face orientation

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xc22143
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face orientation

Post by xc22143 »

Hello, everyone. Why is the orientation of the face as shown in the pic "Reversed'?
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Shalmeneser
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Re: face orientation

Post by Shalmeneser »

Because there is no file ?
xc22143
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Re: face orientation

Post by xc22143 »

Shalmeneser wrote: Wed Oct 05, 2022 5:06 am Because there is no file ?
What is the meaning? This model is in Stp format and then I opened it in FreeCAD. Now I save it as Fcstd. it is still reversed.
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onekk
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Re: face orientation

Post by onekk »

xc22143 wrote: Wed Oct 05, 2022 6:35 am What is the meaning? This model is in Stp format and then I opened it in FreeCAD. Now I save it as Fcstd. it is still reversed.
"Reversed" mean the normal is facing inward, so speaking for FC it is a "hole".

As it is not a native shape, it is up to you to find why the face is "reversed".

If it is reversed in the original STEP file is "broken by design"

If it is not reversed could be "imported wrong" by FC.

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Carlo D.
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xc22143
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Re: face orientation

Post by xc22143 »

onekk wrote: Wed Oct 05, 2022 7:00 am "Reversed" mean the normal is facing inward, so speaking for FC it is a "hole".

As it is not a native shape, it is up to you to find why the face is "reversed".

If it is reversed in the original STEP file is "broken by design"

If it is not reversed could be "imported wrong" by FC.
Thank you for your reply! However, I can't check if it's due to import or design because there is no operation history in stp file. So is there any method to check it or fix the mistake in the design? Thank you!
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onekk
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Re: face orientation

Post by onekk »

xc22143 wrote: Wed Oct 05, 2022 7:18 am
onekk wrote: Wed Oct 05, 2022 7:00 am "Reversed" mean the normal is facing inward, so speaking for FC it is a "hole".

As it is not a native shape, it is up to you to find why the face is "reversed".

If it is reversed in the original STEP file is "broken by design"

If it is not reversed could be "imported wrong" by FC.
Thank you for your reply! However, I can't check if it's due to import or design because there is no operation history in stp file. So is there any method to check it or fix the mistake in the design? Thank you!
I'm not aware of methods a part from using a method that invert the normal of the face, but this will involve to select the face and use some Python Console commands. I don't remember what is the metod probably something simlar to invert().


try to search "invert normal" on the search box and see if some results make some light.

Regards

Carlo D.
GitHub page: https://github.com/onekk/freecad-doc.
- In deep articles on FreeCAD.
- Learning how to model with scripting.
- Various other stuffs.

Blog: https://okkmkblog.wordpress.com/
wmayer
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Re: face orientation

Post by wmayer »

Hello, everyone. Why is the orientation of the face as shown in the pic "Reversed'?
In general this is hard to say. Sometimes it's the OCC algorithm that produces a reversed face but in many cases the reason is that the shape was already broken before running the algorithm such as invalid tolerances or other anomalies.

In order to get any hint about problems you should run the geometry check from the Part wb on the affected object and its father object.
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Roy_043
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Re: face orientation

Post by Roy_043 »

AFAICT there are no faces with flipped normals in the model. And "Reversed" has a different meaning. It means the Surface the Face is based on has opposite normal(s).
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Shalmeneser
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Re: face orientation

Post by Shalmeneser »

:idea:
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