VisuDet < LinearCollider

LinearCollider Web>VisuDet (2014-06-24, DanProtopopescu) (raw view)
---+ Visualising a detector geometry

In order to implement and validate a detector geometry in DD4hep, it is important to be able to visualise it. This wiki explores the existing options. Lots of thanks to Nikiforos Nikiforou for explaining how everything works.

%TOC%

---++ Geometry description formats

There are various formats used to describe a detector geometry. 
The info in the =compact.xml= is not enough to describe the detector - drivers are needed to expand info from the XML and create all the volumes. Mokka or SLIC for example create ways of inputting objects in Geant4 without programming volumes in Geant4.

   * GDML (Geant4, ROOT)
   * LCDD (!GeomConverter) - LCDD is GDML augmented by sensitive detector info including cell id specs.
   * HEPREP
   * XML - all of the above are XML formats

---++ Format conversions

How to create the LCDD file:

From *GeomConverter* - start with !GeomConverter's =compact.xml= (from [[http://www.lcsim.org/detectors][here]], for example), use the java converter to produce the LCDD file:
<verbatim>
cd /afs/cern.ch/eng/clic/software/GeomConverter/GeomConverter-2_4/target
</verbatim>
Convert by doing
<verbatim>
java -jar GeomConverter-2.4-bin.jar -o lcdd <input> <output>
</verbatim>

One can then delete by hand all sensitive detector info to be left with a pure *GDML* file.

From *SLIC*, use
<verbatim>
slic -g clic-sid_cdr.lcdd
</verbatim>
for example to load the geometry in memory, then
<verbatim>
slic -G clic-sid_cdr.lcdd
</verbatim>
to dump the geometry. This allows to see *how SLIC loads the geometry*, basically debugging SLIC as well. %X% Beware of some bugs in SLIC related to assemblies and the order of rotations.
  
From *DD4hep*, use 
<verbatim>
geoConverter -compact2lcdd -input compact.xml -output dd4hep.lcdd
gGeoManager->Export(“clic-crr.gdml”) 
</verbatim>
or use =Export(“clic-crr.root”)= to export in ROOT format.

From *Mokka*, one can create a GDML file with 
<verbatim>
/Mokka/Visu/Detector/DumpGDML 
</verbatim>
By default this will dump the World volume (whole detector) in =World.gdml=. If one provides a subdetector as argument, it will dump just the subdetector. See the help function for more info.

%X% Beware of bug related to VACUUM material (delete the VACUUM and dummy entries by hand).  One can also create a Gear file etc.


---++ Visualisation

To visualise a *GDML* file in *ROOT*: open ROOT, then

<verbatim>
TGeoManager::Import(“myclic.gdml”);
gGeoManager->GetTopVolume()->Draw(“ogl”); 
</verbatim> 
where =ogl= selects the !OpenGL engine. All figures from [[ValidateGeom][this]] section were produced like that.

From *SLIC*, do
<verbatim>
source ~/ilc_soft/slic/v03-01-06/init_ilcsoft.sh 
slic -g clic-sid_cdr.lcdd -n
</verbatim>
to get a Geant4 prompt, i.e. a Geant4 interface with the geometry loaded; use Geant4 commands like to visualise the geometry:
<verbatim>
Idle> /vis/open OGL
Idle> /vis/scene/create 
Idle> /vis/drawVolume
Idle> /vis/viewer/set/viewpointThetaPhi 60 45
Idle> /vis/viewer/set/background white
</verbatim>
which, with [[http://lcsim.org/detectors/clic_sid_cdr.html][this]] geometry, will display something like this:

<img src="%PUBURLPATH%/%WEB%/%TOPIC%/slic-view.png" alt="slic-view.png" width="459" height="386" />

From *Mokka*, one can visualise the DB geometry via Geant4 as above. See [[https://twiki.ppe.gla.ac.uk/bin/view/LinearCollider/RunMokkaLocally#Visualisation][this]] example.

To visualise a HEPREP file use jas3. With the *SLIC* setup described above, one can see the GUI by doing:
<verbatim>
java -jar GeomConverter-2.4-bin.jar
</verbatim>
Attachments
Topic attachments
I	Attachment	History	Action	Size	Date	Who	Comment
png	slic-view.png	r1	manage	42.8 K	2014-06-24 - 13:57	DanProtopopescu	SLIC/Geant4 view of the clic_sid_cdr geometry
Topic revision: r5 - 2014-06-24 - DanProtopopescu
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