In this chapter we'll look at creating color maps in ZBrush. This is accomplished with a combination of hand-painting textures and projecting texture elements from photography onto the mesh or onto a UV texture map. When painting textures in ZBrush, you can take one of two approaches: UV projection or PolyPainting.
UV projection requires that a mesh have texture coordinates from either ZBrush or an external application. These texture coordinates are called UVs. UVs represent a method for the computer to unwrap a 3D object into a 2D plane so a texture can be applied without distorting. PolyPaint, on the other hand is a Pixologic technology that requires no UV coordinates to function. This can be a huge timesaver as it allows the artist to sculpt, paint, and complete a character in ZBrush without stopping to set up UVs. Once the PolyPaint is completed, the work can be easily transferred into a UV map for rendering in an external application. Both approaches have their strengths, which we'll examine in this chapter.
UV are the coordinates that allow the computer to unwrap a 3D object into a 2D plane for texture application. A good analogy is to think of unstitching a soccer ball and laying it out flat (Figure 5.1); this is a spherical object that has been unfolded into a flat plane. In Figure 5.2 you can see a 3D model of a head and the accompanying UV Texture coordinates. There are several methods of generating UVs using ZBrush's built in automatic mapping tools or laying out UVs by hand in third party applications such as Maya or Headus UV.
UVs help determine the amount of pixel space on a map that is devoted to an area. In the UV layout in Figure 5.3, the head and hands get 25% of the map space while the rest of the body gets 75%. Hand-laying UVs also allows you to determine what parts get the most pixels and importance while smaller objects or areas get less pixel space. In automatic mapping like Automatic UV (AUV) tiles, the texture space is divided evenly over the whole object. This ensures there is no wasted texture space, but it also gives all areas of the character equal resolution, which is not always desirable.
Automatic mapping has the benefit of speed and, in the case of ZBrush's automatic mapping solutions, efficiency, but they also carry drawbacks. Figure 5.4 shows hand-laid UVs are easily human readable. You could open this map in Photoshop and find the seams and the nose. The same map on AUV tiles is unreadable to anything but a machine and impossible to fully edit in Photoshop (Figure 5.5).
ZBrush comes with several UV mapping methods. The two we'll discuss here are AUV and GUV tiles. AUV tiles are the most efficient— they assign the entire UV space to a character. They are not human readable.
Group UV (GUV) tiles are slightly more readable but not as efficient. When faced with a choice between the two, always opt for AUV tiles (Figure 5.6).
Figure 5.6. The same mesh with AUV and GUV tiles; notice how there is no wasted texture space in an AUV tile map comp.
ZBrush sculpting and painting (when using PolyPaint) are UV independent. This means that you could take a character from sculpture through to PolyPainting all before ever laying out UVs. If you then decide to transfer the color to a UV map, you could add UVs in ZBrush or import them into the ZTool. You could also swap UVs with the current set by simply importing a new model with UVs applied. The process of importing and swapping UVs is covered in depth in Chapter 10.
To view your UV corrdinantes in ZBrush you can use the Morph UV function included in ZMapper. Zmapper is a normal mapping tool for ZBrush but it has many other useful functions. For a description of its use for viewing UVs see Chapter 11.
When working with textures and UVs in ZBrush, be aware that there are two separate Texture menus. There is the main Texture menu accessed from the top toolbar (Figure 5.7). This menu allows you to create new textures, rotate and flip existing maps, import and save maps, as well as providing several other tools for working with file textures. See Table 5.1 for an explanation of each menu option. This menu functions similarly to the Brush, Tool, and Alpha menus in that there is a palette for the currently loaded textures as well as several modifiers. The Texture palette itself is accessible on the left of the UI (Figure 5.7).
