There are many things that flow into the development of a successful rig for a 3D configurator. One of the most important is the correct skinning of the skeleton with the character or object. Without skinning, the mesh would not deform properly and no matter how big the rig setup is, if it is not skinned properly, the entire rig will suffer. In the following article we will show you the high relevance of skinning. We will also give you some helpful tips to help you skim your rigs more safely in your next project.
What is Skinning?
Skinning is the process of binding the actual 3D mesh to the joint setup you created. This means that the bindings you create affect the corners of your model and move them accordingly. The difficulty is that a rig typically consists of hundreds of individual bindings and most bindings only need to affect certain parts of the mesh. For example, the wrist joint of a figure should most likely only control that part of the model. Of course, if you move the wrist and this affects the character’s shoulder, it wouldn’t look right. This is where skinning comes in. Skinning is essential not only for creating a model that moves precisely in the right places, but also for correct deformation. If you are a Maya user, you probably know the Smooth Bind command. This actually binds the entire skeleton to the mesh by clicking a button. Of course things aren’t that easy and Smooth Bind is just the first step to skinning the skeleton on the 3D mesh. By default, Smooth Bind works by finding nodes closest to the joints and assigning the influence based on the distance. That’s all well and good, but the computer doesn’t do the best work, which means it’s up to you to do the job and assign the right influence manually once you’ve bound the mesh to the skeleton. Wouldn’t it be nice if the job could be done at the push of a button? Part of the skinning process is called weight painting, which you may know. Painting the weights is actually what allows you to determine the right influence that each connection has on your mesh and is an important part of the skinning process.
As mentioned earlier, if the skeleton is bound to the mesh, the computer does not know exactly how much influence each joint should have on each node. This is where weight painting comes in, so you can start assigning the right influence manually.
Move joints to represent the influence.
When you start the skinning process, it makes sense to just start working first. Start from one part of the model, make sure you have a good look and then move on to the next part.
Instead of trying to paint each node correctly, you can apply a standard binding and simply start moving each connection and making sure it deforms and affects your mesh exactly the way you want it to. You can even start by creating very simple animations on your rig, moving each joint and then going back and studying the animation carefully. Most likely, you’ll start to see deformation problems and joints that don’t have the right impact on your model. This will allow you to easily identify the problem areas and on this basis solve the skinning problems by painting the weights. This means you can focus on the areas that need the most work.
Mirroring the weights.
Proper skinning of your equipment can be a very tedious and time-consuming process. Mirroring your skin weights may save you a lot of work. For example, you may have spent hours painting the weights on your left arm to make it look perfect. Spending the same time on the right arm can seem like a waste, as both areas may need the same influence as each joint. By mirroring, you can simply copy the weights of the left arm to the right arm and in a few minutes the right arm will deform exactly as you want it to, without actually having to pull any more.
Make sure your nodes are brought together.
With skinning, you assign each binding an influence on the corners of your model, to avoid problems you should always make sure that all corners of your mesh are joined together. When you start painting weights with corners that are not connected, it creates holes in your mesh, and you will usually only be able to see these holes when you paint the weights, so you will have to undo all your work. To avoid this problem, simply check all the nodes you think have not been merged or areas you forgot. Skinning can be a long process, but if you understand it better and consider these techniques, you will speed up your workflow. To get deeper into the subject, you should study the speed skinning techniques in Maya and further develop your skills through a variety of additional rigging tutorials.
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