Message: Using Boolean Solids with Tessellated Solids Not Logged In (login)

## Using Boolean Solids with Tessellated Solids

Forum: Geometry
Date: 11 Aug, 2010
From: Daniel O'Brien <Daniel O'Brien>

 Hi everyone, I was wondering if anyone could help me. I'm attempted to generate a particular shape (a leaf from a multi-leaf collimator on a medical linac) which has a curved surface on one side and a flat jagged surface on the sides perpendicular to it. The most straightforward way of doing this was to create the jagged surface with a G4TessellatedSolid and the curved surface with a G4Tubs and use G4IntersectionSolid to combine them into the correct shape. This seemed to have the desired effect (although I cannot visualise the shape in OGLIX or HepRep, I determined if the shape was correct by writing a Geant4 simulation that essentially took an x-ray image of the shape), however during the course of the run I get the following warning repeatedly: ``` Solid name = MLC Leaf Steps Geometry Type = G4TessellatedSolid Number of facets = 14 Position:``` ``` p.x() = -13.05233040123778 mm p.y() = 55.5358564711038 mm p.z() = -3.5 mm``` ``` *** G4Exception : UnknownInsideOutside issued by : G4TessellatedSolid::Inside() Cannot determine whether point is inside or outside volume! *** This is just a warning message.``` Does anyone know why this is happening? It happens if I use the G4UnionSolid aswell. I'm completely confident that I have defined both components (the G4Tubs and the G4TessellatedSolid) correctly and using them individually produces no warnings or errors whatsoever. Perhaps more importantly is, should I be concerned about this? It says it's just a warning and the photon transport through the solid appears to be behaving as expected (as evidenced by my simple x-ray imaging program). I'd appreciate any help you can provide. Thanks in advance, Daniel

 Inline Depth: Outline Depth: Add message:

1 Re: Using Boolean Solids with Tessellated Solids   (Daniel O'Brien - 11 Aug, 2010)
 to: "Using Boolean Solids with Tessellated Solids"
This site runs SLAC HyperNews version 1.11-slac-98, derived from the original HyperNews

[ Geant 4 Home | Geant 4 HyperNews | Search | Request New Forum | Feedback ]