Table 5.1. The Texture Menu
Menu Option | Function |
|---|---|
Import/Export | Imports and exports texture files. |
Flip H | Flips the currently selected texture horizontally. |
Flip V | Flips the currently selected texture vertically. |
Rotate | Rotates the currently selected texture 90 degrees clockwise. |
Invers | Inverts the currently selected texture. |
Grad | Creates a gradient texture with the color boxes to the right. |
Width | The width value in pixels for the next texture created with the New button. |
Height | The height value in pixels for the next texture created with the New button. |
Clone | Creates a copy of the currently selected texture and places it in the Texture palette. |
New | Creates a new texture with the height and width values set in the sliders as well as the currently selected color in the color picker. |
MakeAlpha | Creates an Alpha from the currently selected texture. Alphas are 16 bit while textures are 8 bit. This will convert the texture to 16 bit and strip all color information. |
Remove | Deletes the current texture from the Texture palette. |
CropandFill | Crops and fills the document window with the currently selected texture. |
GrabDoc | Grabs the document color information and loads it in the Texture palette. |
The second menu is located under the main Tool menu. This is the Texture submenu (Figure 5.8). This menu contains options for working with UV coordinates, switching between UVs and PolyPainting mode, as well as transferring color information from PolyPaint to a UV map (and vice versa). See Table 5.2 for an explanation of each menu option.
Table 5.2. The Tool → Texture Menu
Menu Option | Function |
|---|---|
Colorize | Enables PolyPaint mode |
Grd | Creates a gradient blend between PolyPaint colors—default is on |
EnableUV | Enables the generation and manipulation of UV coordinates |
Disable UV | Deletes the UVs from the currently active ZTool |
Txr>Col | Converts the current texture map to PolyPaint |
Col>Txr | Converts the PolyPaint to a texture map |
Uv>Txr | Reads the color-coded UV groups and converts them to a texture |
Uv Check | Creates a new texture map in which any overlapping UVs are color-code red |
Vertex>Txr | Compares vertex order and polygon order |
UVc | Applies cylindrical UV mapping |
Applies planar UV mapping | |
UVs | Applies spherical UV mapping |
UVTile | Tiles the current texture on all faces |
GUVTiles | Applies Group UV tile mapping |
AUVTiles | Applies Automatic UV tile mapping |
AUVRatio | Controls the ratio of polygon size to texture area assigned |
HRepeat | Repeats the texture horizontally |
VRepeat | Repeats the texture vertically |
AdjU | Adjust the texture in the U direction |
AdjV | Adjust the texture in the V direction |
ApplyAdj | Applies the adjustments from the above sliders |
FSBorder | Sets the width for Fix Seam |
FixSeam | Redraws the UV seams to reduce artifacts on the UV border |
When you texture with UV projection, it requires that the model be temporarily dropped on the canvas in 2.5D mode. You may paint or project from only one view at a time. This is because the computer looks at the color information you have applied to the model and projects it into the UV texture coordinates' corresponding regions. In this section we'll be discussing Projection Master, but be aware that these same techniques can also be applied to PolyPainting.
Projection Master allows you to convert the current canvas view of your model into Pixols. This process is called "dropping" the model to the canvas. This will allow you to use the 2.5D illustration and sculpting tools on a 3D model that is temporarily frozen in a single view and converted to Pixols. When you have finished working on the view, Projection Master will pick up the model from the current view and project the Pixol painting strokes to the model. If you were sculpting, the detail would be projected into the current mesh; if you were painting, the color strokes would be projected into the UV texture map or onto the PolyPaint surface. Projection Master does this by sampling the RGB, Material, and Depth values for each Pixol on the canvas and transferring that information to the corresponding pixels on the color map or polygons on the 3D surface.
Normally in Projection Master you rotate so that the area you want to work on is directly facing you, dropping the model with the Projection Master button, painting or sculpting, then picking up again. This process is repeated as much as needed by rotating small increments around the surface.
Start Projection Master by clicking its button in the upper left of the screen
- Color
Specifies that the color information you paint in Projection Master will be applied to the model when it is picked up. The option Shaded will "bake" the current surface shading into the model as well as the color information. Material will bake in the material settings. These options apply to PolyPaint or UV projection.
