# Generate surface normals greyed out

**URL:** https://discourse.paraview.org/t/generate-surface-normals-greyed-out/14607
**Category:** ParaView Support
**Created:** [May 12, 2024, 3:37pm UTC](https://discourse.paraview.org/t/generate-surface-normals-greyed-out/14607 "2024-05-12T15:37:52Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![Lt72884](https://discourse.paraview.org/user_avatar/discourse.paraview.org/lt72884/32/13081_2.png) [@Lt72884](https://discourse.paraview.org/u/Lt72884)
#### Post date: [May 12, 2024, 3:37pm UTC](https://discourse.paraview.org/t/generate-surface-normals-greyed-out/14607/1 "2024-05-12T15:37:52Z")

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I am completely new to cfd and paraview : )

In a basic video tutorial for paraview, one of the steps is to search for a filter called “generate surface normals” so that we can calculate the force on the object.

When i search for it, i see it in the liat but it is greyed out and i can not select it.

Second, what do you guys recommend on youtube for learning paraview?

Thanks

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### Author: ![FEngineer](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/f/5f8ce5/32.png) [@FEngineer](https://discourse.paraview.org/u/FEngineer)
#### Post date: [May 12, 2024, 7:59pm UTC](https://discourse.paraview.org/t/generate-surface-normals-greyed-out/14607/2 "2024-05-12T19:59:34Z")

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You should use the Extract Surface filter first.