Mechanical Object Normal Mapping problems

Showster

Hi all,

I've had a flick through the normal mapping thread but couldn't find what I was looking for.
I'm in the process of trying to normal map some hard surface objects and kepp getting plenty of errors.

Are there any particular differences I should watch out for compared to organic objects. It would be great if anyone could show an example of a vehicle / mech they've made.

This is the thing I'm mapping



Severe case of smoothing nasties

Sam Hatami

First thing that came to my mind is that looks like its inverted.

But it might just be the poly flow of the low poly

Care to share that part of the local? and perhaps even the shaded low poly?

Eric Chadwick

What software are you baking in, and what material/rendering setup exactly are you using to view the results?

Several things in here that should help you.
http://wiki.polycount.net/Normal_Map

Showster

@Metal mind, I've put a screen grab of the low poly on the render. If you wanna check out the file pm / msn me.

@Eric, cheers for the link I'll have a read through must be missing something daft

I'm using max 2009, with render to texture.


The material just uses normal bump with dx display selected. Hopefully theres enough to go on with the use of this screengrab.



In this particular attempt I've removed all the smoothing groups from the low poly.

Eric Chadwick

DX Display doesn't render normalmaps correctly in the viewport.
http://wiki.polycount.net/Normal_Map#ShadersAndSeams

Showster

cheers Eric much appreciated :-) fingers crossed I can sort it out now

Eric Chadwick

Also check out the links at the bottom of this section.
http://wiki.polycount.net/Normal_Map#SmoothingGroupsAndHardEdges

And see if you can use object-space normal maps instead of tangent-space. This would save you a ton of headaches, don't have to deal with smoothing at all.

Ghostscape

EricChadwick wrote: »

Also check out the links at the bottom of this section.
http://wiki.polycount.net/Normal_Map#SmoothingGroupsAndHardEdges

And see if you can use object-space normal maps instead of tangent-space. This would save you a ton of headaches, don't have to deal with smoothing at all.

Maybe it's just me, but I really can't see many instances outside of cinematic objects and a handful of hero objects (mostly FPS guns) where object-space normal maps are worth the incredible loss of texture density that you get with tangent space and being able to mirror and re-use textures. Are there ways around the unique unwrap restriction? Unicron entirely symmetrical and outside of keeping parts of his front/back unique to make him appear asymmetrical, it seems incredibly wasteful to give him a 100% unique unwrap.

Eric Chadwick

Object space maps can be mirrored, if the shader is written to support this.
http://wiki.polycount.net/Normal_Map#TangentSpaceVsObjectSpace

Ghostscape

EricChadwick wrote: »

Object space maps can be mirrored, if the shader is written to support this.
http://wiki.polycount.net/Normal_Map#TangentSpaceVsObjectSpace

Oh hey, that's awesome. Does that allow for you to mirror, say, Unicron's left calf's left side over the right, and use that same texture for his right calf's left and right sides, or does it need a single (albeit arbitrary) mirror plane?

Eric Chadwick

Read CrazyButcher's notes here.
http://boards.polycount.net/showthread.php?t=53986

Showster

I'm shooting to get him into unreal 3, I've only seen them use tanget space in the editor. Does anyone know if that engine can support world space?

Sage

The only way I have found to get rid of what you seem to have with tangent space normal maps is to make sure that the low poly lights well. What that means is that if you don't see smooth shading on your model inside Max that crap will bake into your normal map. Try and get the most uniform distribution of edges on your low, you need to add a ton of edge loops so they are grind like. It's best to make a copy for just baking. I do this with connect with the options open so you can dial it up pr down. Usually just having it prep for subd smoothing does the trick though. Sometimes you need to add more edges. Once your low had enough edges all kind of problems go away, like issues with seams. This isn't the best way but the only I have found on my own to deal with the problem. Another thing to try is to inset your a set of faces. This makes a set of faces look flat (hard)even if you have ones smoothing group applied to everything the entire model. Helps at times when everything else fails but not great. In Unicron's case it might work but just adding extra loops at the edges like if this were a subd model and in the middle should do the job.

Example of where I did what I explained, not saying it's great though.

http://apsentertainment.com/previews/ent_n08.jpg

http://apsentertainment.com/previews/entsheet01.jpg

Alex