Flipped Faces!

[eyepiz]

Hello,

I typically have to import and render a lot of AutoCAD geometry, normally it's crappy exports from Pro-E or solidworks ect... So I get some nasty geometry. I usually clean it up as much as possible, however my biggest issues is Flipped Faces there are hard to spot and usually dont get caught until I'm rendering the final high res shots. Is there any option that is similar to the 2-sided option in the standard materials? so that the faces looks in the same way regardless of what side the camera rays hit it?

The double side option that is on by default in the vray materials do not seem to do anything...or am I missing something?

I would appreciate any advise.

Thanks

Eric

[cheerioboy]

I always thought that as long as you have 'Force back face culling' ticked off in the render rollout, then v-ray would render both sides either way. But maybe the geometry is affected in strange ways depending if the faces or flipped or not..

[glorybound]

I usually put a lightmap, using a dirtmap, into a material override. I turn off light, camera exposure, GI, and it reveals the flipped normals within a few minutes.

[cheerioboy]

You can also go into the display tab, select the object, and turn off 'backface cull' so that you see through the flipped faces. If you wanted to hunt them down and flip them manually.

[eyepiz]

I usually put a lightmap, using a dirtmap, into a material override. I turn off light, camera exposure, GI, and it reveals the flipped normals within a few minutes.

Good tip!...I'm going to give that go....do you change any parameters in the dirtmap?

Thank you!

[glorybound]

just in case you didn't know, if it is an editable mesh, you can tick the show normals button.

[Syclone1]

I use Solidworks models here all the time and for the most part they are a serious PITA

I sometimes find that the following works for normals being messed up:

Under edit mesh select all the Polygons of the object
detach the selected Polygons to a new object
delete the empty old object
select all the Polygons again of the new object and hit unify normal mode and usually that will help to fix flipped normals.
I dont know why making the new object works yet trying to edit the original doesnt but its a good workaround to keep from rebuilding parts in max.

I usually have a lot of small issues like that using the okino plugins which kinda sux. The NPower solidworks importer I rarely have any issues with except that its not good for importing large assemblies as it can take a long time and if it does import then its such a heavy mesh it can drag my system down to a standstill making it almost impossible to do anything with but for smaller assemblies it is lightyears better than okino.

~dave

[alexyork]

Don't forget max's X-view mode where you can turn on Faces and it will show flipped ones as bright green. Doesn't always work and can slow down the viewport a lot but it helps.

Flipped faces are the bane of my working life at the moment - so many crappy Sketchup models coming in to the studio that we need to work with...

[s0real]

how does vray for sketchup deal with the crappy sketchup geometry?

[Dariusz Makowski (Dadal)]

You can also use 2side MTL and stick the same amterial in both slots. That should produce the same look on both sides regardless of face facing.

[Da_elf]

i forget. is "reflect on back" turned on by default? that might mes things up if not

[samuel_bubat]

You should always make sure your faces have the correct orientation. Many of the workarounds do work in certain situation but usually fail when it comes to refraction.
Unfortunately it has become harder in recent max versions to spot flipped faces, but it ´s still possible. ! XView is broken, it will show faces of mirrored objects as flipped
while they are actually correct so be carefull when using it. In case of an imported Body object you can switch your viewport
to "consistant color" and it will display flipped faces as darker. In case of an editable poly or mesh I suggest you switch to "shaded" apply a standard material with 100% self illumination.
Now when you select all faces on subobject level it will show all flipped faces darker. It will show faces as darker without selfillumination, but they are harder to spot as shading from scene
lights may interfere.