Module 12

-Class 12-

OVERVIEW

• Painting Your Model - Different Approaches
• UV Mapping
• Polypainting
• Masking Techniques for Painting
• Converting Polypaint to Textures
• Spotlight
• Painting Your Creature Bust

Painting Your Model - Different Approaches

Texture Mapping

The Kotelnikoff_Earthquake.ZPR project found in Lightbox revealing the 2D texture map alone and mapped onto the model.

Polypainting

A cube with few subdivisions can hold very little Polypainted (and sculpted) detail.

A cube with more subdivisions can hold more polypainted (and sculpted) detail.

UV Mapping

UV mapping refers to the process of projecting a 2D image (texture map) onto a 3D model. UV mapping is a necessary step in Texture Mapping and involves unwrapping a 3D model into UV coordinates. UV mapping can be a manual process (done by a Modeler or Texture Painter) but can also be an automated one, or a combination of both."

Image courtesy of Wikipedia

UV coordinates are points on a 2D grid that correspond with the vertices that make up a model.

The "U" in "UV" refers to the horizontal direction and "V" refers to the vertical direction. One UV Tile ranges from a value of 0 to 1 in both the U and V directions. A UV coordinate is represented like this: Uvalue, Vvalue. So (.5, .5) would refer to a coordinate in the middle of the UV Tile.

Seams are cut along a model's edgeloops to allow the 3D model to be flattened. It's common to cut a model into pieces in order to avoid it being stretched when it is flattened into UV coordinates. Think of the way clothing is constructed from flat panels. In 3D terminology, each panel would be called a "UV Island" (or shell). ZBrush has somewhat limited control over UV Mapping, but it is possible to utilize polygroups to help break your model's UV coordinates into user-defined islands.

UV Master

Using UV Master (Zplugin > UV Master)

1. Set Tool > Geometry > SDiv to 1

2. (Optional) Work on Clone
1. This is not necessary but advised. It will create (and switch to) a new ZTool generated from your current Subtool at its current subdivision level.

3. (Optional) Enable Control Painting
1. This will allow you to suggest where ZBrush puts seams on your model through painting red (to protect areas from seams) or blue (to attract seams). It's best to have seams in inconspicuous areas and to avoid putting a seam right down a character's face, for example.

4. Unwrap

5. (Optional) Check seams. Double-check where ZBrush cut seams.

6. (Optional) If you worked on a clone, click Copy UVs in the Utilities section of the plugin, then select your original Subtool and press Paste UVs.

7. Celebrate how easy that was!

POLYPAINTING

To polypaint your model you need to do the following:

1. Make sure there are sufficient polygons to support the detail you want to paint.
2. Turn on Colorize in the Tool > Polypaint sub-palette

3. Turn off ZAdd or ZSub to avoid sculpting your model as you paint

4. Turn on RGB
5. Pick a color and paint

It's that easy! Later in the module, we'll look at how to convert your polypainting to a texture and export it.

MASKING TECHNIQUES FOR PAINTING

Mask by Cavity (Tool > Masking)

1. Press Tool > Masking > Mask by Cavity > Mask by Cavity.

2. Press Tool > Masking > Inverse (or press Ctrl, then click off of your model) to invert the mask.

3. (Optional) If you're mask is picking up too much detail and coming out noisy, one thing you can do is adjust the Tool > Masking > Mask by Cavity > Blur setting and regenerate your mask. The issue with this tool is that it can water down details, making them disappear as you increase the value.

4. (Optional) Press Tool > Masking > BlurMask (or press Ctrl, then click on the mask) to smooth out your mask. Because the resolution of your mask is dependent on the resolution of your model, sometimes you can see stairstepping, or pixelated edges, on the mask. If you find that the blur is too strong, adjust the value of Preferences > Transpose > Mask Blur Strength.

5. (Optional) Adjust the Cavity Profile graph for different results.

6. Sometimes the mask can be distracting. To turn of the visibility of the mask, go toTurn off Tool > Masking > ViewMask so when you paint, the mask isn't visually distracting.

7. Paint!

Mask by Smoothness (Tool -> Masking)

Converting Polypaint to Textures

To bake polypainting into a texture map:

1. Set the size you want for your final map. Go to Set Tool > UV Map > UV Map Size and set the value to 4096 to create a 4096 x 4096 map (also called a "4K map").

