How to Auto Rig Cyborgs With Character Creator AccuRIG

Digital Artist José Tijerín has shared a detailed breakdown explaining how to utilize Character Creator's new AccuRIG tool to auto-rig soft, rigid, and mixed armor pieces.

CC4 With AccuRIG: A Gateway to New Possibilities

AccuRIG in Character Creator 4 is the most important tool we’ll be using for this tutorial. This tool is designed to rig characters quickly and easily and lets us skip a lot of manual processing in 3D programs like Maya. To create this tutorial, I have divided the character into three categories: rigid armor, mixed structure, and rigid system. This makes it easy to understand and analyze the common mistakes for each category.

Part I: The Rigid Armor

Let’s explore several ways to correctly integrate different parts to make a suit of armor. For this tutorial, I’ll be working with the “Polish Hussar Armor” that can be found on the Tijerin Art Studio Sketchfab page. Let’s start with the simple minor parts of the armor, such as the tassets and vambraces.

First go to the Create to access the Accessories menu and import these armor parts. Since the armor is divided into parts, we will have to select them one by one to convert them into accessories using the namesake button. Now, we have to go to the lower part of the Modify window to find the Attach section and link the armor parts with their corresponding bones. This method is the most optimal for attaching rigid parts to the character, but it is not always recommended. I suggest individually importing the armor parts so that each part can be given the necessary attention and independent problems can be corrected as they arise.

Thanks to the improvements in Character Creator, we can check for problems while the character moves without having to leave the program. There will be times when the armor pieces intersect with other models and in those instances you will need to edit the geometries right away so it doesn’t continue to happen. Rigid elements, like the ones applied here, are widely used to complement cloth and leather clothing and give a striking touch of variety to our character. Let’s talk about the armor elements that are more complicated, so much so that they require rigging such as the helmet for this particular character.

Helmet armor

Helmets are usually composed of one or two pieces, but this particular helmet has several pieces at the back. This is an opportunity to take advantage of because the lower part collides with the armor that we have not yet placed. We can handle this problem by rigging this part in a third-party 3D application. This time, we are going to import it not as an accessory but as a 3D prop so that we can introduce the bone system without a hitch. The rest of the process is the same as those used for previous armor parts. As you can see, we now have full control over the helmet and can prevent it from intercepting other armor pieces. We are going to further develop this solution for the animation phase so that it goes beyond just fixing problems and takes us a step further in the animation of the character.

Chest armor

Now is the time to place the chest armor, which presents a delicate challenge. In this case, we have a one-piece breastplate that will be placed in the same fashion as the first armor parts. This type of armor is very constrictive on the body, so we must refrain from animating the bones of the upper spine and raise the arms more than 180 degrees. The most popular method, due to its versatility, is to separate an upper part to protect the thorax and a lower part for the stomach.

Shoulder armor

For the shoulder pads, I attached the lower part of the arm in the same way I did the first parts of the armor. For the upper part, I added a couple of bones like I did for the helmet. The mobile parts of a traditional armor are usually joined together with leather straps, and normally, they are covered by metal. This armor, however, features straps that are visible and I’ll need to be careful to confine the flexible areas to the shoulders. It’s worth mentioning that futuristic armor found in video games often contain rigid parts that are sewn onto flexible parts. This type of design can save on polygons and eliminate many of the problems mentioned before, but we will explore this later.

By attaching the bones to the armor, we get several possibilities for animation. We can correct the position of the shoulder pads as was done for the helmet. In addition, we can have those pieces jump while he is riding on his mount. It should be obvious by now that adding bones to the armor requires some forethought, especially about the character’s range of motions and how the armor will react in kind.

Scabbard of the sword and accessories

Let’s now examine the scabbard, which is usually a prop for decoration, but we can do more with it by rigging it to make it functional. To accomplish this, I add bones along the length of the leather scabbard to have it curve with the sword. Once set up, the sword, despite its curvature, can smoothly slide in and out of the sheath.

In the act of sheathing a sword, one hand holds the scabbard and the other hand inserts the sword. So we should consider adding a bone to attach with the hand. If we want to get fancy, we can export the props in FBX format along with its animation into Character Creator. On top of this, we can also add a spring effect so that the soldier can sway while he walks and have that momentum transfer to the sword while it is sheathed. Once completed, I continue to make some corrections and add the rest of the armor, accessories, and textures to make it ready for animation in iClone.