- Double Sided
Projects your painting or sculpting through to the other side of the model. This is best used on a symmetrical object when you have snapped to an orthographic side view. Remember that Shift-dragging in the document window while a tool is in Edit mode will snap it to the closest orthographic view.
- Fade
When Fade is turned on, any texture or color painted on the model will fade as the surface turns away from the surface normal. The effect is similar to spraying an airbrush directly at a surface; any areas that curve away get a lighter coat than those facing you. With Fade off, all surfaces get a solid coverage of the texture or color.
- Deformation
Applies any sculpting strokes to the mesh. These are projected into the mesh at pickup and deform the actual geometry. For deformation to function, there must be enough resolution in the number of polygons to support the level of detail you are attempting to achieve.
- Normalized
Takes into account the normal of the surface when projecting sculpted details. When Nomalized is off, all sculpting is projected directly back in ZBrush with no attention given to the curvature of the underlying surface.
With the model now dropped to the canvas, you may use any of the 2.5D brushes available under the tool menu. The difference here is that since you used Projection Master to "drop" the model, you can pick it up again and apply the changes you made. To pick up from Projection Master, use the G hotkey and click the Pickup Now button.
Note
It is important to understand that Projection Master techniques used for UV projection are also applicable to PolyPaint. The only difference is the way the color information is interpreted by the computer once the model is picked up from Projection Master. Projection Master is by no means limited to only UV projection painting. By its nature, however, it will always require that you temporarily drop the model to the canvas.
By using a ZScript called ImagePlane3 reference images may be imported directly into the ZBrush workspace for use as a guide while sculpting or as a texturing tool. Included on the DVD is ImagePlane3. Install the script in your ZStartup/ZPlugs directory and launch ZBrush.
PolyPainting is an approach to texturing that lets you color a model by applying a single RGB value to each polygon vertex. This allows you to texture without the need for UV coordinates. By applying color directly to vertices, you also avoid the need to drop the model to the canvas while painting. All texturing can be done in Edit mode, and you can freely rotate around the model.
Because the color is applied to each vertex, this means the resolution of the resulting texture is directly linked to the number of subdivision levels in the mesh. This means that a model of several million polygons can have a sharp, clear texture while a lower resolution level will have a softer texture with less detail.
PolyPainting cannot by itself be exported. To create a map for use in a third-party renderer like mental ray, you need to bake the PolyPainting into a UV texture map. Luckily, this is a simple process covered later in this chapter. The resolution of the color map is again linked to the resolution levels of the model. If you want the equivalent of a 4096×4096 map, you will need 16 million polygons of subdivision.
If you plan on rendering your character in another application, you must eventually use a UV texture map. This can be created from your PolyPainted texture (as we discuss later in this chapter), or you could start with a UV map. Figure 5.10 shows a character painted with PolyPaint but rendered in Maya.
Now that you understand the two methods of painting texture in ZBrush, let's explore color theory. This section focuses on painting a creature skin from scratch, but there is often more to painting than just laying down colors in a random pattern hoping for a good result. By understanding some basic color theory, you can make educated decisions on what color to select and where to place it on your character, thus painting extremely realistic skin textures quickly. For this paint scheme, we'll use a limited palette. Table 5.3 shows the colors that we'll use to paint this particular skin tone.
Table 5.3. Hues Used in the Paint Job
Color | Name | R | G | B |
|---|---|---|---|---|
 | Red | 255 | 2 | 2 |
 | Yellow | 255 | 255 | 128 |
 | Blue | 0 | 128 | 255 |
 | Warm brown | 64 | 0 | 0 |
 | Cool brown | 72 | 63 | 53 |
 | Gray | 100 | 123 | 122 |
 | Olive | 134 | 129 | 89 |
Color theory constitutes a book unto itself, but some of the most important things to note are in this section.
