Modifiers: Shell

The Shell Modifier converts a normal mesh into a shell with user defined thickness.

The shell thickness can be set as a function of distance in the Magnitude dialog. Note that the shell can be generated outwards (positive) or inwards (negative) of the original mesh by changing the sign of the magnitude. Currently the magnitude can only be changed as a function of distance from the world coordinate center. This might change in future releases.

The magnitude dialog allows you to define the thickness as an Analytic Function of distance or use a graph where you can generate an arbitrary function by manually placing points and setting the spline interpolation. The graph on the right shows the way it was done in this example. Note that only the newly generated mesh is affected by the shell modifier.

In the three pictures above the mesh is shown for three different settings. The first one on the left has both parts of the shell enabled. For the second one, the Outer geo flag was disabled. Therefore only the original object mesh remains. On the right, however, the Inner geo flag was disabled. Then the new shell mesh is left. Now the rendered volume fill out the whole space within the outer mesh of what was a shell.

Note that the position in the Modifier Stack is important. If a Shell Modifier is placed at the end of the stack, the result will be a shell thickness that conforms to the Magnitude graph. However, if another geometry operator, such as a Bump Modifier or a Squish Modifier is placed below the Shell Modifier, then the final thickness may strongly different from that set up in the Shell Modifier.

Caution: If the original mesh is locally complex and the thickness similar or larger than the local curvature, then the newly created mesh for the shell may self-overlap. This can lead to undesirable results. Make sure the thickness of the shell is compatible with the complexity of the mesh. Sometimes applying the shell in the opposite direction by inverting the magnitude of the thickness solves or reduces this potential problem.

Modifiers: Shell