Six leading artists provide their tips for modelling ultra-realistic characters in ZBrush, Mudbox, modo and Silo.
When digital sculpting tools were first developed some ten years ago, they reinvented the way 3D modellers work. Instead of painstakingly patching NURBS curves or pulling vertices, the new tools mimicked those of the real world. Digital modellers became sculptors, and the new generation of packages incorporated brush-based modelling into their toolsets. CG sculpting has now become a standard in the pipelines of film and games studios across the globe.
With their intuitive design and more user-friendly layout, the latest generation of modelling software enables 3D artists to quickly get up to speed and start sculpting. Rather than focusing on the tools, modellers nowadays are freed to perfect their artistry. And that, of course, starts with a well-proportioned base model. For more on that subject, see 3D World issue 75, where Scott Eaton’s looks at the fundamentals of anatomy.
In this feature, six of the world’s best digital sculptors, from some of the leading film and games animation studios, share their expertise on the best ways of detail modelling lifelike, humanoid characters. As well as covering software-specific tips for ZBrush, Mudbox and Silo, we’ve also scooped a few pointers from Luxology’s director of training on the soon-to-be-released modo 301, which now includes brush-based sculpting.
Alongside our collection of useful techniques and handy shortcuts, we’ve included a 10-step sculpting guide that demystifies professional modelling workflow: from gathering your reference material to preparing your UVs, and finally to exporting your sculpt ready for detail modelling.
Whichever package you’re using, the most essential part of the modelling process is building life into your character. Read our tips, follow the suggested workflow, and before you know it, your character will be bounding off the screen.
[ZBRUSH] CREATING REALISTIC SKIN
Creating realistic skin is all about perfecting the surface detail. First alter the uniformity of the surface by drawing with random irregularity. Then use a custom alpha, containing lots of spots, to add skin pores. Additions like micro-scars can be added later. But don’t overdo it – you will only achieve realism through balancing detail and subtlety. [SL]
[GENERAL] TESTING YOUR TOPOLOGY WITH EXTREME POSES
Too many artists rush straight into detailing their models before they’ve tested their topology. By first testing a few extreme morph targets, you can ensure you’ve created a dense enough mesh to hold up even in the most extreme action. Or even better, model the face in an extreme position right from the beginning, then morph the final result into a neutral, relaxed pose. [ABo]
[MUDBOX] REPROJECTING DISPLACEMENT MAPS INTO A NEW TOPOLOGY
A good part of the modelling pipeline inevitably involves working and reworking character designs according to the director’s latest feedback. With Mudbox this workflow is non-destructive. Displacement details can be easily preserved and transferred to your new topology. First bake your displacement map from the old model by going to Utilities > Texture Baking, then use the resulting map to displace your new model. Import your current .obj, and select Mesh Displacement from the Utilities tab. Bingo! Your latest model now has the same detailing as the old, but with your latest topology. Details can be masked using the Layer Mask brush (since the Mesh Displacement process displaces your details into a separate layer), or you can plug a map right into the Mesh Displacement. [AB]
[ZBRUSH] CHECKING YOUR WORK IN THE SHOT CAMERA OF A 3D PACKAGE
Avoid relying on ZBrush’s default orthographic views when modelling, or you’ll inevitably find yourself correcting for surprises when viewing your final model through a true perspective camera. Although ZBrush has a hidden perspective camera found under the Draw menu, its perspective slider doesn’t represent a true camera lens. It’s far better to check and recheck your model through a true perspective view. Import your model back into your 3D package of choice at regular stages through your design process. Check your work through the shot camera, then re-import it back to your sculpting package to continue modelling. [ME]
[ZBRUSH] WORKING WITH REFERENCE CURVATURE WHEN MODELLING
