ZBrush 4: Modeling a Creature with ZSketch

Exclusive offer: get 50% off this eBook here
ZBrush 4 Sculpting for Games: Beginner's Guide

ZBrush 4 Sculpting for Games: Beginner's Guide — Save 50%

Sculpt machines, environments, and creatures for your game development projects

$26.99    $13.50
by Manuel Scherer | April 2011 | Beginner's Guides

Since ZBrush was released, it dramatically changed the way game art is created. It is unmatched in its speed for creating highly detailed models and thus, is widely used in the games and film industry. We could even say that if you want to be a game artist today, ZBrush is considered a standard. A few years ago, ZBrush was used only for organic modeling. With ZBrush 4.0 this changed dramatically and you can now sculpt mechanical spaceships as well as organic creatures.

In this article by Manuel Scherer, author of ZBrush 4 Sculpting for Games: Beginner's Guide, we'll cover:

  • Organizing a complex mesh using armatures
  • Freeform sculpting with ZSpheres/ZSketch
  • Modeling for animation
  • Mesh conversion with Unified Skinning

 

ZBrush 4 Sculpting for Games: Beginner's Guide

ZBrush 4 Sculpting for Games: Beginner's Guide

Sculpt machines, environments, and creatures for your game development projects

        Read more about this book      

(For more resources on the subject, see here.)

What the creature looks like

The Brute is a crossbreed between a harmless emu and a wild forest bear. It is a roaming rogue living in the deepest forests. Only a few people have seen it and survived, so it's said to be between three and eight meters high. Despite its size, it combines strength and agility in a dangerous way. It is said that it hides his rather cute-looking head with trophies of its victims.

ZBrush 4: Modeling a Creature with ZSketch

ZSketching a character

In this workflow, we can think of our ZSpheres as a skeleton we can place our virtual clay onto. So we try to build the armature, not as thick as the whole arm, but as thick as the underlying bone would be. With that in mind, let's get started.

ZBrush 4: Modeling a Creature with ZSketch

ZBrush 4: Modeling a Creature with ZSketch

Time for action – creating the basic armature with ZSpheres

Let's say the art director comes to your desk and shows you a concept of a monster to be created for the game project that you're working on. As always, there's little to no time for this task. Don't panic; just sketch it with ZSketch in no time. Let's see how this works:

  1. Pick a new ZSphere and align its rotation by holding Shift.
  2. Set your draw size down to 1.
  3. Activate Symmetry on the X-axis.
  4. The root ZSphere can't be deleted without deleting everything else, so the best place for this would be in the pelvis area.

    Placing the cursor on the line of symmetry will create a single ZSphere—this is indicated by the cursor turning green.

  5. Start out to create the armature or skeleton from the root ZSphere, commencing from the pelvis to the head, as shown in the next screenshot. Similar to the human spine, it roughly follows an S-curve:

    ZBrush 4: Modeling a Creature with ZSketch

  6. Continue by adding the shoulders. A little trick is to start the clavicle bone a bit lower at the spine, which gives a more natural motion in the shoulder area.
  7. Add the arms with the fingers as one ZSphere plus the thumbs, we'll refine it later. The arms should be lowered and bent so that we're able to judge the overall proportions better, as the next image shows:

    ZBrush 4: Modeling a Creature with ZSketch

    This "skeleton" will also be used for moving or posing our model, so we'll try to place ZSpheres where our virtual joints would be, for example, at the elbow joint.

  8. Add the hips, stretching out from the pelvis and continue with the legs. Try to bend the legs a bit (which looks more natural) as shown in the next screenshot.
  9. Finally, add the foot as one ZSphere for the creature to stand on:

  10. Now we have all the basic features of the armature ready. Let's check the concept again to get our character's proportions right. Because our character is more of a compact, bulky build, we have to shorten his legs and neck a bit.

    Make sure to check the perspective view, too. Inside any game engine, characters will be viewed in perspective. We can also set the focal angle under Draw FocalAngle|. The default value is 50. Switching perspective off helps comparing lengths.

