Message: Re: Smart voxelization for parameterised volume Not Logged In (login)
 Next-in-Thread Next-in-Thread
 Next-in-Forum Next-in-Forum

None Re: Smart voxelization for parameterised volume 

Forum: Geometry
Re: None Smart voxelization for parameterised volume
Re: More Re: Smart voxelization for parameterised volume (Gabriele Cosmo)
Re: None Re: Smart voxelization for parameterised volume
Date: 13 Jan, 2016
From: John Apostolakis <John Apostolakis>

Dear Anders,

Thanks for the explanation of your application.

Within each Geant4 run (i.e. /run/beamOn X ) the Geant4 geometry expects that all volumes are either:
  - do not move with respect to its parent, or
  - are contained within a parent which is not voxelized.

Volumes which are voxelised created an auxliary data structure which speeds up navigation.  The voxelisation must be rebuilt each time the location of any of the daughter volumes is changed.  Else you will get incorrect navigation.

>> Your parameterisation must be 'predictable', such that dimensions and positions can be reproduced for the same run.
> 
> The dimensions for a given copyNo do not change. The position for a given copyNo changes between events, but not within an event. Does this fulfill the predictability criterion ?

Have you investigated making each event be a separate Geant4 run ?

Best regards,
John
===================================================
John Apostolakis,  PH Department, CERN

> On 13 Jan 2016, at 19:10, anders.floderus@gmail.com wrote:
> 
> 
> *** Discussion title: Geometry
> 
> Hi Gabriele,
> 
> Thanks for your reply! Let me clarify.
> 
>> if with your parameterisation you generate a sphere randomly,
>> then you cannot use the voxelisation, as the voxels structure gets
>> generated statically at the beginning and does not change during the
>> run.
> 
> At the start of my program, I read in a text file that contains some randomly generated coordinates. The coordinates are stored in a
> container class that returns a coordinate as a function of the event number. An instance of this class is then copied to wherever it is
> needed (e.g. PrimaryGeneratorAction and the parameterised volume). The "random coordinate" is thus uniquely defined by the event number and
> does not change within an event. It is not the case that I generate a new coordinate for each call to ComputeTransformation.
> 
>> Your parameterisation must be 'predictable', such that dimensions and positions can be reproduced for the same run.
> 
> The dimensions for a given copyNo do not change. The position for a given copyNo changes between events, but not within an event. Does this fulfill the predictability criterion ?


>> Note also that parameterisations can only apply to a single volume (associated to a solid) and you cannot have two parameterisations
>> daughters of the same mother.
> 
> The mother volume has only one parameterised daughter. It is a G4Sphere whose dimensions depend on the copyNo. For the sake of example, let's
> say copyNo 0 has rMin = 0 and rMax = 5mm while copyNo 1 has rMin = 5mm and rMax = 10mm. I plan to simulate multiple balls in the future (each
> one would add an additional two copies to the parameterisation), but the problem is present with just one.
> 
> // Anders
> 
> -------------------------------------------------------------
> Visit this GEANT4 at hypernews.slac.stanford.edu message (to reply or unsubscribe) at: 
> http://hypernews.slac.stanford.edu/HyperNews/geant4/get/geometry/1447/1/1.html 

Inline Depth:
 1 1
 All All
Outline Depth:
 1 1
 2 2
 All All
Add message: (add)

1 None: Re: Smart voxelization for parameterised volume   (herr_apa - 21 Jan, 2016)
 Add Message Add Message
to: "Re: Smart voxelization for parameterised volume"

 Subscribe Subscribe

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 ]