The color we see can be organized into a color wheel, which consists of the Primary, Secondary, and Tertiary colors. Primary colors consist of red, yellow and blue. These colors cannot be created by mixing any other colors. The secondary colors are created by mixing two primary colors: red and blue make purple, yellow and blue make green. Tertiary colors are created by mixing a primary and secondary color like blue-green or yellow orange. By understanding a few color concepts you can make educated decisions about what colors to put down on a character when painting a skin.
Temperature refers to the relative warmness or coolness of a color. Red is "warm" compared to blue. A color can be warm or cool depending on what is mixed with it; red, for instance, becomes warm when mixed with yellow, or becomes cool when mixed with blue.
Hues that move toward the red area of the color wheel are said to be "warmer" than those toward the blue, or "cool," side. By placing two colors near each other with different temperatures, you create what is known as temperature contrast.
In practical terms, try painting a cool color into recessed areas and a warm color on raised areas. This contrast helps to emphasize the form as well as create visual interest.
Saturation is the relative intensity of a color. You can reduce a color's saturation by moving the color picker toward gray. This is called neutralizing the color and helps create a muted color (Figure 5.12).
You can see that the color selections in Table 5.3 are a limited palette, especially when compared to the look of the final painted skin. The power of these few color choices comes from the phenomenon of optical mixing. Optical mixing refers to a method of creating a secondary color by placing its two primary components close together. This can be seen in the Pointillist paintings, where tiny dots of color are used to create the entire painting. For example, with stripes of yellow and blue placed close together, the hues combine in the eye to cause the viewer to see green (Figure 5.13). To see this at work in a more practical setting see Figure 5.14. The same approach can be seen in painting where a stroke of one color is dragged across another color. The two colors seen in such a way give the impression of a third color.
Portrait painters have known for centuries that the face can be broken into temperature regions—areas that have a defined relative warmth or coolness. This is due to the translucency of the skin and the quality of the tissues, as well as the relative closeness of muscle and bone to the surface. In Figure 5.15, I have broken down the relative temperature relationships between the regions of the face of the character we'll paint later in this chapter. In general, on a light-skinned individual the brow takes on a yellow or golden cast, while the cheeks, nose, and ears are warm, red hues. The mouth and jawline are cooler blues. In men, this is even more pronounced than in women because of the beard line and the presence of hair in the follicles under the skin.
The technique we'll use to paint this creature skin is based on airbrush paint techniques from the practical makeup effects world. An airbrush sprays paint on a surface in an adjustable fine mist. Changes to the brush can cause paint to be applied in broken-up, spotty patterns. This kind of paint application is ideal for optical mixing and for giving the skin a realistic look. Look at a close-up photograph of a face and notice how it contains many colors and temperature variations. It is not a single flat hue.
Figures 5.16 and 5.17 illustrate this technique applied to practical creature effects. Just as ZBrush allows us to sculpt with real-world style tools and techniques, it also allows us to paint this way as well. Using an airbrush tool in ZBrush helps us apply some of the same techniques and approaches used to paint prosthetics and animatronic creature skins.
We'll use a custom brush for this tutorial. This brush is designed to behave in a manner similar to an airbrush. By using a spray stroke and a paint spatter alpha, we can apply color in broken patterns similar to the airbrush described in the previous section. This ability of ZBrush to mimic real-world tools helps us utilize traditional techniques to achieve great results in a digital medium. To create your airbrush, follow these steps:
Select the Standard brush from the Brush palette. Make sure that ZAdd, ZSub, MRGB, and M are off and RGB is on.
Open the Stroke menu from the top of the screen. Dock the Stroke menu to the right of the screen and click the Radial button. Select a spray stroke. Be careful to select Spray and not Colorized Spray. Scroll down in the Stroke menu to the options (Figure 5.18). Turn Color and Flow down to 0. If Color is above 1, it will modulate the intensity of the color you have selected, which can cause problems when you're trying to establish color temperatures.