2. Set Tool > Geometry > SDiv to the highest level.
3. Press Tool > Texture Map > Create > New From Polypaint.

"Map resolution" refers to the pixel dimensions of the image used for your texture map. Use a square resolution such as 256 x 256, 512 x 512, 1024 x 1024, and so on. For an entire creature bust, like we are creating in this class, a 4K map should work well.

Importing and Exporting Textures from ZBrush

To import a texture from your computer's hard drive, follow these steps:

1. Go to Texture > Import
2. Then go to Tool > Texture Map. Select the imported texture by clicking on the thumbnail. The Texture On button must be turned on in order to see the texture on your model.
   
   

To export a texture from ZBrush to your computer's hard drive:

1. Press Tool > Texture Map > Clone Txtr
   
   


1. The Clone Texture button will create a copy of the currently selected texture (as displayed in the Texture Map thumbnail) and put it in the main Texture palette. It is necessary to clone a texture like this if you wish to export it from ZBrush. (Courtesy of docs.pixologic.com)

2. Go to Texture > Export. You'll see a field for naming your file and selecting a file type.
3. Name your file and choose a file type.

7. SpotLight

SpotLight is a texture-projection system that allows you to paint your models using 2D images or textures. These "textures" are different from texture maps in that they are the source images used to create the texture maps you would export for rendering. SpotLight also includes many controls for editing and preparing your textures to paint with as you work.

One benefit to using images to paint textures is that you can get a lot of detail for free. The precise details found in nature photographs, for example, spare us from having to them by hand. Take this dirt image for example (found in Lightbox); it can be used as a layer to paint skin, and the light and dark variations mimic what you would see in actual skin.

Get creative with how you choose your sources of texture. A simple Google image search of "pancake texture" yields a slew of interesting images that could be used to produce skin effects.

Working with SpotLight

1. Load your model and make sure you have enough subdivisions to capture the level of painted detail you want. SpotLight works based on polypainting, so the same resolution concepts apply.
2. Load a texture from file or Lightbox.
3. With the texture selected, go to Texture > Add to SpotLight

4. Manipulate the loaded image. (See section on SpotLight Dial below.)

5. Enter 3D Paint Mode by pressing "Z" on your keyboard and paint! Press Z again to bring SpotLight back if you wish to further edit the image.

6. Press Shift+Z to turn SpotLight off. You can also turn it off from the main Texture menu.

SpotLight Dial

SpotLight is constructed around a widget called the SpotLight Dial which is used as a manipulator to edit things like Hue, Saturation, and Value.

(The following descriptions for the SpotLight Dial tool are courtesy of pixologic.com)

1. Rotate

You can click on and drag the rotate icon in both a clockwise and counterclockwise direction in order to rotate an image. By holding down the Shift key while rotating the image you can snap the image to the notches seen on the inner part of the SpotLight dial.

2. Scale

You can click and drag the Scale icon in both a clockwise and counterclockwise direction in order to scale an image. By default, the width and height will remain proportional. Using the Scale icon while holding down the Ctrl key (Windows) or the Command key (Mac) will scale the image non-proportionally.

3. Pin SpotLight

The Pin SpotLight allows you to choose and constrain what part of an image you want to use at the start of your stroke. The portion that will be used is located under the center of the SpotLight dial. To put it simply, if you were to place the dial over the eye on a photograph of a face, you could paint that eye over and over again in different locations on your model.

4. SpotLight Radius

The SpotLight paint mode spot looks very much like the circular light you might see a flashlight make when shined on a wall. When in SpotLight paint mode, the SspotLight will reveal a certain portion of the image your cursor is currently over.

1. By default the SpotLight Radius is set to 0, which means when you enter paint mode you will see all the images you currently have loaded in SpotLight.
2. You can click on and drag the SpotLight Radius icon in a clockwise direction in order to increase the size of this radius tool. Dragging in a counterclockwise direction will decrease the radius of the SpotLight back to 0.
3. The SpotLight radius does not control the amount of the image you paint and sculpt onto a model. Those continue to be controlled by your Draw Size, RGB Intensity, and Z Intensity. SpotLight simply gives you a preview of what part of an image you are about to paint and sculpt with.

