunction()` with a vtkSphere.
Any comments, thoughts? Can give it a try making a PR if you found this feasible.
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### Author:  [@pieper](https://discourse.slicer.org/u/pieper)
#### Post date: [May 19, 2021, 4:10pm UTC](https://discourse.slicer.org/t/slicerdmri-tractography-display-fiber-bundle-selection-with-custom-function/17566/2 "2021-05-19T16:10:36Z")
Hi @simonoxen - yes, it makes good sense to me to generalize this. A PR would be welcome. Let us know if you want to discuss or make this part of a Project Week activity.
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### Author:  [@simonoxen](https://discourse.slicer.org/u/simonoxen)
#### Post date: [May 19, 2021, 4:27pm UTC](https://discourse.slicer.org/t/slicerdmri-tractography-display-fiber-bundle-selection-with-custom-function/17566/3 "2021-05-19T16:27:57Z")
Great! I guess I’ll start looking into it. Project Week also works for me!