The spray brush you just created will put down color in a broken, random pattern similar to those created by an airbrush. See Figure 5.19 for a sample of the brush stroke.
You can save this brush as a preset by clicking on the main Brush menu and selecting Save As. Save the brush in your BrushPresets folder at
Program FilesPixologicBrush3StartupBrushPresets. With the brush saved here, it will always load with ZBrush, thus giving you easy access to this custom brush variant. Another option is to save the brush as a macro. For more information on creating macros, see Chapter 12.
Note
Using the information we now have about color temperature, we'll begin to block in those areas on the ZTool. Use the custom spray brush and be sure to keep your paint job overstated and vibrant at this stage. This will be the lowest layer of many layers of color, so the brighter it is now, the better it will look when under several more layers of color. This entire painting process is shown in a video on the book's DVD.
Begin by establishing an overall base color for the head. Click Tool → Texture and turn on Colorize. Click the Disable UV button to delete the UVs from the current model. This will free up system resources since ZBrush will not have to track UVs while you PolyPaint. UVs can always be reimported later. This enables PolyPainting. We want to select a base color on which to paint. White is a poor base color as it makes all other colors look too bright. It is easier to paint on a hue that represents the final look we are striving for. Open the main Color menu and click the SysPalette button (Figure 5.20). From the color picker select a light peach hue something near RGB 251 228 198. This is a good base for a lighter skin tone.
With the color value selected, make sure RGB is on for your current brush. Choose Color → Fill Object. This will fill the object with the base tone selected.
The next stage is to spray in the warm regions of the face. Give the head an overall light pass of red, concentrating it in the cheeks, nose, and neck (Figure 5.21). Also touch the ears with red. Ears have a tendency to be warm (Figure 5.22). When painting, adjust the RGB intensity slider. For most of the painting, I keep the slider around 25. You want to keep the colors somewhat transparent so that they will mix better as they are applied over one another.
After this pass of warm hues, select blue RGB 1 128 255, and use the same spatter brush block in the cool regions of the face (Figure 5.23). The area around the mouth, chin, and jawline has a tendency to be cooler. Spray blue in these areas as well as the eye sockets (Figure 5.24). Also use the blue in the recessed regions, such as the neck and recesses of the ears.
The next color pass is yellow. Select yellow RGB value 255 255 128, and apply it to those areas of the skin that are thinner, and areas where the bone is closest to the surface, such as the forehead, temporal ridge, chin, and clavicles. Notice how the yellow takes on a green cast in the areas where it meets the blue (Figure 5.25). Use the yellow sparingly.
Now that we have laid out the temperature regions of the face, we can move on to what is called the mottling pass. This is sometimes called the noodling pass. The point of this color pass is to break up the previous layers with little squiggly lines to help simulate the fibers and tissues of the deep skin layers.
The mottling pass is an overall coverage of tiny, broken-up squiggly lines. These will look strange now, but when the next step covers the entire head with a light version of the flesh tone, it will break up the saturation of different areas of the face and help create a sense of depth and translucency to the skin.
Note
Be aware that these early stages of the paint scheme will look overstated and odd. This is intentional; the next passes of color will partially obscure these layers. The more overstated the under-painting is, the better it will show through the subsequent layers. For example, some classical painters even started portraits with a green under-painting. This green tone would be visible in the shadows after all the skin tones were applied, thus creating a lush shadow and a sense of temperature contrast between the light and dark areas.
Begin by selecting a freehand stroke and alpha 01. Lower your draw size and select white as your color. Begin to make small, tight figure-8 patterns on the skin. Try to be as random as possible, keeping the patterns tight (Figure 5.26). You can vary the patterning around the eyes and lips, making those areas tighter, and make the patterning wider on the head and temples. Experience will dictate how different patterns appear once the painting is completed.
I recommend doing as much of this as possible freehand, but you may choose the vein alpha 22 and a dragRect stroke to fill in large areas like the neck and back of the head (Figure 5.27).
