Flipping Normals

[arobbert]

I work with many models that are created in AutoCAD. Sometimes the faces are facing the wrong way and don't render correctly in Vray. I've turned force 2 sided with no affect. It gets to be a very tedious process on large models. Does anyone knhave any tips for speeding this up. If I could just select a group of faces and make them all face the same way it would be helpful.

[Morbid Angel]

take your object and go select element under editable mesh and select your entire object's faces. scroll down to surface properties, there is some option there for the normals, one is to flip selected, the other is to unify selected, which would make all normals face one way, if they all become faced inwards then you can use flip to reverse them.

[arobbert]

Thanks, I know about unify but it doesn't make the all face the same way. Mabye there is a way around this. It's only a problem with Vray mats which I've been trying to use more because they are faster. I get faces that won't render isn't there some way to make them two sided?

[Morbid Angel]

well by default vray mat is double sided. However imported meshes can be problematic with normals like that. Unfortinantly I cant suggest anything else, exept if you have access to maya you could import it there and use mayas normal tools to unify the normals, they work much better then max's

[arobbert]

MMMM, I wonder if there are any plugins that might help?

[Morbid Angel]

if this is some object which you need fixed I could look at it in maya and fix it up. But unfortinantly I dont think there are tools to flip normals which can be external for max.

[arobbert]

Thanks for your offer. This is something I'm looking at more for the long term as part of my work flow, so it's not any particlular object.

[timmatron]

Normals have been a huge problem for me lately. When I worked for myself I would always model with autocad solids. Solids are great because the normals always face out. But since I started working at StudioAMD, I've noticed its become quite a pain because they have always modeled everything in surfaces. Rendering 2 sided is fine, but as soon as you need to make a reflective material on objects with flipped normals, you are out of luck, and have to manually start flipping faces.

Would it really be that hard to overcome this problem, either within Vray, or Max itself?

[arobbert]

Yeah, It's fine if you don't use reflections. Unfortunatly most materials need reflections.

[instinct]

What works mostly is creating a doublesided Material and add your Material to both the Front- and the Back-Material....should do the trick.

Thorsten

[nvanherpt]

i had this last night. the sheer brute force method, to be used as little as possible, is to apply a shell modifier to the meshes. works for me but luckily the model was small and i had enough ram.

[panthon]

If u file link the autocad object instead of importing it, the model tends to come cleaner.

[dgsantana]

Also AutoCAD models tend to not be very "weld", so you should try to weld all the vertices (say with a precision of 0.001 or so depending on the scale). After that the elements tend to really be elements (many times they appear as isolate faces/polygons). Then you can use the unify and flip. Of course this tend to be a tedious job if the model is always changing (happens to us alot), has the edit mesh modifier gets all screwed up after a new reload. I now convince my boss to let me model part of the models in max so that there is more control.

Best regards
Daniel Santana

[dimo]

Hi,

If your material is double sided and you turn on "Force Two-Sided" in the rendersettings the reflections should be right.

Best Regards,

Dieter

[timmatron]

What works mostly is creating a doublesided Material and add your Material to both the Front- and the Back-Material....should do the trick.

Thorsten

Hey that seems like a pretty good idea. Have you had any observations on how it affects the rendering speed and ram usage?