3D Noob alert! UV Texturing and Normal mapping

neovirtu

Hi guys, I'm new here~ I think you'll see me around here more often, I've tried searching for a thread to help me with my question - but I can't find any, so...

I'm pretty new to the world of 3D - at university we are using Maya.

So I just don't understand normal mapping - I know what it does, and I do know what it is...but how do you texutre one?

I know you're not supposed to paint and texture a normal map - but for example, I've created a low poly plane for a floor and the normal mapping did work, I've exported the normal map into CrazyBump and made some other maps, but my question is how do I texture / UV map this? I'm doing a block floor/brick example - how will I know where the bricks are in the low poly uv? If this makes sense...

Sorry, I'm finding difficulty on what to write....

For example, if I had a low poly box and I wanted to make it look like it had cracks and more depth to it, I'd create a high poly version of the box and create a normal map from it...but how do I paint/texture that in photoshop to make sure it is correct? Would I UV map the high poly box or the low poly... I presume with normal mapping you have already know what texture / paint you're going to apply?

Sorry if I'm not making sense .....

I'm currently making a floor and I've made the normal map on the low poly and it works great I've taken it in Crazy bump and made other maps...but how the hell do I texture it!?

Gah!

Thanks guys.

Just an example of what I'm working with - how would I texture this in photoshop:

pumbaa

I'll try to give you an answer:
As far as I know there are three typical workflows when it comes to normal mapping

1: You create a color texture in photoshop, make a greyscale heightmap of it (white up, black down) and use that to create a normal map, either using NVIDIAs or xNormals Photoshop plugin or you can use crazybump.

2: You create a highpoly and a lowpoly mesh, bake the normal information from highpoly to the lowpoly model.

3: (For brick walls and similar) You create highpoly models and bake their normals to a single plane.

All of these techniques can be combined eg: you can bake a normal map from HP to LP, open it in photoshop, paint in cracks and whatnot on a new layer, keep it greyscale and then combine the two using photoshops blending mode overlay. Dont forget to merge the layers and normalize it when your done (not sure what this does but Ive been told to do it).

When it comes to highpoly stuff, you need to unwrap the lowpoly model and make sure no uv's are overlapping. There are different ways to extract the normal info from the HP to the LP, but Maya's Transfer Maps or xNormal are two pretty common ways to create a normal map. I think there's a good tut on Maya's transfer maps somewhere on the net, try google it.
xNormal is better imo, and quicker. It's free, easy and has great tutorials at http://www.xnormal.net/1.aspx

You dont have to create a highpoly model for things such as cracks, they can easily be drawn in photoshop and generated to a normal map as I mentioned in technique 1 above.

Good luck!

Eric Chadwick

neovirtu wrote: »

I know you're not supposed to paint and texture a normal map

Wrong. You can indeed paint, smear, overlay, etc. normal maps in a painting program, like GiMP or Photoshop.
Some info here.
http://wiki.polycount.net/Normal_Map#Painting

neovirtu wrote: »

how do I texture / UV map this? I'm doing a block floor/brick example - how will I know where the bricks are in the low poly uv?

If you start the normal map by converting a photo of bricks, then that photo is your guide. If you start the normal map by modeling the bricks in 3D, then you can use one of the RGB channels of the normal map as your painting guide. Often artists will also create an ambient occlusion (AO) pass from the model as well as the normal map, in which case the AO can be used as your painting guide.

neovirtu wrote: »

if I had a low poly box and I wanted to make it look like it had cracks and more depth to it, I'd create a high poly version of the box and create a normal map from it...but how do I paint/texture that in photoshop to make sure it is correct? Would I UV map the high poly box or the low poly... I presume with normal mapping you have already know what texture / paint you're going to apply?

Typically an artist will UV only the low-poly box. To figure out in the painting program where each face in the texture is going to end up in 3D... this simply requires some back and forth between the 2D painting and seeing the texture on the mesh. Sometimes the AO pass is enough of a guide though.

Sometimes an artist will UV and texture the high-poly mesh in a 3D sculpting/painting tool (ZBrush, Mudbox, 3DCoat, etc.) and bake both a normal map and a color map from it.

Eric Chadwick

pumbaa wrote: »

Dont forget to merge the layers and normalize it when your done (not sure what this does but Ive been told to do it).

Here's an explanation why.
http://wiki.polycount.net/Normal_Map#RN

PredatorGSR

To answer the question about how to paint a texture while using the normal map as a guide, there are a couple ways. Probably the best is a 2 part process, you bake AO for the model, and have it as a layer in photoshop to get the placement of everything, and then use xNormal to create a cavity map (EMB) from your normal map which acts like an AO map for all of your small details. You can also desaturate your normal map and have it as a 50% layer to guide you in painting details too.

neovirtu

Thank you so much for your help,

I feel really retarded now..

Why didn't I think of taking the normal map and using it as a guide when painting?

Gah!

A friend showed me yesterday - taking a picture of a crate box (texture) then creating the normal map and others in Crazybump and putting it on a low poly box, so I found that out yesterday too.


I've got a grasp of what Normal mapping is and I've learned from yesterday that there are different ways of applying them, and from the advice about too...

So, just to say... if had a really high poly brick with its chips and cracks, and wanted to normal it on a low-poly brick - I should UV map the low poly but use the AO as a reference to where to paint the actual cracks etc?

Why does this sound too simple... something's up!

Just kidding~