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Painting Normal Maps in Zbrush 2

The goal of this tutorial is to demonstrate the ease of "painting" a normal map directly in Zbrush 2. While Zbrush 2 can be used to make normal maps in other ways, this method may not be so familiar to those getting acquainted with the program. Hopefully, this tutorial will illustrate the relative ease of making normal map using Zbrush's flexible toolset.
The first thing you'll need to do is resize your document, mainly to make it powers of two (512x512, 1024x1024. 512x1024, etc.). Do this by clicking on the "Document" menu and turning "Pro" off. "Pro" is short for "Constrain Proportions" and it is on by default. Once turned off, you will be able to explicitly change the dimensions of the document. Keep in mind Zbrush 2 will keep a resoluton of 72 DPI, so if you need more detail, you might want to double the size you are working at. You can downsize the dimensions and upsample the resolution of the document later.
To confirm the document size change, click the "Resize" button. You'll get an alert dialogue warning about the undoable nature of this decision. Hit "Yes."
Now the document is resized and you can begin to get some work done. Navigation may be a little tricky at first, so it's best to go over the basics. On the right-hand side of the screen is the basic navigational tools you'll need. The most commonly used are the Scroll and Zoom buttons. To scroll, click the Scroll button or, press the Space bar and drag with your mouse. The document will move all over the Zbrush workspace. Press the Zoom button to move to enlarge the document (note, the resolution of the document might mean certain areas become a little grainy). A shortcut for zooming in is to tap the "+" key. To zoom out, tap the "-" key. The "Actual Size" button resizes the document to a 100% zoom. The "AAHalf" button zooms the document to 50% of the actual size of the document.
To paint a normal map directly, you'll need to load the NormalRGBMat material. It comes with Zbrush 2, but it isn't automatically available upon launch of the program. Look to the left side of the page and click on the Material ball. A menu will pop up and you will see an "Load" button. Click on it. Make sure you are in the Zmaterials folder (\Pixologic\ZBrush2\ZMaterials). Sometimes you have to browse a bit to find the right directory.
Pick the NormalRGBMat from the available materials.
With the NormalRGBMat loaded, go to the "Layer" menu and click the "Fill" button. The document will be flooded with an even lavender-blue normal map material.
With the document filled with the NormalRGBMat, you can start adding detail using any of Zbrush's tools. This includes the standard brush tools, geometry tools; anything available in the tool menu.
Pick a tool from the side menu and take a second to choose an alpha from the Alpha menu. The preset Alphas work pretty well or you can make and import your own. For beginners, it's probably best to just pick an appropriate alpha from the Alpha menu. The alpha acts much like a brush shape in Photoshop or Painter. However, the alpha is a lot more flexible than being just be a brush, as will be obvious towards the end of the tutorial.
Just as you selected a tool and an alpha, you'll need to find a stroke that works for you. Each stroke gives different results and there's really no easy way to explain how each stroke behaves. The best advice is to try each one out so you become familiar with each stroke's indvidual behavior.
Now it's time to start drawing. Click on the active document area or draw on it using a graphics tablet. Notice how a single click embeds the shape of the alpha into the normalized surface with an emboss-like effect. This is, effectively, a usable World- or Object-Space normal map (not a good one, mind you) but it would work in a game engine that supports Object-Space normals. The embossed area will suggest lighting and depth on a mesh, making it look more detailed than it actually is. Obviously, this wouldn't make much of a normal map, so it's time to use Zbrush's tools to greater effect.
Click the "W" key. This activates the Zbrush "gyro." When using the gyro, you can move, scale or rotate the tool you just created. The tools and buttons to do this are located at the top of the screen under the menu, or you can use the hotkeys to do the same job. The shortcut for move is "W."
After you move the tool, try scaling it. The scale button at the top will do it or you can use the hotkey for scale: "E."
Continue to adjust the tool. Scale, move, rotate. Do what ever you want. The gizmo makes for easy transformations once you spend some time learning how it functions.
Now, return to Draw mode by hitting the "Q" key. The gyro will disappear. You won't be able to move, scale or rotate the object as you could when the gyro was available. The tool is embedded back into the canvas.
To make seams and tiling easier to see and correct, Zbrush 2 offers a very simple way to offset the document. Hold down the tilde key (~) and click and drag in the document area. The document will offset as you drag. You can now see any possible tiling issues. You'll want to check for tiling seams often, so remember to continuously offset and check for seams.
