4.7 The CMS Event Display

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This page is now obsolete, please go to WorkBookFireworks

Goals of this page

This page describes how to use the IGUANA-based CMS event display. IGUANA (Interactive Graphics and User ANAlysis) is a visualization framework for CMS reconstruction and simulation. It is aimed at CMS PRS physicists wishing to use the visualization based on the CMS Event Data Model (EDM) and in the CMSSW Framework.

Contents

• Introduction
• Local or Remote running
• Getting Started
• Run IGUANA
• Application Main Window
  • MDI Workspace
  • Menu Bar
  • Tool Bar
  • Tree Browser
  • Event Navigation
• Configuration File
  • CMS Simulation Geometry and Magnetic Field Visualization
  • CMS Fast Simulation Visualization
  • CMS Reconstruction Geometry Visualization
  • CMS Release Validation Samples Visualization
  • CMS Raw Data Visualization
  • Event Display Configuration
    • Number of Windows
    • What is Loaded
    • What is Displayed
    • Automatic Event Fetching
    • Energy Cuts
    • Annotations
    • Lego Scale
    • Full Screen Mode
    • Ignoring CMSSW Exception Messages
  • Content Proxies
• Event Display Examples
  • Magnetic Field Example
  • Fast Simulation Example
• Troubleshooting
  • Empty Parameter Set File
  • Framework Exceptions
• Information Sources
• Review Status

Introduction

The visualization system in the CMSSW project provides several interactive applications for CMS reconstruction and simulation. These visualization applications allow you to display CMS events and geometry and debug the algorithms/code which produce them. The system is based on an IGUANA framework, an IGUANA toolkit of 2D and 3D graphics and user interface components.

This WorkBook page does not assume prior expertise in either CMSSW or C++. If running on a system at CERN (or other institution where IGUANA is installed), no installation of software is required; you can just start visualizing.

Local or Remote running

Before setting up your area to run the CMS visualization, you should first consider:

• Can you gain additional performance by choosing to run IGUANA CMSSW locally?
• Do you have enough memory? (ideally 2Gb should be enough, but you never know how much CMSSW reconstruction may need in the future :-))
• Is the graphics card on your computer which runs an X server installed properly and with enabled 3D acceleration?
• Is the network connection is good enough to be able to run CMSSW visualization remotely?

See Scientific Linux CERN 4 Documentation for more information.

If you plan to run visualization frequently, you'll need to address these issues and possibly involve your sysadmin in order to get the best performance out of your system.

Remote running from a Windows box

If you run Windows on your box, one of the X servers which enable 3D acceleration is Exceed with Exceed3D (necessary). Install Exceed3D on a Windows machine, then the Exceed Xconfig command gives one various options: "Enable OpenGL" (necessary), "direct rendering" (necessary for local display), and "GLX 1.3 Support" (a good idea).

You can also set the environment variable "COIN_FULL_DIRECT_RENDERING = 1".

To check if you have OpenGL working successfully, type glxinfo and see if it gives any errors. Also type glxgears and see if a moving picture is displayed. (If these commands don't exist on your system, try looking in /usr/bin/X11/).

Getting Started

Set your runtime environment (shown for release %WBRELEASENEW%):
cd CMSSW_%WBRELEASENEW%/src
cmsenv

• Full instructions
• Summary for every login session
• Access modules from the CVS repository.

Before you try to run IGUANA, check that your Python configuration file (py file) is ok. Run cmsRun or python -i with it first and make sure the outcome is successful. Please refer to Introduction to CMS Configuration Files for information on defining configuration files.

In the configuration file you need to define a data source, for example, a PoolSource or an EmptySource, and a geometry source. The latter may require adding the event setup producers. See examples in the Configuration File section.

If you give a root file on the command line, Iguana will produce a configuration file for you. Note, you may need to modify it to set a proper CMS.GlobalTag.

Run IGUANA

To run IGUANA, simply type:

iguana your_cfg.py

if you already have a configuration file. You can ask iguana to make a your_cfg.py file for you:

iguana yourDataFile.root

The configuration file will have a time stamp in its name. You can use it as described above.

Iguana will start loading pre-defined plug-ins. When it's done, the main window will become active (see Application Main Window) and you can ask for an event from the menu Event->Next Event:

Application Main Window

The default layout of the event display application is shown below:

The application main window is divided by separators into three areas:

• an MDI (Multi Document Interface) workspace with a 2D browser (on the right),
• a tree-structure (Twig) browser (top left)
• and a text info window (bottom left).

The menu bar hosts loaded services. The tool bar provides short-cuts to most common actions (see Tool Bar section). The Twig browser shows the list of loaded Twigs (e.g. objects). They can be selected and made visible. The text info window will show a reach text output for selected objects. The status bar will show an event and run number and also a trigger information when it is available.

Right mouse click on a browser window will pop up a menu:

This menu can set different types of the object transparency and representations: wireframe, points, bounding box, etc.

MDI Workspace

The workspace can be configured to host multiple browsers: 3D, 2D (RPhi and RZ), Lego. This can be set either in a configuration file (see Number of Windows section) or interactively from "File"->"New..." menu:

After opening a Lego window:

To switch among the windows or tile them, use "Window" menu:

Menu Bar

The menu bar contains the pull down menus.

File Menu

Use the File pull down menu to save, print the scene, pop up the control centre GUI, add more windows, or end the session.

Save as... saves the displayed scene in an Open Inventor (.iv) file format. Clicking on the menu will pop up a file dialog to select the name and the location of the file.

Print as... prints the displayed scene in vector PostScript or raster formats. Clicking on the menu will pop up a file dialog to select the name and the location of the file and the file format.

Control Centre menu pops up a Control Centre GUI.

