[solved] Weird rendering issue

[Rimas]

Hi!

I really need help figuring this one out.

Basically I have a volume job of 350 renders for a company that specializes in metal framing for cable management.

Now, the issue is that for some reason I get weird lines and dark spots on my renders sometimes. Not sure why exactly. And I don't remember whether this was an issue in 1.7 (currently using Corona 2).

I tried checking for the obvious things, like flipped normals, double geometry, etc - couldn't really find a fault.

The scene file (textures and model included) can be found HERE.

The reason I mentioned I have 350 of these to do is because I don't want a "just fix it in photoshop" as a solution, because it would be impractical for such a volume.

In the mean time, I'll see if I have an install of Corona 1.7 to test with as I'm pretty sure I've not seen these error before.

[Rimas]

Just swapped to Corona 1.7.4 and it also produces garbage (although ever so slightly less and also feels like it renders faster!)

[Rimas]

I applied a bland metal material with .7 gloss and there are no artefacts. Must be something in my material then :/
But I'm not sure what!

[Rimas]

Ok, this is something to do with incorrect rendering of anisotropy. If I use the exact same material without any anisotropy - it has no dark spots and stripes. If I DO use anisotropy, but disable my aniso rotation map - the problem still persists (just seems to be inverted). Can someone explain to me what might be going on here? Kinda need aniso to work here...

[Nejc Kilar]

Hmm, I havent' downloaded the files but... Are these CAD models you are working with?

[Rimas]

K, so this isn't an issue just with my material, the same happens with Corona material library materials too...

Seems like Juraj ran into a similar issue with anisotropy, but that one presented itself in the form of a terminator...

[Rimas]

@Nkilar - yes, CAD models.

[dj_buckley]

That geometry is a mess.

I've just remodelled the piece nearest the camera and applied your material and approximately matched the mapping and it works fine.

CAD Geometry like this is always horrendous, you might be better asking for the native files, you might find they're proper nurbs based models from Rhino or Inventor or something similar, in which case they should be able to send stp or iges files which would better maintain the smoothing and geometry curves

[Rimas]

Thanks for the reply. Once nkilar mentioned CAD I started investigating. Basically what I need to do on import is reset the xform and everything renders fault-free :D
Though I had to adjust my material to match the agreed-upon "flake" size of the galvanized steel. So I'm setting up a new master blank max file prepared for import now... Ah well!

[Rimas]

CAD Geometry like this is always horrendous, you might be better asking for the native files, you might find they're proper nurbs based models from Rhino or Inventor or something similar, in which case they should be able to send stp or iges files which would better maintain the smoothing and geometry curves

That being said, I don't know if you noticed that I included an IGS file next to the MAX file - these are curve body files (I have no clue made in what, though). That's what we got sent, 350 of those.

Well, resetting the xforms still beats remodelling anything or pesterring the client for anything other than what they have, since they have no clue how any of this works to begin with (and we're dealing with the middle-men too...)

[Frood]

Why remodel? Why not use the iges files as body objects, they seem to render fine (top one is body object, bottom: your original objects)


Good Luck

[Rimas]

Why remodel? Why not use the iges files as body objects, they seem to render fine (top one is body object, bottom: your original objects)

Good Luck

I did try to use them as body objects and it didn't work for me. How did you import, specifically?

Thanks!

[Frood]

Hmm, nothing special, see attachment. Strange that it did not work.


Good Luck

[Rimas]

Hmm, nothing special, see attachment. Strange that it did not work.

Good Luck

The magic was in the flattened hierarchy :)

Though I have another issue now - the parts don't have enough subdivision resolution and are all low-poly, the curves look nasty. So far the solution seems to be to pick the part, go into the body properties, check "use viewport mesh" in rendering approximation tab and...do that for all the other parts...at which point it's still faster to import as mesh and reset the xform on the whole thing. :/

[Frood]

Well, whatever works for you. But render/curve quality should be good when using "Production" in "Rendering Approximation" (it defaults to that here, dunno if this is a global or local setting).


Good Luck