| Summary: | G4TessellatedSolid::Inside reports erroneous results | ||
|---|---|---|---|
| Product: | Geant4 | Reporter: | rickard.holmberg |
| Component: | geometry/solids | Assignee: | flei |
| Status: | RESOLVED FIXED | ||
| Severity: | normal | CC: | Gabriele.Cosmo |
| Priority: | P2 | ||
| Version: | other | ||
| Hardware: | PC | ||
| OS: | Linux | ||
| URL: | http://avkrok.net/~rickard/geant4/ | ||
I have a "works-for-me" fix for this problem now. Available from the "additional informations" URL or directly as http://avkrok.net/~rickard/geant4/current-tessellation.diff If someone could take a look at that patch and comment/verify/correct it I would be very grateful. The problem is now fixed in tag "geom-specific-V09-00-06" and will be included in the next public release. Thanks for the useful feedback and proposed solution. |
I am having some problems when trying to use the G4TessellatedSolid. It seems that some points supposedly inside of the defined volume are considered to lie outside by G4TessellatedSolid::Inside(), as reported by running with geometry/navigator/check_mode 1. The error that I get is *** G4Exception : FarOutsideCurrentVolume issued by : G4NormalNavigation::ComputeStep() Point is far outside Current Volume ! *** Fatal Exception *** core dump *** A larger snippet of the output is available at http://avkrok.net/~rickard/geant4/log , together with the gdml files used at http://avkrok.net/~rickard/geant4/geometry.gdml and http://avkrok.net/~rickard/geant4/testblock.gdml . I have tried to verify that all of my triangles are correctly oriented, by checking that each edge is used twice (once in each direction) and looking at one triangle to verify that it is correctly oriented. Looking at G4TessellatedSolid::Inside(), I think that at least part of the problem lies in the algorithm chosen for deciding what lies inside of the volume. As far as I can see, that method looks at the faces closest to the point (with a tolerance of kCarTolerance/2), plus one face further away (due to the itcut++ on line 357 in source/geometry/solids/specific/src/G4TessellatedSolid.cc), and if the point lies outside of any of the planes of the faces, the point is considered to lie outside of the volume. To the best of my understanding, that could not work for concave volumes with internal acute angles. A draft of an alternative algorithm is available from the URL attached, together with some sketches of my debugging of this problem so far.