face flip

[remon_v]

hey I'm new to vray and SU... so I watched some tutorials and I nodiced they face flip before applying a material? What's the use of flipping faces??

Ramon

[stevebo]

Re: face flip

I would also like to know! ;D

[Jackson_cg]

Re: face flip

To produce correct results most render programs require normals (fronts of faces) to be consistently orientated outwards, i.e. visible to the camera. Switch to monochrome view mode in SU to see which direction normals are facing (by default blue is back, cream is front). Incorrectly orientated normals often cause errors such as glass, translucency and fog being incorrectly calculated or disappearing faces in renders, so it's one of the most important things to look out for when using components (especially from 3D Warehouse) or other people's skp files. In the case of car components for example, it may take an hour or more just to correctly orientate normals in a poorly constructed model. When building a model I always work in monochrome mode to ensure that all normals are orientated correctly as I go along.

[stevebo]

Re: face flip

Thanks Jackson!

Strange how Sketchup sometimes gives you different normals. I make faces and sometimes it's blue and sometimes cream. At least now I know what they mean!

[remon_v]

Re: face flip

Oke I got a model with glass, form the outside it's oke.... the front side of the face, if I make an interior render with the same model (with the backside of the glass face) it doesn't look normal... a bit blueish. How to fix this?

[Jackson_cg]

Re: face flip

Apply the glass material to the back side of the face.

[remon_v]

Re: face flip

it's the same face so it's already got the glass material... but it's a blueish when rendering the interior and when rendering exterior it looks fine... if u don't get what I mean I will post a pic tonight when I'm home.

[Jackson_cg]

Re: face flip

It doesn't matter what material you have applied to the face, or even how it looks in SU, you have to actually apply the glass material to both sides of the face in SU (Mattheu Noblet's "Remove C-G Materials" ruby script does this automatically). Either that or it just sounds like you've not reduced the opacity enough? :-\ The only other thing I can think of that causes a difference between how one side of a single face glass appears compared to the other would be if you'd forgotten to remove the refraction layer.

[thomthom]

Re: face flip

I wonder if there is a bug that some times crops up that will render back faces blue even though they shouldn't...

[remon_v]

Re: face flip

the opacity is white so it isn't that ..... I'll have a look tonight, and I'll will run the script