Help! Normal Map Suddenly appearing weird

charlesgams

Hello my names charles I've decided to write this on a forum because this problem that I have I've never encountered before since  making normal maps and rendering them in 3ds max for 4 years lol.  

Headsup : I normally create my normal maps in zbrush and export it correctly for 3ds max which is to flip G in the normal creation panel and flip it vertically just in case someone suggests if i have :-) .  I also tried creating normal maps in xNormal , again understanding that the swizzle coordinates need to be : X+ , Y- , Z+ and if that wasnt enough i even tried Y+ but still problem persits.

Problem: My normal map renders out fine in 3ds Max , however I noticed that when I rotated the 3d model which had the normal map . The normal map indented my detail so essentially the normal map becomes inverted when rotated at certain angles although I've only tested a 180 angle .  I've check the normals of my mesh  using  the normal modifier , however I noticed that when i use reset xform  on the model , the model renders the normal map correctly but goes back to square one when i rotate the model again. I'm aware of the different types of normal maps that exist such as world space , object space and how these two types are used for static objects. I use tangent space normal maps which is essentially the best type .  This problem has never happened to me up until now . 

Furthernote:  On a positive my normal map renders out correctly in the Unity Game Engine . It  makes me wonder is my 3d model completely broken LOL

Sorry for long post but its delaying my progress and would like to see if anyone can help me :-( 

I've posted rendered images to better illustrate my point . I'm using 3ds Max 2014 , however the same issue happens  in 3ds Max 2015  and as I stated at the start of the post I've never encountered this from for like 4 years of using 3ds max meaning all the previous versions i had no problem with normal maps. My suspicion is that it could be mesh related but as i stated the normal map renders fine in Unity .

I'm using mental ray to render this model using the arch and design material setup

Eric Chadwick

Moving this from General Discussion to Technical Talk where topics like this get more appropriate eyeballs.

charlesgams

oh right cheers thank you didnt see the technical talk 

Eric Chadwick

Usually when posting a problem like this, people include screenshots of the error. How you describe something could actually be something entirely different, based on how it looks. Show a screenshot of when it's wrong.

Also, indicate exactly how you are viewing the normal mapped model. What is the material setup, is it viewport or render, which software including version number, etc.

charlesgams

cheers just updated my post thanks alot will take note of this in the future

Eric Chadwick

OK. You should not expect mental ray to render normal maps the same as Unity. It only matters how the normal map looks in the target game engine. How does it look in Unity?

Zbrush baking is not synched to Unity. To get normal maps to shade correctly in Unity, bake the map in Xnormal with this plugin. 
http://farfarer.com/blog/2012/06/12/unity3d-tangent-basis-plugin-xnormal/

It looks like you're mirroring the UVs. This also requires a certain workflow.
http://wiki.polycount.com/wiki/Normal_Map_Modeling#Mirroring

charlesgams

I've check those links before it doesnt relate to my issue. I understand that 3ds max handles normal maps different than Unity and zbrush not being synched to Unity. The main problem is that it looks off in 3ds max as stated and shown.  I've had no problem at all before when working on other models its only this one that when i rotate with it to in future create a turntable that the normal map behaves incorrectly in 3ds max

Eric Chadwick

Why are you rendering a turntable in 3ds Max? This is a game model, it should be rendered in a game engine.

charlesgams

I'm rendering a turntable or plan to for a future showreel that I'm going to do . I'm pretty sure you can render this model in 3ds max regardless along with a normal map on an offline engine such as 3ds max. I've been rendering this way for a while and its worked fined until now 

Eric Chadwick

First, showreel is the wrong way to present your work. Employers prefer to see screenshots, from a game engine. A browser-based 3d viewer like Marmoset or Sketchfab, is great too.

We only want video if you're showing animation, effects, gameplay, walkthrough of a game level, etc., things that absolutely require motion. Turnarounds of static models are a big waste of time.

Second, offline renderers should definitely not be used for game models. Unless you are making game cinematics, in which case you would use non-game high-res models anyhow.

Thirdly, you did not have notice the errors before, but they were there. Normal maps must be synched to render properly. If you are not baking with this in mind, it is extremely rare for it to just "work."

These links might help you
http://wiki.polycount.com/wiki/Portfolio

charlesgams

I understand your points but I intend to not just have a static turntable my plan was to rig and animate the characters thats what I've always been doing for awhile and I've checked my other models and normal maps are completely fine and render properly in 3ds max . Its just for whatever reason this particular model it seems to not work as i expected i even repeated how i normally render normal maps on another model in 3ds max and it worked completely fine , unless normal maps are only meant to be used for game models strictly if thats the point you mean 

Eric Chadwick

OK, it is your call what to do. Just know that turntables are really annoying for employers.

I looked at your Artstation page, and I see the shading errors there too. Your lighting is very frontal which tends to hide errors. This might be the same model, but here for example the left side (character's right arm) shows mirror-shading errors. The vein on the bicep is inverted, etc.

charlesgams

Yeah I see that was a render in zbrush.I'm not dismissing your points about the turntable I intend to make just character shots of my models regardless my main issue was the invert problem but i guess we got sidetracked lol but it helped me acknowledge some things.  Also like I said earlier about this model being the first time that i encountered such a problem  all my other models i had no shading/lighting problems as you could see on my artstation . So now i guess  what should i be looking at regarding your point cause my model is obviously affected somehow but whats the solution 

Eric Chadwick

The solution is not to render them. If you're animating, get that into Unity and capture from there. Or better yet, import the anim into a web 3d viewer.