5. Opacity

You can click on and drag the Opacity icon in both a clockwise and counterclockwise direction in order to increase or decrease the opacity of all of images loaded within SpotLight.

Note: The amount of opacity applied to your images will not affect how much of the image is painted and/or sculpted onto your model. This is instead controlled by the RGB Intensity and Z Intensity sliders. To reduce an image's effect relative to the Intensity settings, use the Fade feature instead.

6. Fade

In SpotLight you can layer images on top of one another in order to mix and blend the images as you paint and/or sculpt them onto your model. The Fade feature will control how much influence a specific image will have in a stack of images.

7. Delete

Clicking the Delete icon will remove the active image from the SpotLight interface.

8. Flip H

Clicking the Flip H icon will flip the active image horizontally.

9. Flip V

The Flip V icon will flip the active image vertically.

10. Restore

You can restore an entire active image back to its original state by clicking on and dragging the Restore icon in a clockwise direction.

11. Contrast

To increase the contrast for an entire image, click and drag the Contrast icon in a clockwise direction. To decrease contrast for an entire image, click and drag the Contrast icon in a counterclockwise direction.

12. Saturation

To add saturation to an entire image, click and drag the Saturation icon in a clockwise direction. To reduce saturation in an image click and drag the Saturation icon in a counterclockwise direction.

13. Hue

To change the Hue for an entire image click on and drag the Hue icon in a clockwise direction.

14. Intensity (or Value)

To increase the intensity for an entire image, click and drag the Intensity icon in a clockwise direction. To reduce the intensity of an image, click and drag the Intensity icon in a counterclockwise direction.

Note: When the intensity of an entire image reaches pure black the image will become completely transparent.

Painting Process

This process focuses on creating a realistic skin for a creature. Some artists prefer to entirely hand paint their models without using texture images, whereas some artists only use images. A combination of the two is likely.

1. Use Color > Fill Object to cover your creature in a base skin tone. Generally, for a realistic skin tone, you'll want to start with a mid-value, muted tone.

2. Switch to SkinShade4 material or MatCap White01. These are good materials for painting because they have a light base and display color well.

• With the SkinShade4 material selected, try turning the setting Material > Modifiers > Ambient up a little, and the setting Material > Modifiers > Specular down to make it easier to see your painting.

3. Add skin variation. In both cases you'll want to use this as an opportunity to start defining regions of color on your creature. For example, the face may be darker than the forehead and a transition from bottom of the face to the top needs to be accounted for. Or the top of the cranium might be dark purple and transitions to light blue when to come down to the neck. In both of the following techniques, use your brush as if you were scribbling on the surface of your model. If you were to evenly paint back and forth across your model, you risk making it look as if it were mechanically painted.

Mottling: This is a hand-painted approach. The term "mottled" refers to irregular patterns or blotches that we see on our skin, such as you might find on your palm. Create a mottled effect by using the Standard brush with either the ColorSpray stroke or the Spray Stroke. Adjust the settings of each stroke as needed from within the Texture palette. In this image, you'll see some mottling that was achieved by using a slightly darker and more yellow color than the base coat.

1. SpotLight: This is an image-based approach. Use the techniques you learned previously in this module to add skin variation to your creature.

4. When painting near the center line of your creature, turn off X-symmetry. Don't forget to turn it back on when you move away from the center.
5. Paint any patterns or color regions you want on your creature.

6. You might also try emulating a spray-painting effect mastered by Steve Wang, a legendary special effects artist—though he does use an airbrush rather than a computer to achieve this look. With the Standard brush, Spray stroke (with the Placement setting set to a very low value of .09), and Alpha 46 lightly paint in a netting pattern over areas of your creature. Applying this pattern gives the surface a beautifully organic and uniform feel and adds a sense of depth to the skin.

7. There are times when you'll want to see your painting's true colors without light or shadow obstructing them. Switch to the Flat Color material for this. It's not uncommon to do a considerable amount of painting with this material selected.

8. Apply any masking techniques discussed earlier in this module.
9. Finish off your creature with a light coat of color to tie everything together. A good combination of tools to use here is the Standard brush, Spray stroke (default settings), and Alpha 08 tools. This gives you a nice spraying effect similar to what you would get with an airbrush.

Homework:

1) Continue to work on characters/creatures