Using method by example the linear blend skinning algorithm works by frst placing a hierarchical skeleton in this case a 2 chain upper and lower arm. inside a static model of a character mesh, our arm typically polygonal, this is typically a neutral t-pose.referreded to as dress. It allows easy access for weighting and the manipulation of the character

Each vertex on the mesh is assigned a set of infuencing joints and a blending weight. Computing the deformation in
some pose involves rigidly transforming each dress pose vertex by all of its infuencing joints. Then the blending weights are used to combine these rigidly transformed positions.

Enveloping provides a stable and robust system due to its age. Catmull [1972] introduced one of the frst skeleton-driven techniques rigid skinning. It is a well documented process, with simple tutorials to advanced methods of exploration to more efficient deformations. It is transferable across packages and requires no external plugins

This method is simple and easy to compute therefore very fast however the user needs to input the weights of each influence object, predominatly the bones. This can be done using numerical values via the weight editor or interactivly via the weight paint tool. The process can be tedious and time consuming in more complex areas. Especially on meshes with insufficient topolgy.

Artifats occur because vertices are transformed by linearly interpolated matrices.
If the interpolated matrices are dissimilar as in a rotation of
nearly 180 degrees, the interpolated transformation is degenerate, so the geometry must collapse. In addition to these deformation problems, linear blend skins are very diffcult to author [Lewis et al. 2000].(chils.M]

Deformation effect could be obtained by adding joints that deform appropriately to capture muscle bulges. Joints that scale up when the muscle should bulge, and scale down when the muscle relaxes. For wrinkles, we could add several joints that move and scale in concert to capture the wrinkles, the limit we could add as many transformations as vertices and capture all deformations exactly.however there are more practical soloutions, this number of joints severely impacting performance and managebility

Despite its failings, this skinning algorithm is very fast and
widely supported by commercial applications so it remains popular especially in games and virtual environments.
4 Extending Linear Blend Skinning