# Unexpected dark area in ShadowsLightsDemo (?)

**URL:** <https://discourse.vtk.org/t/unexpected-dark-area-in-shadowslightsdemo/10515>\
**Category:** Development\
**Created:** [January 21, 2023, 3:59pm UTC](https://discourse.vtk.org/t/unexpected-dark-area-in-shadowslightsdemo/10515 "2023-01-21T15:59:01Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![estan](https://discourse.vtk.org/user_avatar/discourse.vtk.org/estan/32/460_2.png) [@estan](https://discourse.vtk.org/u/estan)\
**Post date:** [January 21, 2023, 3:59pm UTC](https://discourse.vtk.org/t/unexpected-dark-area-in-shadowslightsdemo/10515/1 "2023-01-21T15:59:02Z")

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EDIT: Moved topic to the Development category since it’s about one of the official examples. Hope this is OK. Let me know if I should move it back to Support.

Hi folks,

Probably I’m just missing something, but I tried the ShadowsLightsDemo with

```auto
curl -O https://gitlab.kitware.com/vtk/vtk-examples/-/raw/master/src/Python/Visualization/ShadowsLightsDemo.py
python3 ShadowsLightsDemo.py

```

### Output

 ![bild](https://discourse.vtk.org/uploads/default/original/2X/6/6055b51188815301f1554dee63b398bb4f6de3dd.png)

What is the dark area on the top face of the box? It looks like it ought to be illuminated by the light to the left?

Thanks,  
Elvis

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<div class="post-metadata">

**Author:** ![estan](https://discourse.vtk.org/user_avatar/discourse.vtk.org/estan/32/460_2.png) [@estan](https://discourse.vtk.org/u/estan)\
**Post date:** [January 21, 2023, 4:01pm UTC](https://discourse.vtk.org/t/unexpected-dark-area-in-shadowslightsdemo/10515/2 "2023-01-21T16:01:46Z")

</div>

Actually, also wondering about the little light patch on the belly of the sphere.

 ![bild](https://discourse.vtk.org/uploads/default/original/2X/6/637c1868b535ba3e1d94cfbf6f849d1cde3f0154.png)

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<div class="post-metadata">

**Author:** ![estan](https://discourse.vtk.org/user_avatar/discourse.vtk.org/estan/32/460_2.png) [@estan](https://discourse.vtk.org/u/estan)\
**Post date:** [January 27, 2023, 7:58am UTC](https://discourse.vtk.org/t/unexpected-dark-area-in-shadowslightsdemo/10515/3 "2023-01-27T07:58:47Z")

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Noone else who thinks the lighting looks strange? I tried putting a vtkSphereWidget in and moving it around the scene, but didn’t really get any wiser…

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<div class="post-metadata">

**Author:** ![estan](https://discourse.vtk.org/user_avatar/discourse.vtk.org/estan/32/460_2.png) [@estan](https://discourse.vtk.org/u/estan)\
**Post date:** [February 7, 2023, 7:57am UTC](https://discourse.vtk.org/t/unexpected-dark-area-in-shadowslightsdemo/10515/4 "2023-02-07T07:57:58Z")

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Let me know if i should file an issue about this.