As every character modeller knows, modelling eyelids to fit snugly over the eyeballs is very tricky without using reference curvature. Borrow a tip that sculptors have used for years when working with clay. Create a pair of perfect spheres in your 3D package, then merge them with your body sculpt before exporting to ZBrush. In the Tool menu select PolyGroups > AutoGroups. That creates separate polygroups for each eyeball and the skin. [Ctrl]+[Shift]- click on an eyeball sphere to hide everything apart from the eyeball. Then [Ctrl]-click in empty space to mask the eyeball, which will now turn dark grey. [Ctrl]+[Shift]-click again in empty space to restore the other hidden objects. You can now sculpt over the eyelids while pushing against the eyeballs for curvature reference. [ME]
[ZBRUSH] FAKING AN ERASER BRUSH
Are you missing that Eraser brush from Mudbox? Now you can mimic similar behaviour in ZBrush. Let’s say you have three layers, Base Layer, Muscles, and Pores, each of which has its own details. To erase some of the pores on the Pores layer first click off the layer’s visibility, eliminating all the pore detail. Next select Tool > Morph Target and click StoreMT. This stores the state of the vertices. Now that you have the morph target saved you will see the Morph brush become visible in the Brush palette. Click on the brush and switch your Pores layer back on by selecting the visibility icon. When you paint on your object with the Morph brush it will now act like an eraser. Don’t worry: this trick is a cheat that does not actually erase the data from the layer. [RD]
[ZBRUSH] USING MORPHS AND MASKS TO ISOLATE AREAS
Struggling with the best way of isolating your character’s bottom lip from his top lip, in order to allow individual precision sculpting? Then here’s an easy way to isolate areas as separate groups within ZBrush. First, store a morph target. The lips will probably be closed at this point. Now, use the Smooth brush to smooth the entire lip area. This averages the spacing of the vertices, and allows you to separately select the upper and lower lips. Once you’ve done this, mask out the upper lip area, while clicking [Ctrl], to smooth out the mask. With your mask in the Morph Target menu, click Switch. This brings your object back to its original place, smoothing it with the mask still selected. On the bottom of the Masking menu, select the HidePt button to hide all the masked polys. If you want to hide the unmasked polys, just inverse the mask with the Inverse button (also found in the Masking menu). Once you have those hidden, you can create polygroups on the basis of hidden faces. [RD]
[MUDBOX] PROVIDING ANIMATED DISPLACEMENT MAPS
Even with the densest mesh, you’ll often still be required to provide animated maps for complementary wrinkles (a frown, for instance, or raised brows). First, import your neutral face. On a separate layer import your morph target (for example, the frown). Add the wrinkles or other detailing on the morph target layer. Test how the model morphs by sliding the layer’s Transparency slider. Once you’re happy, bake the map. This handy tip is useful not only for obvious areas like wrinkles in the forehead, but wrinkling on the elbows when an arm is stretched, or on the wrist when the hand bends back. These are the kinds of subtle nuances vital to sell the most realistic models. [ABo]
[ZBRUSH] POLYPAINTING WHILE VIEWING CUSTOM MATCAP MATERIALS
Although this isn’t strictly a sculpting tip, it’s very useful for visualisation during your modelling process, and overcomes ZBrush’s problems using custom non-white MatCap materials whilst PolyPainting. You might have already noticed that the colour you paint doesn’t show up correctly on your model. What’s happening is the paint colour is getting added into the colour of the MatCap material. Let’s say you have a skin shader that by default is a skin colour with a little bit of a red falloff. First, you need to tell ZBrush the base skin colour is the actual base colour that you want to start painting with. You then need to tell ZBrush that the base colour isn’t white by selecting the hue you really want. Typically, this would be the colour that is showing up in the viewport at the mid-value of your object. Colour-pick the shaded viewport by clicking [Alt]+[C] to bring up the Color palette, then click and drag on the foreground colour swatch located in the upper right-hand corner. While still holding down the mouse, drag onto any area of the model that represents the mid-value colour. Don’t click any highlighted or recessed areas. While still dragging, hold down the [Alt] key. The colour swatch will reflect what’s shown on screen. Once you have your mid value, click on the FillObject button (also located in the Color palette). Open the Material palette and expand the Modifier tab. Right above the picture, you’ll see two little spheres and four white boxes. The first white box is called Base. This is the colour that ZBrush thinks is the base colour for the material. Click on the white box called Base, and the foreground colour that you just filled your object with becomes the base colour of your material. Your object should now reflect the colours you paint. [RD]
