# mirroring and normals
**URL:** https://discourse.vtk.org/t/mirroring-and-normals/2767
**Category:** Support
**Created:** [March 6, 2020, 11:30am UTC](https://discourse.vtk.org/t/mirroring-and-normals/2767 "2020-03-06T11:30:29Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@andreasbuykx](https://discourse.vtk.org/u/andreasbuykx)
#### Post date: [March 6, 2020, 11:30am UTC](https://discourse.vtk.org/t/mirroring-and-normals/2767/1 "2020-03-06T11:30:29Z")
I have an actor with point normals, and I want to mirror it in X and Y directions. My approach is illustrated in attached python script [mirroring.py](https://discourse.vtk.org/uploads/short-url/prhOU3WfquxmyuhIYkMqJPFhSKr.py) (1.6 KB)
The output
 shows two of the mirrors in black instead of the assigned colors. When I do not generate normals, the colors are OK. I suppose this is due to the normals now pointing inside instead of outside, or the cells having their orientation reversed? When I add a vtkReverseSense to the X and Y mirrors, the image looks OK  .
Is there a method to have the transform fix the normals without having to use vtkReverseSense?
Thanks for your help!
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### Author:  [@lassoan](https://discourse.vtk.org/u/lassoan)
#### Post date: [March 9, 2020, 2:06pm UTC](https://discourse.vtk.org/t/mirroring-and-normals/2767/2 "2020-03-09T14:06:15Z")
To position your actor, you can use origin, scale, and orientation properties of the actor.
As far as I know, UserTransform in the actor is a very low-level API. If you use us then you are expected to take care of all consequences. UserMatrix might work a bit better.
To VTK developers: It would be nice if VTK documentation would clarify what is expected when someone modifies an actor’s UserTransform or UserMatrix.
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### Author:  [@ben.boeckel](https://discourse.vtk.org/u/ben.boeckel)
#### Post date: [March 16, 2020, 5:14pm UTC](https://discourse.vtk.org/t/mirroring-and-normals/2767/3 "2020-03-16T17:14:35Z")
> [@lassoan](#):
>
> To VTK developers: It would be nice if VTK documentation would clarify what is expected when someone modifies an actor’s UserTransform or UserMatrix.
Please open an issue for this; it’s just going to get (more 😕 ) lost here on Discourse.
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### Author:  [@lassoan](https://discourse.vtk.org/u/lassoan)
#### Post date: [March 17, 2020, 11:45am UTC](https://discourse.vtk.org/t/mirroring-and-normals/2767/4 "2020-03-17T11:45:00Z")
Added an issue for improving documentation of these methods - [https://gitlab.kitware.com/vtk/vtk/issues/17807](https://gitlab.kitware.com/vtk/vtk/issues/17807)