Part II: Mixed Structure

In this tutorial, I’ll explore what I call a mixed structure for making a suit of armor with Reallusion’s toolset. This type of structure is very suitable for making robots and cyborgs because it has a more modern or even futuristic aesthetic. We’ll be using the “Neo Robot” character which comes with this exact system of mixing rigid and flexible structures. You can download this character from Sketchfab.

How to use AccuRIG in Character Creator 4.1

First, import the character directly into an empty project in Character Creator. If you haven’t done so already, proceed to rename all the parts of the robot to make it easier to work with later. After that, we can ready to use a new tool that Reallusion has added into Character Creator.

AccuRIG is a tool that has opened new horizons for Reallusion products. Now, Character Creator is no longer a program entirely focused on realistic or stylized characters, it can actually load all types of characters. With this improvement, Character Creator is no longer limited to certain types of projects and has become an essential tool for any project that involves 3D models.

I’m going to select some of the rigid components and click on the AccuRIG button on the right. In the AccuRIG menu, click on the Create Guides button. The system will proceed to place the joints in an arrangement that it deems best based on its algorithm.

But how can we confirm if these are the best positions for the joints and modify them to better fit our model? Character Creator makes this easy by displaying a small help window every time a joint is selected. The system is usually pretty good at placing the joints into correct positions.

When we have verified the joint positions, click on the Generate Skeleton button. This is where the magic happens. In other programs, creating and adjusting a skeleton would undoubtedly take hours of your time.

The skeleton that the Character Creator generates is perfectly adjusted to fit the character’s anatomy. Yet, we can still adjust some parts that we are not satisfied with and use the Bind Skin button. As you can see in this example, the results are fantastic. It is even perfect for the fingers which are usually prone to errors due to their close proximity with one another.

Even the rigid parts of the model deform so slightly that it is almost imperceptible. That’s why for cases like these, it’s better to leave the rigid pieces as parts of the model rather than separating them into individual pieces. 

Models with a lot of overlapping parts will likely encounter mesh penetration, but you can use the Skin Weights tool to quickly check the skinning. Another thing you have to take into account is that you can’t use the Transfer Skin Weights button to fix mistakes in your rigged characters, instead you will need to go back to the AccuRIG menu and use the Bind Skin button.

Animated add-ons in iClone 8

When dealing with robots in iClone, there is one factor that you should take into account, that is animated components. Electronic components are often tacked onto futuristic characters and they may even have their own motions.

Adding these elements is really easy in iClone. We simply need to import the pre-rigged components and position them in the right places. When they are all positioned, we have to use the Link option on the nearest bone of our character and we can animate this element independently without separating it from the body. Furthermore, we can explore the use of robotic extensions as part of the character’s body.

The classic example is the articulated arm that is fully animated. Creating this setup is much easier than you might think, thanks to AccuRIG. We can simply import the mechanical arms into Character Creator and press the AccuRIG button to start the rigging process, just like before. In this case, not all bones will be needed for this model, such as the leg bones. AccuRIG provides a practical solution to mask out these bones so that they don’t interfere with the rigging process. As mentioned a moment ago, we can just import the model into iClone and use the Link option to attach it to our character.

Part III: The Rigid System

The rigid system is one traditionally used for classic robots. It is the most complicated system because we cannot use elastic elements and deformations, forcing us to think very carefully about the structure that makes up the character.

Use of spheres in the joints

As you can see, the whole system is based on using spheres as joints, but we also have some hydraulic parts that will need to be integrated into the rig. 

Now check how well the sphere system works in Character Creator and let’s see just how useful it can be to incorporate the hydraulic tubes. These tubes have polygons at the top and bottom. In this way, the lower polygons can bind to the hips and the upper polygons can bind to the chest. When the character moves, it gives the impression of the hydraulic tubes sliding to smoothly expand and contract. This method was used in practical production for my upcoming video game The Evil Furry on Steam. 

In this version, I wanted the robot to be more friendly, so I added light bulbs on the sides of the spheres that can move independently. I also added two antennae with spring effects to make the head more dynamic.

Facial expressions on a deadpan robot

I also wanted this robot to possess facial expressions and the ability to talk, despite it being a rigid robot. It occurred to me that the way to do this is to use a base character in Character Creator with all the expressions and lip-sync systems already set up with what the program has to offer.

To have all these features, I needed to work off of the base character and add the rest of the armor as clothes. It is a slower process, but it’s worth it for all the animations and expressions that the face has to offer.

That is all! I hope you like the final result and that the tutorial has helped you.

José Tijerín, Digital Artist

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