  11. Add another ZSphere in the belly area to better control its mass, even if it looks embarrassing.
  12. To make him look less like Anubis, you may want to lower the top-most ZSphere a bit, so it will fit the horns. Our revised armature could now look like this with perspective enabled:

  13. With the overall proportions done, let's move on with details, starting with the toes. Insert another ZSphere next to the heels and continue by adding the toes, including the tiny fourth toe, as shown in the next screenshot:

    ZBrush 4: Modeling a Creature with ZSketch

  14. With larger ZSpheres, we can better judge the mass of the foot. But because we need a thinner bone-like structure, let's scale them down once we're done. Be careful to scale the ZSpheres, and not the Link spheres in-between them. This keeps them in place while scaling, as shown in the next image:

    ZBrush 4: Modeling a Creature with ZSketch

ZBrush 4 Sculpting for Games: Beginner's Guide Sculpt machines, environments, and creatures for your game development projects
Published: March 2011
eBook Price: $26.99
Book Price: $44.99
See more
Select your format and quantity:
        Read more about this book      

(For more resources on the subject, see here.)

  1. Let's continue with the hands. These can be tricky, even at this rough stage, so it may be useful to look at some reference images, either from anatomy books or the Internet. The next image shows some major lines that make up the hand. Starting the fingers in an outstretched pose is useful for getting the lengths correct:

    ZBrush 4: Modeling a Creature with ZSketch

  2. Add ZSpheres to the hand, following its bone structure, as shown in the next screenshot. It's easier to work out the length of the fingers first and then insert the joints afterward, as shown in the next image:

    ZBrush 4: Modeling a Creature with ZSketch

  3. Let's relax the expression of the hand by quickly rotating the Link spheres of the fingers, which is a better pose for animation. If you look at your own relaxed hand, you'll see that the main bending takes place between the first and second bone of your fingers. Also note that smaller fingers are bent more when relaxed, as shown in the next image:

    ZBrush 4: Modeling a Creature with ZSketch

    Rotating the Link spheres is done relative to the camera view, so make sure to adjust the view accordingly.

  4. Finally, we may want to scale down the wrist a bit so there's still room left to add muscles on top.
  5. Save the armature, as usual as a .ZTL.
  6. Our final armature could now look like this:

    ZBrush 4: Modeling a Creature with ZSketch

What just happened?

We've just finished the armature of our creature. We can now use it to freely sketch muscles on top of it with ZSketch.

We also covered some basic anatomy, such as the form of the spine or the lines of the hand. If you're interested in anatomy, there are plenty of good books available, for example, Die Gestalt des Menschen by Gottfried Bammes, which is available only in German but the numerous illustrations speak for themselves. Also searching through the Internet can be a good starting point. Personally, I would choose artistic anatomy illustrations over medical ones because they also deal with the visual appeal, which applies to sculpture, too.

As we'll see on the next pages, the armature we built will now be used to sketch muscles on top. So when using ZSpheres, we can choose if we want to build volumes directly from them, like we did with the tree, or use them as a skeleton for sketching volumes on top.

The character pose for animation

For characters in games, we always have to consider the next steps, which will be rigging and animation. Rigging is about placing bones and joints, determining how the character can move, whereas animation will finally move the character. Most of the time, a relaxed pose is better for the rigging process than the T-pose, with arms stretched out horizontally. The reason for this is that the model will deform better when it is modeled in-between its motion extremes. For example, an outstretched arm is an extreme for the elbow joint, so bending or relaxing it (like we did), solves this. The same applies for the fingers and the legs. Also lowering the arms makes sense, as most of the time, characters do have their arms lowered, not above their heads.

From an artistic point of view, the relaxed pose is also well-suited for judging the overall expression and proportions of the character

Enough of that theory, let's move on with the most enjoyable part—ZSketching the creature.

ZSketch hotkey reference
To increase our working speed, let's get an overview of some hotkeys for ZSketching. Luckily, ZSketching is done with almost the same controls that we already know from ZSpheres and sculpting:

  • Press Shift + A to enter sketch mode.
  • Left-click to draw.
  • Hold Shift to smooth.
  • Hold Alt to inverse the direction of the brush. When using Sketch brushes, holding Alt deletes the drawn strokes.

Like with ZSpheres, we can preview a unified skin of our ZSketch by pressing A. Pressing A again will leave the preview mode.
Hold down Ctrl + Shift + drag to hide parts outside the rectangle.
Drag the rectangle, but before letting go, press the Alt key to hide all of the parts inside the rectangle.
Ctrl + Shift + left-click on the canvas will unhide everything.
When working on one part of the model, don't hide the mirrored part of it otherwise you may get errors on the mirrored side. So when working with symmetry on the left arm, have the right one visible, too. For that reason, with symmetry turned on, all hiding actions are symmetrical.