If you need more precision in how the image offsets, you can use the Layer>Dispace H/Displace V sliders to incrementally offset a document. By entering precise values in the fields, you'll be able to keep track of how far something has been moved. It's not as fast as clicking the tilde key, but the tilde key method for offsetting creates problems when you have to match exact positions on your document.
Now is a good time to use alphas more creatively. Alphas can be used as a stencil, enabling you to mask areas like frisket with an airbrush. This handy tool is very usefull when you need to make sure certain parts of a texture need to look a certain way, but you don't want to influence other parts of the texture. To begin using the alpha as a stencil, select an alpha from the Alpha menu.
Go to the Alpha menu at the top of the screen (you could have done this to select the alpha in the previous step, but the Alpah menu on the side is a little clearer). Click on the "Make St" (Make Stencil) button. Now the alpha you just selected is loaded as a stencil which you can activate using the Stencil menu.
From the Stencil menu, click the "Stencil On" button. The alpha will show up on the doc, but it will look slightly transparent. This means the alpha is now an active stencil. Everything exposed in the stencil will take whatever modifications you put on it. Whatever is hidden by the stencil is unaffected. Tap the space bar to call up a special stencil manipulator. Using this little GUI, you can rotate, scale and move the stencil. It takes a little getting used to, but you'll get the hang of it with consistent usage.
Pick a Tool, Alpha and Stroke and begin "painting" in the masked area. You'll notice that the masked-off area isn't directly affected while the exposed area begins to take on shape. You can build up neat little layers of depth by painting a little, moving the stencil, painting a little, move the stencil. Also to keep the shape from becoming too patterned, rotate or scale the stencil as well as moving it. Also, mix in other alphas for a greater variety. Make sure you offset your work to check for seams.
Invert the stencil to continue making changes to the doc. Go to the Stencil menu and click the Invr button. With the stencil inverted, you can further refine your texture. Push down cracks a little bit farther, smooth out areas that would be harder to get to or add texture effects to the newly exposed area. It's really up to you to decide what you want to do.
Keep on making changes to the mesh using the Stencil, if it is helpful. Turn it off when you no longer need it. Keep in mind you can use it, along with any alpha by repeating the steps above. Select a tool and click once in the document. Click on the Snapshot button. You now have a copy of the tool selected.
Click "W" to move the tool with the gyro. Pull it somewhere on the screen. Notice how the original tool stayed in its place. Make another snapshot and move the new tool to a different part of the screen.
Click on "E" to scale the new tool. Rotate it with "R" if you feel so inclined. Press "Q" to go back to regular draw mode.
Offset the image to check for seams. Fix any you see. Add detail using the tools and brushes where you see a need.
Just to drive home that there are many ways to build a normal map in Zbrush, grab the Gear3D tool from the Tool menu, and click on the "Initialize" rollout.
Play around with the Initialize settings until you make a shape that is interesting. There are a lot of possiblities with many of the geometric primitvie tools. Once you have a shape you like, drag it out onto the active workspace. If you wanted to Move it around, press "W." If you want to rotate it, press "R". The point is, get it on the page in a way that satisfies you. Then drop it. Use the BlurBrush or Smudge tool to smooth out any rough edges. Offset this image a couple of times and check for tiling problems. If you see a problem,
When you have the document the way you like it, you'll want to take a snapshot and export the file. To do this, click the "Texture" menu and click the "GrabDoc" button. Pressing this button tells Zbrush to capture an image of the document. Once you press the button the image is instantly captured and loaded into the active texture slot.
The final step in the process is to save the image. Under the "Texture" menu, click the "Export" button. Pick a file format and a destination directory. Give your image a proper name and click the "Save" button.
Save the Zbrush document by going to "Documents>Save" and save your file as a .zbr file. Over time, you'll begin to build a library of different documents, which you will refer to over and over again. A .zbr is analogous to the .PSD file format. Usually, the .PSD format is where everything is stored (layers, paths, etc.) and the final file used by a game engine is a composite file saved in different format (.DDS, .TGA, etc.). The same principal applies to .zbr files. I tend to view the .zbr file as more of a repository file - at least for the purposes of making game art assets. You can store light info, material info, etc. into the file.
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