28 May ZBrush Tutorial: Master hair and fur
This ZBrush tutorial was written by the amazing Pablo Muñoz Gómez and appeared in issue 104 of 3D Artist
Learn how to use PolyPaint and groom and optimise fur
With each step of the following ZBrush tutorial, we’ll take a look at the various processes involved in the creation of the Alpha wolf illustration. The approach will be methodical and we’ll try to sculpt the 3D elements with the end goal in mind, to save time and optimise resources.
The creation process will start with the understanding of a few key points of the wolf’s anatomy, so that we can exaggerate them in order to make the illustration more interesting. There are a few important elements in the composition such as the pose, expression and camera position. We’ll try to keep these key elements in mind during the sculpting and grooming stages, so that each part contributes to the final image.
The majority of this tutorial will be done in ZBrush, but we’ll use Photoshop for compositing the various render passes. FiberMesh is an essential feature for the creation of the wolf’s fur, so we’ll spend some extra time during this stage of the process in order to get it right.
ZBrush Tutorial Step 01 – Identify the wolf’s features
ZBrush Tutorial Step 02 – Prepare the base mesh
When playing with proportions, there is a lot you can do without adding more geometry. In the previous step, the cartoonish version of the wolf has the same topology as the generic Dog.ZTL. It resulted from moving and smoothing areas. Similarly, you can create a precise base mesh that describes the volumes of your wolf. You can gradually start subdividing the geometry later, when more details are required. In this case, we are taking the existing topology of the Dog.ZTL and using the Move brush and Transpose line with masks to alter the proportions and shape the model like a wolf. Don’t worry too much about the polygon distribution, as this isn’t the final base mesh.
ZBrush Tutorial Step 03 – Sketch over the base mesh
As mentioned, you could have started with a precise base mesh and subdivided it as you need to add more details. However, in this case we’ll turn the current base into DynaMesh by enabling this feature from the Geometry palette. You can tweak the resolution slider to get more or fewer polygons to work with, and hold the Ctrl key and click+drag anywhere in the canvas to re-DynaMesh. With DynaMesh on, we can take the ClayBuildup brush and add some marks to establish a few anatomical anchor points. These will be helpful when sculpting the expression and other parts of the wolf’s body.
ZBrush Tutorial Step 04 – The key for the hair
We are still early in the sculpting process but this is where the foundations are laid. One of the most distinguishing aspects of wolves is the fur, and the intricate variations in its length and colour. We are going to fake these variations a bit, and sculpt some layers of fur with only geometry. This is a simple way to optimise the amount of fur for render time. You could insert a sphere and shape it, or use the geometry brush to create some planes over the model and then extrude them with ZModeler. In this case we are going to append a sphere from the SubTool palette so that each part of the ‘fur’ base mesh is a separate SubTool.
ZBrush Tutorial Step 05 – Refine the fur geometry layers
These additional SubTools, or pieces of geometry, are there to simulate the volume of the fur. They will also serve as a rough platform to groom the hair and pull it in a particular direction. A key aspect of making the plates of geometry useful is to integrate them with the main model, so that they follow a unified direction, and to ensure that the transition between pieces is not abrupt. A very cool trick is to use the SnakeHook brush, and hold the ‘Alt’ key while pulling an area. This will make the geometry you are pulling follow the adjacent geometry.
ZBrush Tutorial Step 06 – Sculpt the fur with geometry
At this point, we have a good foundation for the hair and the model is beginning to look more like a wolf. We can now go further and sculpt big chunks of fur in the geometry, like clumps of hair. This will give us an interesting look when grooming. We can make the fibres from FiberMesh grow perpendicular from the normals of the polygon. So, when groomed, these fibres will give us the effect of having more individual hairs under the surface, as the indentation will seem fuller. You can use the ClayBuildup and Smooth brushes to sculpt the chunks of hairs on the SubTools. The SnakeHook brush will help you achieve those long hairs transitioning between SubTools.
ZBrush Tutorial Step 07 – Retopologise
Once the sculpt is done, we’re going to create a cleaner topology and transfer the details.We can approach the retopology process in a few ways for this particular project:
• Leave all the current SubTools on and create a single mesh
for the entire model. We can split it up later and we’ll end up with a more fluid topology.
• Retopologise every single SubTool individually and have a bit more control over each part.
• Manually retopologise the most important parts and use a quick ZRemesher for everything else.
We’ll go for the third option as this will end up being an illustration and we won’t need to animate the wolf.
ZBrush Tutorial Step 08 – Use manual and automatic topology
Go ahead and append a ZSphere as a new SubTool and enable ‘Edit Topology’ from the Topology sub-palette. It is also a good idea to enable symmetry (‘X’ on your keyboard) before you start. This process might be lengthy and requires patience. Start drawing points along the head of the model to create a cleaner topology. For the rest of the body, we’ll use the ZRemesher under the Geometry sub-palette. You can play with the ‘Target Polygons Count’ slider if you need to adjust the number of polygons created in this process.
ZBrush Tutorial Step 09 – Transfer details
Now that we have a cleaner topology, we can transfer the details we sketched on our DynaMesh model into a subdivided version of the new model. Subdivide the newly created topology a couple of times, to have enough resolution to capture the details. Select the new mesh, make sure the sketched model is visible and click on the ‘Project All’ button under the SubTool palette. Once the details are projected, you can spend a couple of minutes cleaning up any imperfections resulting from this process and simply turning off the visibility of the sketch mesh (it is a good idea to keep a backup).
