Hair creation with XGen
Welcome to this step-by-step guide where I'm going to show you the process that I used to create the hair for my latest personal project, Magni, King of the Ironforge. I hope this article helps you get more confident when it comes to hair creation for characters, and also encourages you to apply the information that you are about to see below in your own characters.
Setting your project inside of Maya
One of the biggest mistakes people used to do when start with XGen is to not set the project before starting the grooming. This is a very simple step and it is the first thing you have to. I personally like to go into Project Window, this way I will have a very organized folder setup for my entire project. If you have problems with the destination go to the Set Project window in file, and set the project destination to the root of the folders that were created.
Organizing your geometry
Before we start the hair creation, we need to organize our geometry to have a proper groom. My personal approach is to work with detached geometry to grow the hair, so I simply select the faces of my model where I want the hair to grow from and detach it, rename it, and put it on a group where I can identify it as the XGen geos.
Another important step is to have proper UVs on the geometry that you have detached – this is crucial to paint control maps later. Make sure to organize your UVs in the first UV island, I'm not completely sure about that but I don’t think XGen recognizes UDIMs.
Select the detached geometry and go to Generate > Create Description, name your description and collection properly, make sure to check Randomly Across The Surface and placing and shaping guides, then hit Create.
In order to style the hair the way we want, we need to create some guides across the surface. These guides will tell the hair what direction he needs to follow. Make sure to give enough space between each guide that you place on the surface. Another thing to keep in mind is to brush the guides in a way to make volume, when the hair is created it will interpolate between each guide.
In most of the cases we want the hair to grow in a specific area – to do that we use some control maps to help us. In this case I'll use a density map to exclude the borders of my scalp; this will make the transition of the hair look more natural. The areas in black specify where the hair will not grow and the areas in white where the hair will grow.
After I'm satisfied with the guide work I made, I start to play with the modifiers. One of the most important modifiers you will have is the clump. I usually work with 2 or 3 levels of clump, the first one will be sort of like a broad effect clump and then I start to create other levels a bit tighter, with different clumping maps.
Another important modifier is the noise; this will give a more natural look to the hair. Just like the clump, I use the noise modifier in levels, from big noise levels to small ones.
For the braids I used an insert mesh brush from the BadKing website that already has a nice topology. I brought it into Maya and created Splines from the existing topology. After that I aligned the tips of the spline in a base geo and used a utility modifier from XGen called "Curves to Guides", this way the splines created from the braid geo becomes XGen Guides, them I repeat the steps the we talked up here, paint density maps and create modifiers.
Creating nice-looking digital hair takes time and is a back-and-forth process; this means sometimes you will have to re-work your guides, take a step back, and re-paint your maps, modifiers, and so on. It is a very complex process, that's why we have professionals dedicated only to grooming in the VFX industry.
I really hope you find this article useful. If you want to dive more into grooming I highly recommend you check Jesus Fernandez’s content, he has some free videos on YouTube covering the very basics of XGen, and also a Patreon page with more advanced subjects.