Geometry module
The ACTS geometry model is strongly based on the ATLAS Tracking geometry. Its core is built on a surface-based description that make up all geometry objects of higher complexity. This design has been chosen as the surface objects can be used together with the track propagation module and thus all geometry objects become natively integrated into the tracking software.
Note
There is an ongoing rewrite of the geometry and navigation modules where logical layers will be modelled as volumes, see Layerless geometry.