Time for action – sketching the creature with ZSketch

Let's explore how easy it is to create characters with ZSketch. For me, this is one of the best features of ZBrush because it brings modeling closer to what sketching is—quick and intuitive. Let's see how this works by sketching out the creature's body.

  1. Open or select the previously built armature.
  2. Go to Tool ZSketch| and press the EditSketch button or hit Shift + A. Now we're in Sketch mode where we can sketch freely upon our armature.
  3. Make sure that Symmetry is active.
  4. Pick a material that starts with Sketch, which were especially designed to enhance the display of ZSketches. I'm using SketchShaded4 here.
  5. ZBrush automatically switches to the Sketch1 brush when working with ZSpheres so we can start right away. The next image shows how we can lay strokes onto our armature and smoothen them afterwards to blend into the existing sketch or armature:

    ZBrush 4: Modeling a Creature with ZSketch

  6. As shown in the third step of the previous screenshot, the Smooth1 brush scales the strokes to blend into the underlying surface.
  7. Begin laying strokes onto the model and smoothing them, starting with the form of the ribcage and the pectoral muscles, as shown in the following image:

    ZBrush 4: Modeling a Creature with ZSketch

    Have a look at the hotkey reference at the beginning of this section to speed up your workflow.

  8. Add the belly by using a larger brush as shown in the following image:

    ZBrush 4: Modeling a Creature with ZSketch

    Visual aids for ZSketch
    Like polygons, we can colorize our sketch by navigating to Tool Polypaint | Colorize| and picking a color. Turning off Zadd will colorize only—which is done in the next screenshot to better distinguish the sketch from the armature.

  9. Continue with the sides and the back. For a living creature like this, the ZSketch follows the flow of the muscles. Larger muscles can be represented by larger strokes and smaller ones by smaller strokes. Unless you're absolutely familiar with anatomy, looking at reference images will improve your sketch.

    ZBrush 4: Modeling a Creature with ZSketch

  10. Now that we've established the mass of the body, let's continue with the neck. Start by adding a bigger sphere where the skull would be. Like real anatomy, we'll then draw the muscles that connect the bones at the neck.
  11. Rough in the mass of the head with a few strokes.
  12. For the horns on the head, pick the armature brush, which starts on the sketch and then freely extends into space. Like rotating, the direction it extends from the surface depends on the camera view. Because the horns are somewhat horizontal, drawing them from the top will be suited best for this.
  13. Viewed from the side, the horns still need some correction. We can switch to the Move tool, by clicking on Move at the top of the shelf or by simply pressing W. Now we can push them into place as shown in the next image. With the Scaling tool, we can shrink the tips of the horns:

    ZBrush 4: Modeling a Creature with ZSketch

    Although ZSketching relies on ZSpheres, they are not using hierarchies, so we can layer strokes in any order we want.

  14. Adding some arms completes the torso area. Click on the icon of the Sketch1 brush and select the Smooth 4 brush from the list. ZBrush will then display a message telling us that we have to press Shift to switch to the newly selected Smooth 4 instead of Smooth 1, like before. The next image shows the difference between both:

    ZBrush 4: Modeling a Creature with ZSketch

  15. The Smooth 4 brush is really useful for muscle structures because it shrinks both ends of the sketch stroke. Use it to quickly add the muscles of the upper- and lower- arm, as shown in the next image:

    ZBrush 4: Modeling a Creature with ZSketch

ZBrush 4 Sculpting for Games: Beginner's Guide Sculpt machines, environments, and creatures for your game development projects
Published: March 2011
eBook Price: $26.99
Book Price: $44.99
See more
Select your format and quantity:
        Read more about this book      

(For more resources on the subject, see here.)

  1. Now that the torso is done, let's step back again and check the proportions. At the moment he looks more like an athlete, but lacks the body mass the concept has. Let's correct the proportions with the Move tool, as shown in the next image. We'll come back later to finish the hands.

