model gets strange black/grey "shaded" polys and it just looks weird? why?

[Anonymous]

Hello everybody! My first post! I have a problem that have happened to me now many times and I don´t know why. Right now I use 3dsmax 2013 x64 (Nitrous) but the same thing has happened in 2012.

As you can see in the picture I get weird "shades" here and there. If I move around the model it changes which polygon that get that effect. I think it is related to when I fix open edges or remove a part (it have happened when I just removed a couple of polys). Often I also have had UV´s applied (if that could be related to the issue).

Maybe some of you hopefully recognise the problem when you see the picture I attached, because it is difficult to explain why it emerge and when. Sometimes it just seem to pop up from nowhere. Maybe it is bug-related? But if it were, then both 2013 and 2012 had/have the same problems...

[Bill_Sands]

From looking at the 1 screenshot, it looks like you might be seeing different shading on the different smoothing groups. As you rotate the model in the viewport you would see the default lighting in the viewport change the shading on the different faces. This would oly occur if there were strange smoothing groups I think.

To better resolve the problem it would help to have the file to look at. 

I would recomend that you have a look also at the "Viewport configuration" settings, under the "Visual Style & Appearance" tab. Changing the settings in there should have an impact on the way you view the model, but it won't change the geometry if it is the geometry at fault.

There could of course just be a multi sub object materail on the object, and some strange poly ids.

There are quite a few options, so the model would probably help more. (you'll need to zip it up to attach it)

Bill

[Anonymous]

Check the model for: Flipped faces, Unwelded vertices and Smoothing Groups. You could run AutoSmooth on it, or set smoothing to one group.

[Anonymous]

Thanks for the help! I have tried changing the smoothing groups to 1, and auto smooth it and it did not change the problem. I haven´t changed anything in the viewport configuration, they are at their default settings. The poly ids should be ok...I hope. I´m using multimaterial, but i´ve had this problem before even when I not were using multimaterial.

I attached my file. Sorry for the weird filename 😉

[Anonymous]

Thanks! The weirdness happened when I welded the vertices (I think). But why should that be a problem? I don´t understand.

[Bill_Sands · Accepted solution]

So, it took a few minutes, but I have an answer for you.

The problem is with the geometry normals. Every vertex, actually every corner of a triange (because a vertex can have more than one normal), has a normal, which describes which direction the "normal" side of the poly should face. These have become very messed up on your model.

Here's what to do to take a look:

select the geometry and add an "edit normals" modifier. I think by default the normals will be huge, so change the "Display length" to something more managable. What you'll see is that every vertex has a load of lines coming out from it. These are the normals. With the "edit normals" modifier selected (highlighted in yellow in the stack) press ctrl+A to select all the normals. Then hit "unify".

You shuold now see that the body ahs become smooth and the anomaly has gone.

I hope that is explained well enough.

Oh and by the way, you can then collapse the "edit normals" modifier in the stack.

Cheers,

Bill

[Anonymous · Accepted solution]

Sorry, I was occupied before so I could not answer. I tried your solution and it worked somewhat. But sadly a new problem followed with another kind of shades. So I played around with the different settings until I found out that "Break" worked better than "Unify". Now it looks a lot cleaner (and hopefully it will stay that way). Thank you for helping out and pointing me in the right direction. Even if I consider myself quite home in 3ds max there is always stuff to learn 😉

Thanks again,
Mathias

[R.Welsing · Accepted solution]

i had the same problem and it worked for me. however i u sed reset normals instead of break or unify sins i wont be able to use a smoother after with break and unify and with reset i can. 

[Anonymous]

WOW That reset normal business fixed my issue. many thanks

[Anonymous]

awesome! this solves the problem immediately ! Thank you !

[mischesn]

Sorry for kind of a necro-ing this rather old thread, but this post should probably be made sticky.

Why?

Because this solution with Edit Normals->Select All->Unify->Break effectively solves the eternal problem when modifying geometry of about every object imported from Sketchup(from any version, using the new as well as the "legacy"(and still vastly superior) importer, imported into any Max version).

As soon as you delete a face or modify the vertex order in any other way, normals and therefore shading will almost certainly get broken right away and no amount of Edit Poly operations like Flip, Clear Smoothing groups, etc. can do anything about it(it usually makes things even worse).

I just can't count how many times using Edit Normals and collapsing it back to Edit Poly literalilly saved my ass.

[adminSWF2T]

Max 2022 has this issue when i use nurb. Looks totally fine in Max 2017, or when in 2022 using turbo smooth.

It's not the normals or geometry, just makes weird pattern. 
No Nurbs or Turbo smoothnurbs aplliedturbo smooth applied
This is driving me crazy cause I would like to just turn it on or off to check edge loops.

[rilana.welsing]

Hi there, Luckily i got an email notification about your post.

I am not sure why it is happening but i do think it has to do with the normal's and here is how to fix it.

Go to modifiers and find edit normal's.

Then select everything (lines will appear that you can select).

Then in the modifier menu select reset normal. and then change it back into a poli or mesh.

Hope this helps!.

[adminSWF2T]

Ok I like to keep the nurbs on/off.

If I turn off nurbs and do the edit normals (which was done) and turn nurbs on same thing.
If I leave nurbs on and edit normals and collapse the stack, I just sealed in the nurbs as the geometry now.

As mentioned turbo smooth which is like nurbs has no problem and turning on nurbs in 2017 displays fine. this has been like this since upgrading to 2022.

[kenshin_rock1]

hi ..i am facing the same issue...after applying nurms its becoming black and white ...same issue as you..i hope you found the solution ...

[maazrehan8181]

Worked exactly. Thanks