Once this mottling pass is completed, your character should look like Figure 5.28.
At this stage you want to unify the colors from the previous steps with a light coating of the base color. This is called a wash, after a traditional painting technique where a color is diluted to make it more transparent. This is also a good point to change to a MatCap skin material. We didn't use a skin material before now so we could get a clearer picture of the primary colors and their intensity as we painted. We may now more easily judge the overall effect with a translucent material.
Select the Spatter brush. Select the base color again. There should be an area on the head with the base color exposed. The easiest way to select it again is to click and drag from the active color box to a point on the model. The current color will be sampled from this point.
Spray this base color over the character with a low opacity and RGB intensity of about 10 (Figure 5.29).
Select Skin04 from the MatCap material menu. Click the Material menu from the main menu and click Modifiers. From the rollout options, lower Opacity to around 70 (Figure 5.30). The skin will suddenly take on a much more realistic translucent property (Figure 5.31). This is ideal for the next fine-tuning steps.
At this stage you will want to adjust the color temperature of certain areas by spraying lighter spatter passes of warm and cool colors. The previous stage of coating the head with a pass of the light flesh color both unified the paint scheme and muted the overall temperature modulations. At this stage we'll also do some shading with cool browns. This will help accentuate the forms of the head.
Selecting Red and using the Spray brush, add more red to the area around the horns. This skin should look ruddy and raw since the horns are pressing through the skin. Add this red to the tips of the ears to increase the warmth of these areas. Spray red into the lip and mouth area and the corners of the nostrils (Figure 5.32).
Switch to RGB 0 128 255 primary blue. Lower the RGB Intensity value to around 9 and spray over the lips, confining the spray pattern to the lips themselves, trying not to overpaint onto the surrounding skin. Take this opportunity to spray blue again into the eye sockets and hollows of the ears (Figure 5.33).
Switch back to Alpha 01 and a freehand stroke. Turn down the draw size to 5, and with blue still selected, create a light veining pattern at the temples. This will help give the impression of blood vessels beneath the flesh (Figure 5.34).
At this point the paint scheme is ready for contouring. Contouring consists of light shading around the major forms to help define them and bring the structure out. Select a cool brown, in this case RGB 72 63 53, and lower the RGB Intensity so the color is very faint. Select the Spray brush and lightly shade around major forms like the collarbones and scapula (Figure 5.35). Spray this color under the cheekbones and in the hollows of the eyes.
The final stage is to paint a slightly darker version of the base color into the recesses of the wrinkles. To do this we'll use cavity masking. Click Tool → Masking from the main menu and press the Mask By Cavity button
Click and drag from the active color swatch to the character head. This will select the underlying color. Open the system palette and neutralize the color by reducing its saturation, which you can do by dragging the slider down toward gray (Figure 5.37). It creates a chromatic gray or a gray with some sense of color. Using hues like this helps keep the color palette of the character skin more natural and slightly muted.
The head is cavity masked although the masking is not visible. Using the Spray brush with RGB Intensity low, spray into the deep recesses. The cavity masking will protect the raised portions from being colored.
For the stinger we'll use Projection Master. This is because using Projection Master allows us to use the 2.5D brushes which are usually only used on the canvas and not on a 3D model. Projection Master allows us to temporarily drop to the canvas and treat the model as a 2.5D illustration. In this case we'll use the Deco brush. The Deco brush creates long, tapered calligraphic strokes as you saw in Chapter 4 (Figure 5.38). In this case we'll use it for color and not sculpting.
Since we'll be painting only on the horn, let's mask the skin area we don't want to paint. Select the Lasso tool on the right side of the screen. Using Ctrl+Shift-click, draw a hide marquee around the head ending just short of the stinger.
