3D Geometry in TouchDesigner is held in SOPs, and is stored in the data structure called a Geometry Detail. The Geometry Detail holds a a Point List, a Primitive, and for each Polygon/Spline-type primitive, it holds a Vertex List. The types of primitives are polygon, mesh, spline, metaballs, spheres, cylinders and particles.

Geometry is rendered to an image by the Render TOP, which takes a set of Geometry Component that contain SOPs whose Render flags are on.

Here are the details on the types of geometry that TouchDesigner is capable of rendering.