Variance Surfaces

Variance surfaces feature are a way to create non-planar/uniform surfaces that may be used in CSG functions.  A moderate degree of tessellation and displacement using a vertex fractal method are used to create non-planar surfaces with 'variation'. 

Creating a Variance Surface Object

Choose Variance Surfaces option when creating an object, supported for Rectangle, Cylinder, Cone Shapes

Variance Surface Settings

With a displacement map object selected as Object A, open Object Effects dialog with Window: Object Effects menu option and choose "Var. Surfaces" tab.

Partition Degree: Relative tessellation degree of objects surfaces* 
Vertex Displacement: Relative amount vertices are displaced*
*Actual amounts are determined & scaled based on the object's dimensions
Use Render: Wireframe view to observe partition degree

Vertex Fractal: Frequency/Persistence controls profile of fractal applied to objects' vertices, graph is shown as a visual depiction.

Displacement Region Mask: Controls relative degree of vertex displacement for a region of an object.  Defaults to covering entire object region.  White areas represent full degree of displacement, black areas are where no vertex displacement is applied.  Mask acts as a cylindrical style texture around object.

As shown, left is no mask region (white), right is using region mask gradient to apply vertex displacement mainly on lower regions of cylinder shape.

Using Variance Surfaces

Variance surface objects can be used to create 'rough cut' shapes.  For example a pillar shape that appears broken

Cylinder Shape with variance surface Rectangle shape used in CSG difference, result on right.