Drop down a few subdivision levels and hide the faces up to the horn. Enter Frame mode to easily see the faces. Turn on Point Select. Hide the faces (Figure 5.39). Mask the stinger and Ctrl+Shift-click the background to show the rest of the head again. Invert the mask by Ctrl-clicking and step back up the subdivision levels. If you still have the polygroups from the sculpting phase of this character, use them to isolate the horn from the head and mask the skin. If your mask appears too light, make sure the RGB slider is set to 100. If this value is lower, the mask will be faint to invisible.
Orient the character head so the stinger takes up as much of the document window as possible. You can zoom out from the stinger using the Zoom button on the right side of the screen
Drop the ZTool with Projection Master by clicking the PM button or pressing the G hotkey. The canvas is now in 2.5D mode.
From the Tool palette select the Simple brush. Turn off ZAdd so only RGB is on. Select a cool white (RGB 240 241 244) and paint the stinger with this base color. Next, select a cool dark brown (RGB 72 63 53) and paint around the base and tip of the horn.
From the Tool palette select the Deco brush. Turn off the texture in the Texture palette. Turn down the draw size, and with the same brown selected, draw some strokes down the length of the stinger.
Select the base color again and drag strokes of the lighter color into the bark stripes at the top and base of the horn (Figure 5.41).
Select the Blur brush from the Tool palette. Make sure RGB is on and stroke over the deco strokes. This will soften the strokes and blur them slightly (Figure 5.42).
Select the Simple brush and Alpha 01, then lower the draw size to 10. Select a cool brown and paint a light squiggly pattern (Figure 5.43). This squiggly pattern is inspired by photo references I have seen of bison horns that feature this light patterning in the grain of the bone. This is pushed back with the blur brush and a light intensity pass of the original cool white.
Continue by misting the original cool white back over the horn with a very low intensity. Also add a touch of yellow and blur again. Pick up the ZTool from Projection Master by pressing the PM button or the G hotkey. Make sure that Double Sided is on; this will create a slight stretching at the top and bottom of the horn. To fix this, simply reorient and drop again to paint the top and bottom of the stinger. Be sure to turn off Double Sided when working on these areas so that your texture does not project through, thus damaging the work on the other side.
You have now completed painting the creature skin and stinger using PolyPaint freehand techniques as well as Projection Master and 2.5D brushes. In the next section, we'll address the side horns of this creature with a slightly different approach.
ZAppLink is a free plug-in for ZBrush available from Pixologic.com. It is a free add-on to the program and allows you to seamlessly integrate ZBrush's painting tools with Photoshop. This program will allow you to use all your favorite Photoshop brushes and filters in conjunction with ZBrush.
Install ZAppLink by following the instructions included with the download. To see the plug-in, select Document from the main menu. To launch the program, click the ZAppLink button. In the section called ZAppLink Properties (Figure 5.44), click the ZAppLink Properties to open this menu, click the name to unroll the menu and access the options]
The ZAppLink Properties window contains the options for storing views of your model. Views allow you to store a model's position on canvas so you can use layers in Photoshop. We'll cover views later in this section. For now let's look at ZAppLink as a connection to Photoshop. Load the character model from the previous section. Draw the Stingerhead on the canvas and enter Edit mode. Orient so the horns are visible from the top, as shown in Figure 5.45. Mask the horn area and invert so the horns are now unmasked. Load ZAppLink by pressing Ctrl+Shift+S. Photoshop will now open (or the program you have on your system that opens PSD files).
Since we only want to color the horn, mask out the rest of the head. The simplest way to do this is to mask the horns and then invert. Orient the head on the canvas so the top view of a horn fills the screen. Once the head is placed, you will load ZAppLink by pressing Ctrl+Shift+S or by opening the document window and pressing the ZAppLink button
Click the Drop Now button and Photoshop will load with the ZBrush document as an open image (Figure 5.47).
The ZAppLink document contains three layers (Figure 5.48):
The top represents the shading from ZBrush and should not be altered. You can turn this one and off to see the color information with no shading information.
