Photoshop  CS4 Extended - Painting on a 3D Model
© 2009 Robin Wood
This tutorial will show you how to paint on a model in Photoshop CS4 Extended.
I’m assuming that you already know how to open the model, light it, and move it around. If you don’t, please watch those videos to learn how. You'll find them on this site.
If you know all of that, then it’s finally time to start painting!
If you open the 3D Panel, as we have before, and go to the Material tab, you can see any Materials that happen to be associated with your model.
In this case, there are three, because there are three materials in the Second Life® Avatar. You can see them listed here. Material_Lowerbody, Material_Upperbody, and Material_Head.
If you look in the Layers panel, you can also see the Textures that are currently being used on the model.
Don’t confuse these two things, even if they have similar names.
You can add different textures (we’ll do so in a moment,) but you can not add Materials. That has to be done in your 3D program.
We’ll come back to the Material pane of the 3D panel in a bit. For now, I’m going to close it, so we can concentrate on the Layers Panel.
Here in the Layers panel, we can see all the textures associated with this particular 3D layer.
You can hide them, or show them, using this flippy triangle.
When they are shown, you’ll find that they are listed by Mode.
In this case, all the textures are Diffuse color. You can see the mode here, at the top.
So, we can just grab the Paintbrush tool, and start to paint!
When you have a 3D layer selected, any strokes that you paint will wind up on the model.
But look at this! I got an error message. It’s saying it can’t edit the texture! What’s going on?
Let’s click the Change Texture Target button, and see.
Ah, see there? The selected layer was hidden.
Whenever you get a message like that, you need to open the texture and take a look.
Let’s unhide this layer.
(By the way, you won’t get that if you just start to paint on the Avatar. Instead, you’ll be painting on the Background layer. I set that up, so I could show you the error.)
While we're here, let's close the Background layer.
Now we can save this texture, and close the window here.
Let’s make sure we know what we’re going to be painting on for these other two.
To do that, just double click on the Texture name, here in the Layer panel.
That will open the .psb file that's associated with that texture.  (I think of it as Photoshop Big.)
You’ll see, when you have it open, that it behaves in all ways just exactly like a normal layered Photoshop document.
So, you can resize it if you want, just the way you normally would. If you want to resize the texture to 1024x1024 while you’re working on it, for instance, you would just do that here. 
You can click on the New Layer icon, as you usually do, to make a new layer to paint on.
You can hide a layer, by clicking the eyeball icon, just like you always do.
Save the file, and the changes will update on the model.
Repeat as needed, with other materials. In this case, we’ll have to open all 3 materials and make a New Layer if we want to paint a seamless texture across the different material zones without touching the texture that’s already there.
We’ve done two of them now, so let’s do the head, and then we’ll have all 3.
New Layer, hide Background, and Save.
Once you have the layer to paint on, just choose your brush, and start to paint!
Let’s zoom in a bit, and do that.
If your computer is powerful enough, you’ll be able to watch the paint appear on the map. 
If you don’t see it there, it’s become disassociated from the image, like this one has. 
Just close it. You won’t lose anything. Photoshop is busy painting on the map that’s still actually associated with it. 
I’ll open it up, so you can see that.
And there it is.
And really, that’s all there is to it.
You can use filters, clone stamps, shapes; anything you want.
As long as you have that 3D layer selected, anything you do will show up on the model.
To paint on a different layer in a texture, Open it, and select the layer you want. Then Save and Close.
(Or just leave it open and paint, if your computer will do that.)
As you work, you’ll find that you can only paint on the side of the model that’s facing you.
This is a Good Thing, because it keeps you from making brush strokes that you can’t see or control.
All of that is controlled by the Paint Falloff Angle, which I’ll cover in a video about advanced painting.
For right now, just be aware that this is normal, and what it's supposed to do. 
If you want to cover an entire area with a color or pattern, you can either turn the model a lot, or open the Texture.
Select an area.
And fill it right on the Texture.
Add a new layer for touchup,
And then use the brushes and things to touch up the seam, here on the model.
There is nothing that says that you can’t work on both the flat texture, and the model!
I'm going to use the lasso, and select all of these dots, and make them go away. Just hit the Delete key, drop the Selection [⌘ D on a Mac, ctrl D on a PC], change the layer that I'm working on, there we go. Get the Elliptical Marquee tool, make a few more dots! Just make 'em, and fill them. Repeat as needed, to fake the side here, so that it looks like it's one seamless texture that goes the whole way around.
Now, as you work, you might find that sometimes it’s hard to get in to the areas you want to paint on.
