Reverse non orientated faces all at once

#1

Hello,

is there a way to select non orientated faces and reverse them all at once?

Cheers

Daniel

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#2

Right click on a correctly orientated face and select Orient faces.

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#3

I tryed but it still left me with non orientated faces in the model. Why is that?

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#4

We can only guess without seeing your model.

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#5

orientated faces.skp (408.0 KB)
Here’s the model, I tryed as you said, but still I remain with non orientated faces…

Thanks

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#6

SketchUp can only guess which side should be the outside of a user’s model.
Perhaps the overabundance of unnecessary hidden edges in the model is causing problems.


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#7

The best practice is to tidy up as you go. Correct reversed faces in 3D shapes as they happen. It’ll save you a whole lot of trouble later

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#8

I’m with @Geo and @DaveR on this. SketchUp’s “orient faces” process isn’t perfect and doesn’t always get everything you would think it should. Sometimes the reasons are obscure and you just have to fall back to reversing them one by one.

Best practices to keep the model’s face orientation “clean”:

  • use a garish color for the back of the default material so that face orientation is obvious regardless of lighting/shading
  • fix reversed faces as you go rather than relying on the automated “orient faces” to do them in bulk
  • be wary of small gaps, misalignments and hidden lines; they can cause SketchUp to conclude that two faces are independent and that their orientations are not related or, worse, meant to be opposite.
  • When possible, model objects as SketchUp solids (I say “when possible” because this is not always easy or appropriate) because this will help SU to understand which faces are outward facing.
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#9

Thanks to all, great help!

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#10

It was ONE minute’s work.
View > Hidden Geometry > On
Select the back-facing faces by clicking - using Ctrl to add to the selection.
Then ‘Reverse’ then [context-menu.
I actually use a shortcut key for the reversal as it’s fewer steps…

Note that some of your ‘walls’ and ‘canopies’ are made from a single skin - so these will inevitably have a back-face showing in some views…
Also - hiding a diagonal edge that’s splitting a non-planar skewed wall is no real substitute for making it one flat face in the first place.

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#11

I’ll just add that is is all raw geometry that would be better broken down into groups or components.

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#12

TIG raises an important point that should be added to my list:

  • If as you orbit the model there are directions from which both sides can be seen, it may be ambiguous to SketchUp which way should be front vs back. When possible, add some thickness if there is a direction from which the other side of a face can be seen.
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#13

To make orient faces work make sure each edge only binds a maximum of 2 edges. If an edge binds 3 faces SketchUp cannot know which faces should have a corresponding orientation and for which faces should not.

This simple illustration shows the cross section of an edge binding 3 faces. As you can see the back/front orientation matches between the left and top face as well as between the top and the bottom face but not between the bottom and left face. One of this relation has to be wrong and Sketchup doesn’t know whioch one you’d prefer.

This topic is somewhat related to solid modeling. If each edge binds exactly 2 faces you will get what SketchUp calls a solid (other software often call it closed mesh). For such a geometry each face has one side towards the interior of the volume its defining (typically the blue) and one towards the exterior (typically the white). You don’t need to model everything in solids, especially not when you are just sketching but maybe this explanation helps to backs and fronts of faces.

For the model provided I would typically model each building volume as its own solid. This also allow for them to be moved around separately without sticking to each other in case you’d like to try different dispositions.

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#14

I knew there was an Orient Faces command I’ve used, but I couldn’t remember how to get it to appear. I kept thinking you had to select all the surfaces you wanted to orient.

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[Extension][$] Face Director v1.0.0
#15

Hi I made an extension that might help you accelerate the process of reversing back faces…

Here is the topic link…

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#16

What happens with the faces hidden behind other faces? What will you see if you orbit the camera?

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#17

Hi,

This Extension will only affect faces which are visible by the camera’s view, and will ignore all other faces no matter the orientation of the faces.

If you were to orbit the camera to the other side then the faces will remain unaffected by the plugin. If there were other faces you want to fix then you’ll have to face camera towards them and run plugin once again.

Hope this clears up things.

Best regard,
Renderiza

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#18
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