Created attachment 458 [details] Example constructing two nested cones and running the overlap checker. In a geometry configuration of two nested cones, the overlap checker ("geometry/test/run") gives different results depending on whether one of the cones is rotated by pi + R*1 / R*2 are interchanged or not (which should in principle be equivalent). See the attachment for a complete testcase. Note that this problem seems to be version specific. It seems to be present in 10.2 / the version that is in LCG release 88, but not in 10.1. I didn't test any other versions.
We cannot reproduce the problem, using a vanilla installation of Geant4 (either 10.2 or more recent). The overlap check behaves as expected. Looking at the setup being used, based on the LCG build of Geant4-10.2.p02 at CERN, I noticed the LCG_88 build is making use of the VecGeom library, to replace the original shapes implementation in Geant4. The problem is therefore affecting VecGeom itself. I'm closing this ticket and transferring it to VecGeom JIRA.
JIRA ticket open for VecGeom: https://its.cern.ch/jira/browse/VECGEOM-433
