Auto Weight
The Auto Weight tab is a powerful tool for automatic weighting. Here you will find all the settings required to automatically weight an entire character.
For simple to medium complexity characters, the automatic weighting is usually more than sufficient to create good deformation for the character. Even with complex characters, the auto weighting provides a good basis that you can then fine-tune in the critical areas. Either way, auto weighting can save hours of effort.
Several modes are available to calculate weights:
Calculates the vertex weights based on the straight distance of each point relative to each joint (each point is weighted/assigned to its closest joint, basically). This is the fastest mode to use and the best one for applying weights to the whole mesh quickly but tends to be inaccurate and often requires manual correction afterwards. Problem areas when using this mode are typically found around the shoulders and hips of a character, or when limbs are close together. Used in conjunction with the Bone Glow option, this algorithm usually offers pretty good results for its speed, in most cases.
RELEASE 21
This mode is an improved distance algorithm which by default should give you better results for its speed, as it uses a straight distance value combined with a visibility factor, that gradually falls off based on the length of the bone of each joint.
This mode will assign influence to the selected joints based on the volumes of the meshes surrounding them. The algorithm will fill volumes with voxels around each joint and map out their weights based on these voxels. This mode should be used with closed meshes, and with joints placed inside these meshes for best results. This mode is the slowest to calculate, but tends to be the most accurate.
Allows you to run the Auto Weighting algorithm without returning manually to the Bind pose each time. This is a great way to iterate or tweak parameters, then run the auto weighting algorithm without having to go back and forth between the posed and non-posed states of your character to check the resulting deformations.
Auto Weight will only affect selected points.
Allow Joints with a bone length of zero to be included in the auto weighting calculations (ie: joints outside any hierarchy or joints with a bone set to Null).
Here you define the maximum number of joints that can affect a given point. The more joints, the smoother the transitions, but also the longer it will take to calculate the weights.
Smoothing is automatically applied to the weights after they have been assigned by the auto weighting algorithms. Here you will find options to adjust the amount of smoothing that will be added.
Note that using these separate commands will not allow you to smooth weights between disconnected meshes, but smoothing directly from the Auto Weight command will.
Set the amount of smoothing applied to the weights. The higher the value, the smoother the transition between the weights of each joints.
How many smoothing passes are applied to the weights. It can be preferable to add passes for a more detailed smoothing in areas that have a lot of different weight values applied to various joints, as it will tend to preserve more details than increasing the smoothing strength (which will tend to blend the weight values of further points together).
Defines the amount of decay that will be applied to the weights of joints, based on their size and distance from the mesh they are influencing. This parameter is also used for smoothing.
Defines how far each joint influences the mesh it is assigned to. Greater values will affect points further from the joint. This value is proportional to the size of the bone of each joint. This parameter is also used for smoothing.
Distance / Volumetric settings
The following 3 settings will only be made available if Mode is set to Distance or Volumentric.
Bone Glow is a mix between distance and visibility values for each joint. It allows for the auto weight algorithm to not only calculate weights based on their distance from each joint, but also take into consideration what is visible from them. This is very useful when applying weight to the tongue of a character, for example, so that the joints placed inside of the tongue geometry will not affect the jaw or cheeks vertexes of the character, since they are not visible from these specific joints. It will also tend to give better results around the shoulders of a character, by preventing the arm joints from influencing points below the shoulder and impact the torso.
This option replaces the old Visibility mode (prior to CINEMA4D R21) and is both more accurate and faster to calculate.
Allow the Bone Glow algorithm to ignore polygons that are placed inside a mesh volume. This can be useful for the jaw area of a character, for example, so you can ignore weighting the tongue or teeth of your character without affecting the way the cheeks and jaw are weighted. This can be useful if you plan on using a different algorithm in that area, or just weight them later by hand.
Define how much of an impact visibility has on the weighting. The greater this value, the more of the bone length needs to be visible from any given point for it to be assigned some weight value. Lowers values will force the algorithm to rely on distance parameters more.
Sets the voxel size used in the Volumetric auto weighting algorithm automatically, based on the size of each separate mesh assigned to the selected joints. Each mesh will be assigned voxels sized as a best compromise between speed and quality.
This option only becomes active once Auto-Size per Object is disabled. It might be preferable to set your own voxel size for each mesh you are trying to apply auto weighting to, either to speed up the process, or increase its accuracy. Each mesh is different, so the Auto-Size per Object option might need to be overridden in some cases.
Starts the automatic weighting for your character using the options specified. In order for the automatic weighting to work, the object you want to create the weights for must have a Weight tag. This Weight tag must link to all the joints you want to use for the weighting.
Next, select either this object or any one of the joints that are linked to the Weight tag. Click on the Calculate button and in most cases you'll see an instant result. However, how long this takes depends on the complexity of the mesh, the auto weight mode chosen and the speed of your computer.