A huge amount of attention has been given to ZBrush 2's multiresolution sculpting and difference mapping capabilities, which is great! But don't forget that Projection Master is a phenomenally powerful tool for high quality texturing. In fact, if you've been impressed by the projection painting demo movie for a certain other 3D texturing application, you'll be blown away by ZBrush's versatility in this area!
This tutorial is going to demostrate several methods by which imported texture information can be sampled and used to create another texture in ZBrush. We'll start out by using an imported photo and applying it to your texture. After that, we'll get into some more unusual techniques such as creating a tattoo. Enjoy!
Part 1 - Texture Cloning
OK, here's the scenario. You have an image that would make a really good texture, but it's not seamless. Maybe you licensed it from online, or maybe you just took a camera with you and found something that would work. Either way, the question remains: How do you get the photo onto your object so that it looks good?
For this example, I'm going to use an image of some patterned stone. What we want to do in this case is use the imported texture to build a larger one. Here's how:
Create a base texture (in this case, I'm using white, 2048x2048) and then click the Projection Master button. Using the default settings, drop the model to the canvas.
Now select the Plane3D object, then import the texture. We just want to paint color; no depth or material, so set the Draw palette to Rgb and turn Zadd off.
If we were to paint a brush stroke now, what we'd get is a rectangle of color. This isn't too good for creating a smooth texture, so there are two more things that we need to do.
First, select an alpha with a nice radial falloff. Brush 49 is a good choice. Next, set Draw>Rgb Intensity to 99. Any value other than 100 instructs ZBrush to use the alpha to control transparency.
Now when you draw your brush stroke, the texture is painted with a radial fade that matches the alpha.
Use the gyro to move it into position, then snapshot it in place. By snapshotting multiple copies, you can build a non-repeating texture. In fact, you can even rotate and scale the instance however you'd like to add further variety to your work.
You can also use this technique if you have an image with an alpha channel. Import the color into the Texture palette and the alpha channel into the Alpha palette. The texture can then be painted using the alpha for control.
Part 2 - Transparent Texture
In this case, we're going to use ZBrush to apply a rose tattoo to a model. I already have an image that will work, with a transparent background. Opening the image in Photoshop, I add another layer below it that is 100% black (the color that ZBrush uses for transparency). Now the image is saved as a PSD and imported into ZBrush.
In the Texture palette, activate the Transparent switch.
Apply the texture to a plane and use Projection Master to paint it onto your model. Since a plane is being used, you can rotate the image however you'd like while you work.
The thing to remember about texture transparency is that it's all-or-nothing. Only a color value of 0,0,0 will be transparent. A value of 0,0,1 would appear as black.
Part 3 - Stencil
A third technique for projection painting will work with any grayscale image. In this example, we'll use a tribal design to paint a tattoo on the model.
Any grayscale image will work with this technique. Black will be the "paper" of the stencil, while white will be cut out. Shades of gray may also be used, and will result in partial transparency. This is a marked difference from the transparent texture approach.
Once the model has been dropped to the canvas, import your alpha image. The tribal design that I'm using was created as a black pattern on a white background, so we'll use the Alpha>Invers button to reverse it.
(Note: If you forget to do this, you can also use Stencil>Invr to reverse the stencil while it's active.)
Now press Alpha>Make St to convert it to a stencil.
The stencil appears as the reverse of your alpha -- white paper with black holes in it. You can change this appearance using the Stencil palette. For example, the Elv button will show it as an outline. This is completely optional, and has no effect on the results.
What you SHOULD do is activate the Wrap Mode. This causes the stencil to conform to the surface beneath it.
Now you can hold down the space bar to activate the stencil's Coin Controller. Clicking and dragging on the various parts of it will let you move, scale, and rotate the stencil in a variety of ways. Use the coin controller to position the stencil where you want your tattoo to be.
Now all you need to do is select your brush, etc., and paint through the stencil. I usually prefer to use the Simple Brush with Alpha 00 and the Drag Rectangle stroke. This makes it easy to paint uniform color through the stencil with a single stroke.
Once you have used the stencil to paint what you want, be sure to turn it off by turning off the Stencil>Stencil On switch. It MUST be turned off before you pick the model up from the canvas again.
The stencil method is really very powerful, since it provides a guide through whch you can paint anything you'd like. Here are a few examples of what can be done:
In fact, you can even use it with a high resolution mesh to paint displacements!
Hopefully this short tutorial has turned you on to some techniques that you can use in your own work. The nice thing about having three distinctly different techniques available to you is that no matter what your needs may be, ZBrush 2 offers a way to accomodate them.
Experiment and have fun with these methods. Please feel free to post your results in this thread!