Detray: a compile time polymorphic tracking geometry description

Abstract

A detailed geometry description is essential to any high quality track reconstruction application. In current C++ based track reconstruction software libraries this is often achieved by an object oriented, polymorphic geometry description that implements different shapes and objects by extending a common base class. Such a design, however, has been shown to be problematic when attempting to adapt these applications to run on heterogeneous computing hardware, particularly on hardware accelerators. We present detray, a compile time polymorphic and yet accurate track reconstruction geometry description which is part of the ACTS parallelization R&D effort. detray is built as an index based geometry description with a shallow memory layout, that uses variadic template programming to allow custom shapes and intersection algorithms rather than inheritance from abstract base classes. It is designed to serve as a potential geometry and navigation backend for ACTS and as such implements the ACTS navigation model of boundary portals and purely surface based geometric entities. detray is designed to work with a dedicated memory management library and thus can be instantiated as a geometry model in host and device code.

Surface-based GPU-friendly geometry modeling for detector simulation

“…Adopting a boundary representation (BREP) model [7] allows decomposing navigation tasks into simple surface queries. After careful evaluation of the GPU-aware solutions available in the community, such as ORANGE [8] and detray [9], we decided to develop a custom surface model adapted to the Geant topological constraints and using a bounded surface representation. The model supports first and second-order half-spaces bounded by frames delimiting the faces of the 3D solids.…”