The second layer is the ZBrush document window image with a layer mask. This layer mask simply cuts off any overpaint that is not directly on the model.
The third layer is simply a background. When editing, you can change layer 2 or add new layers, but you must collapse your changes into layer 2, always preserving the layer mask when asked. You must have the original three layers before returning to ZBrush.
Open an image of a horn in Photoshop, copy and paste it over the ZAppLink image of the document window. Erase the edges of the image so it blends off (Figure 5.49).
When you have completed editing in Photoshop. collapse your new layers down to layer 2. Before collapsing to layer 2, Photoshop will ask if you want to preserve the layer mask; select Preserve. Be sure not to click Apply. Now save your document and return to ZBrush.
You will see a ZAppLink prompt asking if you want to reenter ZBrush or return to the external editor. Select Re-enter ZBrush and, on the following menu, select Pickup Now. The photo reference that was placed in Photoshop will now bake into the PolyPaint of the model. You can rotate to the other horn and repeat the process. ZAppLink is not limited to simply projecting photo references. You may also use the entire suite of Photoshop painting tools.
By continuing to rotate around the head, dropping and projecting a reference in ZAppLink, you can build up a base texture. Continue to adjust the color of the horns in PolyPaint and sample colors directly from the canvas using the projected photo reference as a guide.
Figure 5.50. A selection of details that help push the realism of the head include spider veins around the nose and eyes.
Let's make some final tweaks to take the paint job one step further. Try using cavity masking (Tool → Masking → Mask By Cavity) and paint a cool brown with a very light intensity into the recesses and skin details. On this character, I selected a purple hue and added some tiny veins around the nostrils, eyelids, and horns (Figure 5.50).
That completes painting the creature skin. By combining Projection Master, ZAppLink, and PolyPainting techniques, you have painted a detailed character from scratch (Figure 5.51). In the next section we'll discuss how to bake this PolyPainted texture into a UV map so this character can be rendered outside ZBrush.
Once you have completed your PolyPaint, you will at some point want to bake it into a UV map if you plan on rendering outside of ZBrush (Figure 5.52). This simple process is outlined in the following steps:
Load the PolyPainted ZTool.
Step up to the highest subdivision level. With the texture selected in the Texture palette and displaying on the model, open the Tool menu, click Texture, and press the Tx>Col button. This will convert the current texture to PolyPaint data. If you turn off the texture in the Texture palette, you will see that the color still displays on the surface since the data is in PolyPaint form.
Step down to level 1. From the Tool menu click the Import button and import the UVed model into the existing Ztool. Importing a model with new UVs into an existing ZTool is covered in Chapter 10.
Create a new texture at the desired resolution in the main Texture menu.
Under Tool → Texture, click the Col>Tx button to convert the PolyPaint to UV texture information.
Note
This process also allows you to transfer textures from one UV set to another by converting a UV texture map to PolyPaint, which you do by clicking the TX>Col button. This workflow is used extensively in my own production pipeline to allow UV changes after a texture has been created.
ZAppLink allows you to store a Ztool's position on the canvas for later recall. To do this, you must store views under the Document → ZAppLink Properties menu. To store a view, position the model facing the canvas in the center of the screen. Open the main document window and click the ZAppLink Properties menu to open it. Click the Front button to store this view. Rotate to the side and press the Right button to store the right-side view. Notice that ZBrush will automatically store the opposite view for you; in the top view, for instance, the bottom view is automatically stored. If you need to clear a view, click the Clear button. If you need to save the views file for later use, click Save Views.
Now when you open ZAppLink, all the views will export as a single document (Figure 5.53). To work on a single view at a time, Alt-click the layer you want to work on to hide all other layers. Then turn on the visibility for the shading layer directly above it. When done, save your image and return to ZBrush. When you return to ZBrush, any changes made to any of the layers will update on the corresponding side of the ZTool. Click Accept for each view to keep the texturing information; otherwise, click Cancel.