ZBrush Tutorial Step 10 – Cut up the model
Now we are going to split up the model to work faster and more efficiently (this is very important once we start working with the fur). Since we chose to create a SubTool for the head alone, we already have it as a separate piece. The rest of the body, however, is one single piece. The head will be a fundamental part of the final illustration, so grouping it, will give us much more control. It is also helpful to keep the body separate from the legs and tail but you can leave the rest of the body as a whole and polygroup the other areas after. You can use the Lasso selection tool to hide parts on of the model and use Ctrl+W to assign a polygroup. Or use the ‘Split hidden’ button from the SubTool palette to create a new SubTool.
ZBrush Tutorial Step 11 – Create UVs
Before creating the UVs, we’re going to create some more polygroups around the face. The idea is to create groups that allow you to quickly select certain groups of hairs for easy grooming. We’ll create polygroups for the ears, around the eyes, eylids, nose and jaw. Once we’re done with the polygroups, we can use the UV Master plugin to generate clean UVs for the model. For this particular tutorial, perfect UVs are not essential, but they let us transfer polypaint data to texture and save them as images.
ZBrush Tutorial Step 12 – Quickly texture
Now that we have UVs, we can add some colour to the wolf. The wolf in this tutorial will be a dark brown/black wolf, but painting the underlying geometry with more tones will make it look more interesting. We’ll cover everything with fur, so the texturing job doesn’t have to be precise. Import a few reference images from the Texture palette and add them to Lightbox. Using the Standard brush with only RGB enabled, roughly texture the model using your reference photos that match different parts of the body.
ZBrush Tutorial Step 13 – Choose a pose
Time to pose your model. Here is where you can give character to your wolf and add dynamism to your illustration. Wolves use a variety of complex non-vocal communications to express submission or dominance. To create tension, we’ll put the wolf in a threatening pose: teeth bared and lips curled, horizontal ears pointing outwards. The straight tail and lower head posture could signify hunting or intention to attack. To achieve all this, we can use Transpose Master to move all the parts into place. The Move Topological brush is also very helpful to fix tight areas.
ZBrush Tutorial Step 14 – Create fur
We need to create the fur after the model is posed, otherwise posing the wolf with fur would be an incredibly difficult job. We’ll create various groups of fur for the various sections of the wolf depending on the length. However, the process is the same for each part:
• Mask the area (and blur for smoother transitions).
• Preview FiberMesh, adjust if necessary and create fibres.
• Use the Move brush to move large areas into place.
• Use the Groom brushes to create the flow of the hairs.
• Use BPR to check progress, groom and move hairs further
ZBrush Tutorial Step 15 – Create fur transitions
Creating a natural transition between the different lengths and sections of the wolf is very important for a believable effect. The easiest way is to create three sets of fur per section that require transitioning: the short hair section, the long hair section, and the transition hair that bleeds into the short and long sections. We can use any of the grooming brushes to tweak and shape the fur. Since we also have polygroups, you can turn the Mask By Polygroups slider to 100 under the Auto Masking options of the brush to affect them individually.
ZBrush Tutorial Step 16 – Grow the fur
We’ll start with the head. With the head selected, turn on solo mode to work faster. Use the Masking brush to select the areas you want grow the fur (avoiding eyelids and inner mouth). From the FiberMesh palette, turn on ‘Preview’ and use the modifiers to tweak the look of your fibres. The trick here is to keep the MaxFibers slider low and compensate a bit with the Coverage slider. Use the PBR button to test the FiberMesh and click on Accept once you are happy with the result.
ZBrush Tutorial Step 17 – Groom the fur
Select the GroomHairShort brush to give direction to the hairs. It is a good idea to refer back to the photos you’ve collected throughout your planning stage to check the hair’s natural flow. Remember that the fibres are just polygons so you can use any of the sculpting brushes to tweak them. The Move brush is particularly handy to readjust the position of large areas of hair. Try to get the direction of the hair in one stroke. Going over the same area multiple times might twist the fibres and end up giving you some undesired rendering effects.
ZBrush Tutorial Step 18 – Grow long hairs
For the longer pieces of hair, we are going to create a more blurred mask on the mesh. This will help us with the transition from short to long fibres. You can play with the ‘ByMask’ modifier slider if you want to tweak the mask priority. Try to keep a low number in the ‘MaxFibers’ slider. The idea is that the sculpted chunks of hair will give us the structure and direction of the fur and we’ll only use FiberMesh to cover the ‘spike’ of geometry to complete the effect. If you find a few ‘bald’ spots after generating the fibres, you can cover them later with transition hairs using a very soft mask and low count of fibres.
ZBrush Tutorial Step 19 – Complete the final grooming and tweaks
At this point the hard work is almost finished. We can go over the areas with longer hairs and use a custom version of the GroomSpike brush in order to clump some hairs together. Expand the Brush palette and under the Twist options, change the Twist Rate and the Radius sliders to 0. You can also reduce the Z intensity a bit to have more control. With this custom brush you can pull some long hairs together, especially around the cheeks, neck and chest of the wolf. An additional trick is to use the GroomTurbulence brush with a very low Z intensity (say 5) and go over the entire model to give it a more natural ‘messy’ look.
ZBrush Tutorial Step 20 – Finish with BPR passes and compositing
Once you are happy with the wolf model (and the fur), you can choose a camera angle to start the rendering process. The most important step before you start your renders is to set the document size and save your camera angle (from Document> Zapplink properties). You can render as many passes as you need for the compositing but there are a few which are essential: a Colour or beauty pass, a Shadow pass, ZDepth, Alpha and any light passes. Other passes such as AO might be helpful but they’re not essential. Save the BPR passes as PSD files from the BPR Renderpass palette and drop them into Photoshop as individual layers. For this illustration a ground plane was quickly sculpted and added before rendering to make the compositing a bit easier. The background is a series of painted layers, blurred at different values to simulate the depth of field.
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