Utilities creation in Zbrush

In order to texture our model correctly in Mari, we need to use some maps that help us to take the most of our sculpted details within the color. We will extract some utilities from zBrush to mask out the cavities of our model.

You can also ask to another software to extract these utilities. For example, Substance Painter does an amazing job to calculate automatically these maps for you. What you have to do is just to export all your normal maps from your lower levels out of zBrush.

Then you import them in Substance Painter and place them on the normal map slot. Afterward, just click on Bake, and you get your utilities! I don’t want to overweight the process with a lot of software, so for this workflow I’ll stay within zBrush.

Before you follow these steps, make sure you have polygrouped your models by UV tiles. In the UV tab, select the size of the map you want to export, higher is better.

1. Export the cavities

• Go on the highest level
• In the mask tab, go to mask by cavities
• Click on mask by cavities

• You can adjust the mask, to blur it a bit, using the adjust mask feature
• Isolate the UDIM that you want by CTRL + Shift + click on it
• In the mask tab, click on create alpha 

• In the alpha tab, select your newly created map and click on Flip V 

• Export this map out of zbrush, make sure you name it with the correct UDIM tag.

• Repeat this process for each UDIM

2. Export the curvature

• Go on the highest level
• In the mask tab, go to mask by smoothness
• Click on mask by smoothness

• You can adjust the mask, to blur it a bit, using the adjust mask feature
• Isolate the UDIM that you want by CTRL + Shift + click on it
• In the mask tab, click on create alpha
• In the alpha tab, select your newly created map and click on Flip V
• Export this map out of zbrush, make sure you name it with the correct UDIM tag.
• Repeat this process for each UDIM 

3. Export the AO

• For this one, you don’t want to click on mask by AO on the highest lvl unless you want to kill your computer. Go on a medium resolution level, between 500K poly to 2M poly.
• In the mask tab, go to mask by AO
• Click on mask by AO and adjust the intensity if you’re not satisfied
• You can adjust the mask, to blur it a bit, using the adjust mask feature
• Isolate the UDIM that you want by CTRL + Shift + click on it
• In the mask tab, click on create alpha
• In the alpha tab, select your newly created map and click on Flip V
• Export this map out of zbrush, make sure you name it with the correct UDIM tag.
• Repeat this process for each UDIM 

4. Custom masks

• You can create custom mask directly inside of zBrush to mask out some parts of your model. For example something I like to do is a mask for the inner mouth parts. Another one for interior of the eyes or so to block out the specular later. Either you decide to do them in Mari, or if you like you can do them directly in zBrush.
• Go on the highest lvl
• Hold on the CTRL button and paint your mask on the wanted area
• In the mask tab, click on create alpha
• In the alpha tab, select your newly created map and click on Flip V
• Export this map out of zbrush, make sure you name it with the correct UDIM tag.
• Repeat this process for each UDIM
• Empty your mask and repeat this process for the other isolation masks that you need.

Texturing in Mari

We can now move on to the texture painting in Mari. This process should be very creative. Spend some time to analyze your references. You need to know what will be the different color hues that you’ll paint on your model.

The albedo of a creature is a very living thing. It presents a lot of vibrations, even if the animal you’re making looks flat. Because there is a lot happening on the surface, you need to paint a lot of colors so everything looks natural. You’ll also have to add aging and weather on top of your map. Following, I describe my workflow when it comes to create my albedo.

As opposed to photo projection, I prefer a lot doing procedural texturing so I can take advantage of my displacement.

 Import your sculpted version of your model in your former Mari project.

• Select the new version

• Generate the ambient occlusion for display purpose, or use the one exported from zBrush for masking purpose later

Create one channel per utility

• Import each utilities as a painted layer per channel

Adjust your shader

• Create a normal map channel in sRGB.
• Import your normal map exported from the high definition model in this channel.
• Convert your channel from sRGB to linear.
• In your shader, plug your normal channel in the normal slot
• Empty the former bump slot, the normal map will do the job here

1. Albedo creation

• Create a new channel, call it albedo_tiled.

We now need a good tileable. Most of the time I use a marble texture that a good friend from Weta borrow to me. It needs to have a lot of vibration in it.

• Create a Pattern, under the procedural layers. Import your tileable file in it. Adjust its tile values.
• Create a new layer, use the paint through and paint on seams to clean them.

 Create a new channel, call it albedo.

1. Create the primary colors

• Create a group for your primary colors.
• Share your albedo_tile channel directly into this group. You can do that by holding SHIFT + click and dragging your albedo_tile channel in your primary color group.
• Adjust your color the way you want with some adjustment layers. I like to give more contrast with the level adjustment.
• To create a tint, use a procedural color layer. Select the tint that you want. Put your layer on top of your shared channel in Multiply mode. The more you saturate it, the more your tileable will earn color.

• Create a new group to add another color to your model.
• In this group, share your albedo_tile channel. Add a new procedural color layer in multiply mode. Select a new color.
• Select your group, right click on it, mask and hide everything.
• Now, simply paint with a brush the area where you want the color to appear.
• You can also use your ambient occlusion channel to unmask your second color.

• Right click on your second color, mask, create mask stack.
• In the mask stack, share your ambientOcclusion channel.
• Use a brightness lookup to invert your ambientOcclusion and to contrast it.
• Redo the same process for all the primary colors that you need: share you albedo_tile. Add a procedural color in multiply mode. Make it appears with the mask options. 

2. Secondary colors

We can add more subtle tint. The following steps are more general tips rather than a straight forward workflow. You can follow these step in the order that you want, and adapt them with your own workflow.

• Create a new group, and activate the transfer mode.

• Create a Hue Saturation Value adjustment layer. Give your albedo a new tint by changing the hue.
• Right click on it, mask, create a mask stack.
• In the mask stack, create a procedural noise cloud layer. Play with its size.

• Redo the same process for all the different tint that you want on your albedo. You can use as many HSV as you want to give a lot of vibration to your albedo. Just play with your masks.

• Create a Hue Saturation Value adjustment layer. Lower the value so everything looks darker.
• Right click on it, mask, create a mask stack.
• Share your cavities channel.
• Invert and contrast your cavity mask using a brightness lookup.

3. Tertiary colors and weathering

 To create the tertiary colors, I like to use my utilities as channel mask to paint out some color information.

• Create a new group for the tertiary colors and put it in transfer mode.

• Add an HSL. Rise the luminance and lower the saturation
• In the projection tab, activate the channel projection. Plug in your curvature.
• Invert your channel mask, and contrast it with the curve.

• Select your HSL, right click on it, mask and hide all.
• Select your mask, use the paint tool with a brush that has a bit of texture in it. Start to paint on your model to create some aging effect. Lower the saturation give the creature skin an older look.
• Share your albedo tile channel.

• Create a mask to hide it completely
• In the projection tab, plug in your cavity and invert it.
• Select your shared channel’s mask, paint in the cavities. This will make dirt appearing inside the cavities of your model.
• You can also other type of texture. For example using black marble texture with white veins on a layer that you put in screen mode will add some dead skin effect on top of your albedo.

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