    ZBrush 4: Modeling a Creature with ZSketch

  2. Let's continue with the legs. Its muscles are quite raised, so we'll switch over to the Sketch 2 brush, which draws a more elevated stroke on the surface. We can think of muscles as fabric made of thick, intertwining threads. Looking closely at reference images helps to see which muscles overlap others. Work out the legs as shown in the next image:

  3. The Bulge brush bloats surfaces, which is very useful for the dominant muscles of the leg, as shown in the previous image. We can press Alt to shrink.
  4. Save your work regularly with ascending numbers, so you can always go back if something goes wrong.
  5. The last thing our creature needs for a fresh walk in the woods is some feet. They can be roughed in quite quickly with some thicker strokes on the main foot and thinner tendons on top of that, as the next image shows. For the toes, the Smooth 1 brush is very useful because it adapts the stroke size to the small armature underneath:

  6. There's only one thing left to do now—the hands. Let's spread the fingers beforehand, so the ZSketch strokes won't jump over to the neighboring ones. Leave sketch mode by pressing Shift + A.
  7. Spread the fingers by using Rotate and enter sketch mode again.

    To get a better overview, we can hide parts, for example, the feet when working on the hands. But we should always have the mirrored parts visible, too—for example, having both hands visible when working on them. Otherwise, we may get errors when ZBrush tries to mirror things over onto invisible parts.

  8. For the fingers, start by adding some flesh onto the bones, followed by the joints and tendons, as shown in the next image. What looks like earthworms at the moment will be a good base to start sculpting from:

  9. Now that we have laid in all the muscles, we can use our previously built armature to correct some of the proportions if we'd like to. Leave sketch mode with Shift + A.
  10. Now go to Tool ZSketch| and press the ShowSketch button to view the transparent sketch and the armature at once.
  11. Increase the SoftBind slider to 100 and go to Tool ZSketch | Bind|; this allows us to adjust the armature while the sketch smoothly follows, which is neat. Now we see what that embarrassing belly control was made for. Bound to the belly control, we can move or scale the belly without affecting the back.

    If we change the structure of the armature, we can simply go to Tool | ZSketch and press the Reset Binding button and let ZBrush update the connections between the armature and the sketch. Add, move, or scale ZSpheres as you wish to get the results you want.

  12. Save your work.
  13. If the character should be able to open and close his mouth in the game, we should add a jaw with the mouth slightly open.
  14. After some reshaping with the help of our armature, the final sketch could look like this:

What just happened?

With ZSketching, we just enjoyed the freedom of free-form sculpting a complete character without having to think about polygons, resolutions, or vertex densities.

Brushes

We started out with the sketch brushes, layering strokes on the armature. As we saw, there are three different sketch brushes—Sketch 1, -2, and -3. Strokes with the Sketch 1 brush stay close to the surface, whereas strokes with the Sketch 3 brush will be elevated from the surface. The proximity of the stroke to the surface is controlled by the Brush Depth | Imbed| value, so all the three brushes are just presets.

The Armature brush does not follow the surface but rather starts off from it. Opposed to that, the sketch brushes will follow the surface as long as we paint on it. If we leave the surface at its borders, the sketch brushes will also lift from the surface, but they can join in again. So, use the armature brush for things such as tentacles or horns, and the sketch brushes for surfaces or for connecting those.

We get the best results if we combine our sketch brushes with the smooth brushes to blend into the surface.

ZSketch and the armature

With an armature, we do have a good starting point for modeling our character. But ZSketching is also about modeling freely, right? All we have to do is pick a ZSphere and freely sketch away without any armature or predefined outcome. We can still build an armature afterward if we want to.

Opposed to normal ZSpheres, ZSketching is not hierarchy-based, so we can sketch freely without having to follow any structure. ZSketching is sometimes also called ZSpheres 2 to emphasize that difference.

If the ZSketch becomes very complex and you get performance issues, you can go to Tool ZSketch| and press the Optimize button—this deletes unnecessary ZSpheres that are fully covered by others.

If we hit the A key, we'll get a preview of our ZSketch converted to polygons. The standard resolution for this is pretty low to avoid long computation times. But if we would like to see a more detailed preview, we can set the resolution under Tool Unified Skin | Resolution|. There's also a Preview button, which is what the hotkey A toggles.

Finally, we used our previously built armature to reshape our model. This is very useful for checking movement limits, too. This early stage is perfect to identify issues because they can be fixed so quickly. For example, a character may not lift his arms as he's supposed to because his head is too big. Changing this at a later stage will be much more difficult.

When entering Sketch mode, the brush selection will immediately switch to sketching brushes. If we want to edit our model with the sculpting brushes, we have to convert our sketch to polygons first, which will be the next step. Because this is not undoable, we use the ZSketch to lay in the main proportions and then sculpt in the fine detail.

