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This chapter we will dive into sculpting our high poly mesh in ZBrush. In our previous parts, we created a base mesh in ZBrush and then took it into 3ds Max/Maya/LightWave/modo to be remodelled (Fig.01). The emphasis was on good edge flow, topology, and animatability. This will really help us out during the sculpting phase. Bad topology, uneven polygons, and poor construction can make our job very difficult during the sculpting phase, creating pinches and overly dense areas of mesh. Think of a wood sculptor. Wood has a certain grain to it, and there is a noticeable difference between sculpting against the grain and carving along with it. In the same way, if our topology roughly follows our musculature it makes it a lot easier to produce a clean model.
We are going to start by opening our base mesh in ZBrush, so go ahead and export it from 3ds Max/Maya/LightWave/modo using the Obj exporter on default settings.
Note for 3ds Max users:
There are a number of settings added to the 3ds Max exporter in Max 2008, which can complicate things somewhat and can be confusing. The default settings work well for any version previous to this, but if you are running 2008+ then choose the Maya option from the dropdown list of presets. If ZBrush or Mudbox is selected, the model seems to change and has a different vertex order. This is not a problem for this initial export, but later when we want to subtly adjust our base level model and re-import it, ZBrush will refuse a model with a different vertex order, even if the poly count is the same.*
Note for Maya users:
You will need to enable your Obj exporting options, if you haven't done so already, by going to Window > Preferences > Plugin Manager > Objexport, and check Load/Auto Load. Once this is loaded, exporting is fairly straightforward. Click either of the Export (Options) boxes under File, and make sure that all of the options are checked on.
Note for LightWave users:
LightWave is much simpler than other packages in the sense that it doesn't have any vertex re-ordering export settings; it's simply just an Export OBJ option.
Note for modo users:
We are going to start by opening our base mesh in ZBrush, so from modo's top File menu, select Save As or Export As, and select Wavefront OBJ (.obj) from the drop down list. Then click Save when the Confirmation request comes up.
In ZBrush, click on the Tool > Import button, and navigate to where your saved base mesh is located. The model will not appear on the canvas yet, as we have just imported it into the Tool palette. We now need to drag and release the model onto the canvas and make it editable (shortcut key Q). The next step is to open the Tool > Geometry palette, and click on Divide a few times. I have chosen to divide the model 4 times and would advise 3 or 4 divisions as optimal. Too high a division and it can be problematic when moving large areas around, too low and we don't have enough polygons to start blocking out our anatomy.
When there are too many divisions initially, adding detail too early becomes very tempting. Detail should ideally be left to the last pass once the forms and anatomy are perfected. Again, it's useful to think of it as a wood carving. If you add detail to the carving early on you commit yourself to the forms and shapes of the sculpture at that point in time. This is very limiting and leads to models looking visibly inaccurate. Of course, this is digital work, thus we have a lot more freedom to modify our model even after detail is applied, but the same principles apply and are useful to an optimum workflow. Getting caught up in detail is a beginner mistake, but one that with a little patience can be overcome and better results can therefore be produced.
We need to make sure our camera is in perspective view, by clicking the Persp button inside of the Draw menu. You can adjust this number to around 45 for an optimal field of view, but feel free to modify it to something that feels comfortable. Just be aware that the lower the number the less perspective your model will have, and sculpting without perspective can lead to creating a model that looks very different once we take it into our 3D application later, or render it.
Now our model is divided, we should import two spheres to be used as eyeballs. You can skip this step, but I find that it is a huge benefit to actually have spheres in the eye sockets, so we can sculpt the eyelids around the spheres without so much guesswork. Open up 3ds Max/Maya/LightWave/modo and open your last base mesh scene. Create a sphere in one of the eye sockets and place it correctly. For a human, the width of the temple should be about five eye widths wide. I estimate this character would have five-and-a-half to six eye widths. Make sure to compensate for the effect smoothing will have on the eyeballs, as it will shrink them somewhat. It's useful to apply a Turbosmooth now and scale the eyeballs to fit the sockets. Now we apply a symmetry modifier to the eyeball mesh, and set the axes to 0, 0, 0. Export this mesh as an Obj using the same export settings as before.
Back in ZBrush, click on the ZSphere icon in the Tool palette. This switches the active tool to a neutral one and we are ready to import our created eyes model. Again click Tool > Import and choose the newly exported eye Obj. Look over to the Tool palette. You will see a bunch of models, of which one of them will be the divided base mesh model we are sculpting with. Click that one and the model will appear again on your canvas, editable. The models don't disappear once you switch tools, they simply get stored inside of the tool palette ready for later use.
Expand the Tools > Subtools palette and look for the Append button. Think of a model in ZBrush - a ZTL - as a group. That group is split into several models, each being a SubTool of the main tool. We can edit each of these SubTools individually, in place. We will append in our eye model as a SubTool by clicking the Append button and then clicking the eye mesh that should be near the top of the popup window. The eyes then are added to the tool and we can select, move and edit them as we wish.
This would be a good time to start creating some custom brushes in ZBrush, you can do this by opening the brush menu and docking it to the side toolbar by pressing the little circle in the top left of the menu. Alter the settings here of a particular brush, give it a name, and if you like an icon. Then save it. Good settings to modify are Gravity, which drags the geometry down as you sculpt (this is great for cloth), and BrushMod, which pinches the geometry together as you sculpt (this is great for wrinkles).
Since I've already worked out the silhouette of my model, there is not much remodelling to do in regards to the shape and proportions. I can go directly to blocking out the muscle groups that will be most prominent in the model. The interesting thing about modelling for games is that we have to be aware of the distance at which the model will be viewed. If the game is a first person shooter you may view the characters up very close, whereas a third person game you may never see the character close enough to see skin pores or small scars. This kind of consideration can affect how we model the character and how we paint our textures. I'm going to decide that this is a character for a role-playing fantasy game, and therefore will be viewed both from a distance and up close. It's therefore important to have enough detail in the face to withstand close-ups, and have muscles still pop out to maintain the character's personality and look from a distance.
A good way to quickly block out forms is with the masking tool. Choose a brush like Standard or Clay and hold down Ctrl. Then simply paint the areas of indentation onto the model's neck (Fig.02).
Invert the mask by holding down Ctrl and clicking in an area of space outside of the model (Fig.03).
Switch to the Move brush and pull the area that is unmasked inwards. Now we have a quick and dirty neck sculpted. We can then unmask by holding down Ctrl and dragging and releasing in an area of space (Fig.04).
Smooth the model by holding down Shift and, with a Standard brush, painting over our neck. Go on then to work the forms of the neck more, using a combination of the Clay and Standard brushes to bring out the neck muscles. As this is a strong, muscular character, the neck muscles will be very pronounced. Remember this masking technique throughout the process, as it can be applied to numerous areas. Any muscle groups can be painted and inflated; areas between toes and fingers can be quickly pulled in or out and fingernails can be created using masking, as well as many others.
Moving onto the chest now, I'm using the Clay Tubes brush to outline the pectoral muscles. The Clay Tubes brush is my personal favourite brush to use at this stage of a character. It quickly adds layers of extruded geometry in the same way one could apply layers of clay and then smooth it with your thumb or a tool (Fig.05a - 05b).