swept surfaces

testing of Newton iteration as part of curve/surface intersection algorithms

further optimization of solid tracking algorithm

BREP libs consist of 7 basic solids and 1 generic solid

STEP defines only generic solids (inefficient for tracking)

Solids are read in as generic and conversions done later

import of geometry files from CAD systems via the NIST STEP toolkit

(CAD=Computer Aided Design)

Successful import tests done with STEP files from Euclid and ProEngineer

A general approach to plug in any STEP toolkit is under work

BREP library contains ISO STEP AP203 compliant geometric entities

supports tracking in boundary represented solids

Imports solid based detector models from CAD systems using STEP

Physical Volumes: positioned

• a logical volume placed (in another logical volume)

Logical Volumes: attributes

• Solid, sensitivity, visualisation attr.

Solids: geometrical properties

• shape and size

Constructed Solids (CSGs)

• Boxes, Cylinders, Spherical shells

Boundary Represented (BREPs)

• any 2nd order or NURBS surface

Swept solids

User defined: 6 functions

• inside, distance in/out (x2), extent

BREP=Boundary Represented Solid

Listing all its surfaces specifies a solid

• eg 6 squares for a cube

Surfaces can be

• planar or 2nd order
• higher order, Non-Uniform B-Splines (NURBS)

Solids in Geant-4

What are BREPs ?

The STEP standard

Interface to current CAD systems

Future work