Time for action – converting a ZSketch into sculptable polygons

Now we've got our sketch finished and would like to sculpt more details. So we have to convert it to polygons. Let's try that out:

  1. Load the ZSketch of the creature.
  2. Open the Tool Unified Skin| subpalette.
  3. The following settings worked best for me. If your creature looks way different, experiment with the values to see what works best for you:

  4. When testing which resolution will do best, pay close attention to small details such as fingers, toes, and horns, which tend to get lost on lower resolutions. Try to get the lowest resolution possible. Spreading the fingers even more may prevent them from being merged.
  5. Deactivate Symmetry.
  6. Press Make Unified Skin, which adds it as a new tool with the Skin_ prefix to the Tool list.
  7. Save both the tools—the armature and the newly created skin.

What just happened?

We just created a polygonal mesh from our ZSketch, we can now sculpt on.

The reason we tried to get the lowest resolution possible is that it's good to have lower subdivision levels for more global changes.

The preceding example will create a mesh with a resolution setting of 256. On top of that, it will generate two additional subdivision levels that capture the finer details. So when pressing Make Unified Skin, we should end up with a model with three levels of subdivision.

If we applied colored sketch strokes to our model, the Unified Skin will be colored, too. This can be a great base to start texturing from.

Disabling Symmetry before creating a Unified Skin creates more quads instead of triangles along the axis of symmetry. The difference may be marginal, but we should go for quads instead of triangles whenever we can.

Summary

We learned a lot in this article about ZSketching models within ZBrush and how to tackle all sorts of tasks that arise while creating a complete character from scratch. Specifically, we've covered:

  • A new way of creating models with ZSketch
  • Building up volumes and muscles can be quickly achieved with the various sketch and smooth brushes
  • For ZSketching, we can start off with a complete armature or a single ZSphere
  • Building some sort of skeleton with an armature is useful if we know where we're heading with the character
  • We can use that skeleton to control the ZSketch by binding it—like a skeleton with muscles on top
  • If we make global changes to the model, such as adding a tail, we can edit or insert its skeleton later in the process, too
  • Thinking ahead about the future movement of the character saves a lot of headaches when it comes to rigging and animation
  • To create volumes, ZSketching is unmatched in speed and fun, but when it comes to fleshing out finer details, the sculpting tools are the way to go
  • When switching from ZSketching to sculpting, we have to convert our sketch into polygons first

Further resources on this subject:


About the Author :


Manuel Scherer

Manuel Scherer is a German game developer who has worked in the games industry and in the fields of visual computing. He is currently teaching real-time visualizations at the Offenbach Academy of Art and Design.

Apart from his beloved work, he writes as a freelance journalist about the games industry from major events such as the Game Developers Conference Europe.

Books From Packt


Unity 3D Game Development by Example Beginner's Guide
Unity 3D Game Development by Example Beginner's Guide

Panda3D 1.6 Game Engine Beginner's Guide
Panda3D 1.6 Game Engine Beginner's Guide

XNA 4.0 Game Development by Example: Beginner's Guide
XNA 4.0 Game Development by Example: Beginner's Guide

Facebook Graph API Development with Flash
Facebook Graph API Development with Flash

Away3D 3.6 Cookbook
Away3D 3.6 Cookbook

OGRE 3D 1.7 Beginner's Guide
OGRE 3D 1.7 Beginner's Guide

Cocos2d for iPhone 0.99 Beginner's Guide
Cocos2d for iPhone 0.99 Beginner's Guide

Flash 10 Multiplayer Game Essentials
Flash 10 Multiplayer Game Essentials


No votes yet

Post new comment

CAPTCHA
This question is for testing whether you are a human visitor and to prevent automated spam submissions.
M
n
m
A
z
A
Enter the code without spaces and pay attention to upper/lower case.
Code Download and Errata
Packt Anytime, Anywhere
Register Books
Print Upgrades
eBook Downloads
Video Support
Contact Us
Awards Voting Nominations Previous Winners
Judges Open Source CMS Hall Of Fame CMS Most Promising Open Source Project Open Source E-Commerce Applications Open Source JavaScript Library Open Source Graphics Software
Resources
Open Source CMS Hall Of Fame CMS Most Promising Open Source Project Open Source E-Commerce Applications Open Source JavaScript Library Open Source Graphics Software