[SILO] FAKING A BLINN SHADER
Silo’s default shader is a Lambert shader – not the most useful tool when visualising detail modelling in the viewport. To fake the look of a Blinn shader, change the default setting of the Diffuse value in the Material Editor to RGB 126, 126, 126, the Specular value to RGB 213, 213, 213 and Shininess to 16. Leave the rest of the values at their default settings and you’ll have the look of a Blinn shader in the viewport. For Maya users the alternative is to import your Maya model with a Blinn shader already applied. Set that shader as default by right-clicking on the shader and selecting the option Set As Default. [MA]
[MODO] SCULPTING WITH IMAGE MAPS
Image-based sculpting in modo 301 lets you add fine detail by creating a vector displacement where detail is a function of image resolution, not poly count. If you’re working with vector displacement and you want to export the model to another application, simply freeze it at a high subdivision level to create a regular polygon object containing all your detail. You can also modify the base mesh directly using mesh sculpting to create a high-poly model, then bake out a displacement or normal map and apply it to a lower-resolution cage. [ABr]
STEP BY STEP
The stages of a professional sculpting workflow
1: Gather reference material. The more the better, and be imaginative! If you’re creating aged, wrinkled human skin, elephant or ostrich leather make great references.
2: Start drawing up concept designs, thinking about how you’ll convert your character’s main features into primitives following the proportions.
3: If your character requires complex topology, work out the loops on your drawings. Study alternatives for facial deformations where you might need three edges or more for a wrinkle.
4: Get rolling! In Maya, or your 3D software of choice, start sculpting the character as a simple whole. Focus on overall proportions and don’t get bogged down in details.
5: Clean up your topology. Take into consideration areas with underlying muscle deformations when reworking the density of your mesh.
6: Once the topology is looking good, unwrap your UVs. At this stage it is much faster and easier to extract them non-stretched.
7: Time to turn to detail modelling. Still within your general 3D package, isolate then hide different areas of the model to focus on them individually.
8: Give the whole model another refinement pass. Unhide everything and perform a quick ‘sketchy’ sculpt to help you focus on rhythm and proportions.
9: Perform an extra relaxation or unfold (if you’re using Maya) on the UVs for your refined UV pass. Ask the texture painters and TDs whether they have any specific UV requirements for paint and shading
10: Test your topology through muscle deformations and blend shapes, then export it to your favourite sculpting software. Now the fun starts!
THE EXPERTS
MOHAMMED ANUZ
Senior character artist at Pixion in India, our Silo expert, Mohammed, has also worked at Rhythm & Hues and Acony Games
http://mdanuz.blogspot.com
ALESSANDRO BONORA
Framestore CFC’s ZBrush and Silo expert, Alessandro is currently working on The Golden Compass and The Dark Knight
www.framestore-cfc.com
ANDY BROWN
Training director at Luxology, modo artist Andy has helped thousands of people learn to build watches, guns and cars
www.luxology.com
RICH DIAMANT
With credits including Guild Wars and Fight Club, Rich is also a specialist in ZBrush, and lead character artist at Naughty Dog
www.rd3d.com
MATT ESTELA
Co-director of London animation studio and school House of Curves, Matt is a well-known Soho freelancer and ZBrush pro
www.thehouseofcurves.com
SEBASTIEN LEGRAIN
Senior character modeller at Ubisoft, Sebastien knows his way around ZBrush. His credits include Rainbow Six Vegas
http://sebleg.free.fr
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