mtSubDivider generates subdivisions on base geometry.

Torus as a child of mtSubDivider, using a Noise shader with Subdivision layers set to 2.

Object tab

mtSubdivider, Object tab menu settings.

Selection Map

You can use vertex map or selection tags to define where subdivisions are generated.

Drag the tag from the Object Manager into the Selection Map link field.

The Plane on the left has a polygon selection tag, which is displayed in the viewport. An identical Plane is on the right, as a child of a mtSubdivider, driving the subdivisions.

The Plane on the left has a vertex map, which is displayed in the viewport. An identical Plane is on the right, as a child of a mtSubdivider. The vertex weights are driving the subdivisions.

Texture Source

You can use shaders, images and even animated video sequences to control where subdivisions are generated.

There are two options: Shader and Texture Tag.