If that happens, you can enable Cross Section easily get to those bits.
Just go to the Scene tab of the 3D Panel, and enable it, at the bottom. Just like that.
By default, it’ll have a Plane visible, but if you don’t like it, you can turn it off, like so.
Or you can change the color and visibility, here, of course.
If you’d rather just see a thin line, to show you where the model edge is, you can enable Intersection, here.
Click the Flip button, here, to see the other half.
Or you can also change the offset, or tilt, or the axis of the cross section, with these fields at the bottom.
We can change the offset to -15, for instance, to get to that side without her arm being in the way.
You can play with those on your own.
Of course, it’s possible that you already have a texture and all you want to do is tweak it here on the model.
That’s easy, too!
Just go to the 3D panel, to the Material pane, and click on the Edit Texture icon next to the kind of texture you want to load. In this case, it would be Diffuse.
Choose Load Texture from the menu, browse to the texture you want to use, and Open it!
If you have another texture that you have to open too, then go ahead and do that one as well.
In this case, I have to do the Material_Top, on the _Upperbody, in order to make sure that I have them both. And there we go, there it is!
It’ll show up, with all its layers and masks intact.
The name of the new texture will even replace the name of the texture that is showing. It's really easy!
In this case, because I’m lazy, I’m using Another Skin by Eloh Eliot, with Vint Falken’s New Bikini on it. And you can see the name, here.
If you want to add a different kind of texture mode, you do that here too.
I’ll put a bit of a bump on her suit, so you can see how that works.
Just click on the Edit Texture icon of the texture mode you want to make. We need Bump Strength for a bump map, and either Load a texture, or start a New one from the flippy.
I don’t have one ready, so I’ll make a new one.
Now that we have a new texture, we have to tell Photoshop that we want to paint on it, and not a texture that uses another mode.
In the 3D panel, on the Scene tab, choose Paint On.. Bump, or you can go to the 3D menu, and choose Paint Mode > Bump, here.
Now, because bump is determined by light and dark, I’m going to open the new texture, and make it black to start with. That will be the lowest elevation on the bump, with white being the highest, of course.
Double Click, Invert, Save, and Close.
Then just paint with white, and you have a bump!
Of course, if you’re doing this for Second Life, you can’t use bump maps there, and you can’t burn shading onto a texture here in Photoshop. But if you have an application that will let you burn shading, this is how to get a bump to burn.
Now let’s change back to painting on the Diffuse, so I can show you something else.
3D > Paint Mode > Diffuse.
If you want to paste an image onto the model, it will, of course, wind up on a different layer when you paste. But you can merge that with the other layers, and make it part of the texture. Let’s see how that will work.
First, I’m going to paste in an image that I’ve had waiting on my clipboard. This is going to be a tattoo!
Next, let’s make sure that we have new layers in the textures, for the tattoo to land on. It’s going to be on both the Upper Body and Lower body materials, so I need to put an empty layer into both maps.
Double click to open, Make a new Layer, and give it a name.
 I’ll call it “tattoo.” It’s always a good idea to name the layers.
Save, close, and repeat with the other one.
Open, New Layer, Name, Save, Close.
Now use the Move tools, to get the model into position, so the tattoo is exactly where you want it. I’m going to use a preset, up here in the Tool Options bar, so that we’ll be looking directly at her back. You can always use these, and you can save your own, too, if you want. (The camera has them too, if you prefer to move the camera, not the model.)
Now I'm just going to resize the tattoo, and move it into position on its layer.
Finally, when it’s perfect, hold down Command (ctrl on a PC) and tap the E key, or go to Merge Down, in the pop-out menu on the right corner of the Layers palette.
Your artwork will fall down onto the image maps that you have selected in the materials. Just like that!
Let me move her around, so you can see.
Now let's look at it, on the bottom map. There it is. And on the top map, and there it is again.
Finally, you may want to get your perfect textures back out of the 3D layer, and save them as normal .psd files, or convert them to something else, so you can use them in other applications.
It’s as easy as anything to do that!
Just double click the texture to open it, and Save As… (Hold down the Shift key, and hit Command S, or ctrl S on a PC, to save the file.)
Browse to wherever you want it, pick a format, and you’re good to go!
I’m saving them as .psd files, so I’ll have all the layers and the flexibility that goes with them.
And that’s it!
Because this is Photoshop, there’s more you can do, of course. There's always more you can do! But this should get you started painting on a model in Photoshop CS4 Extended.
I’m Robin Wood, and I hope you found this helpful.