New menu can be used to add a 3D, RPhi, RZ, or Lego window.

Quit ends the session.

Tool Bar

Some of the more frequently used actions from the menu bar are available from the tool bar. The actions are performed on a selected browser in the workspace. If an action cannot be performed on the selected browser, the button will be disabled (grayed out). Certain buttons will change a mode of operation: for example, select or view mode. In this case, the button will remain pressed.

Save as button Save the scene graph in OpenInventor iv format for later viewing with a light weight iguana application - "Vis Example -- Open Inventor File Reader".

Print the scene graph button Print the picture displayed in selected browser. A scene from selected browser can be printed as a vector postscript (recommended) or a raster image: jpeg, tiff, png, etc.

Control centre button Show Control Centre.

Zoom in Zoom closer to the scene.

Zoom out Zoom father from the scene.

Pick/Select Mode Selects object manipulation or pick mode (and deselects camera or view mode). The cursor shape will change to an arrow. In this mode, the user is manipulating objects in the scene graph. Seek button is disabled in this mode.

View Mode Selects camera or view mode (and disables object manipulation or pick mode). The cursor shape will change to two half circle arrows. In this mode the user is moving the camera in 3D space.

Seek Mode Allows the user to select a new center of rotation for the camera. When clicked on (and in viewer mode) the cursor changes to a cross-hair. The next left mouse button-press causes whatever is underneath the cursor to be selected as the new center of rotation. Once the button is released, the camera either jumps or animates to its new position depending on the current setting of the seek time in the preferences dialog box.

Go Home Returns the camera to its home position (initial position if not reset).

Set Home Resets the home position to the current camera position.

View All Brings the entire scene graph into view.

Align with XY, ZX, or ZY plane Select the axis of alignment (Z, Y, or X) of the camera. Only displayed for Plane Viewers.

Auto Print Print a png image without poping up a file dialog. The name of the file will be a snapshot with a time and date stamp.

Grid Shows/hides a 1 m by 1 m grid.

Show visual feedback Show/Hide feed back axis on the scene graph.

Invert viewpoint Invert the camera through origin i.e rotate the camera 180 degree anti-clockwise.

Change projection Selects the type of camera used by the viewer. It toggles between the two available camera types -- perspective and orthographic. Only displayed for Examiner and Plane viewers.

Print the default views Print a vector postscript picture for each view point from a viewpoint list.

Tree Browser

The tree browser shows a hierarchy of objects which can be visualized and inspected. The left column of the tree browser contains a hierarchical list of the objects with their names, the right column contains a visibility checkbox associated with each object. The tick mark within the checkbox indicates that the object is visible. By clicking on the checkbox the user controls visibility of the object.

If the object has children, the small box with plus sign appears on the left of the name. The user can expand the branch either by clicking on the box (the plus sign will change to the minus sign) or by double click on the name. Some of the children may appear grayed out (disabled). The disabled objects can not be visualized. To enable the objects, open the object menu and choose "Enable".

The content of the tree browser may change from one event to the next. The picture on the left shows the simulated geometry tree browser in the event display simulation application first before the user asked for the first event, and to its right, after. The Geant4 geometry is created on the first event and the "Detector" tree branch is populated with a few branches corresponding to the top geometry volumes.

The data collection branches will be expanded and the number of objects in the collection will be shown in square brackets. [N/A] means that the collection is registered in the event, but not available (not stored?). The input tag of the collection is in brackets and is attached to the name.

When the user ticks the visibility checkbox and does not see the object, she/he may try to bring it in the view by clicking on the view all button in the toolbar. If the object is still not visible, it means that it does not have a suitable format for the view representation. For example, it may be a directory.

Right mouse click on the name will popup a menu.

Event Navigation

The Event menu from the menu bar provides several options for the event navigation:

Next Event will fetch a next event.

Previous Event will go back to the previous event.

Auto Events when the tick is set it will automatically fetch an event every 3 seconds (the time delay is configurable).

Goto Event... will pop up a dialog where the user will be asked to enter the run and event number.

Rewind will go to the first event in the file.

Skip... will pop up a dialog where the user will be asked to enter the number of events to skip and in which direction (back or forward).

Configuration File

To display CMS events iguana needs a configuration file with event source and event setup (e.g. detector geometries). The following sections illustrate how to construct a configuration file for a specific task. The configuration files mentioned beneath can be checked out from the CMSSW CVS repository:

> project CMSSW
> cd CMSSW_3_3_X/src
> cvs co VisDocumentation/VisTutorial
> cd VisDocumentation/VisTutorial

CMS Simulation Geometry and Magnetic Field Visualization

This file can be used to visualize the simulation geometry and the magnetic field.

Use it with

> iguana -p cmssw-geom_cfg.py

When a session GUI pops up, choose "CMSSW Simulation".

import FWCore.ParameterSet.Config as cms

from FWCore.MessageLogger.MessageLogger_cfi import *
process = cms.Process("IGUANA")
process.load("Configuration.StandardSequences.Geometry_cff")
process.load("Configuration.StandardSequences.MagneticField_cff")

process.VisConfigurationService = cms.Service("VisConfigurationService",
                  Views = cms.untracked.vstring('3D Window'),
                  ContentProxies = cms.untracked.vstring('Simulation/Core', 
                                                   'Simulation/Geometry', 
                                                   'Reco/CMS Magnetic Field')
                                              )

process.maxEvents = cms.untracked.PSet(
    input = cms.untracked.int32(1)
    )
process.source = cms.Source("EmptySource")

process.prod = cms.EDProducer("GeometryProducer",
                              CMS.MagneticField = cms.PSet(
    delta = cms.double(1.0)
    ),
                              UseMagneticField = cms.bool(False),
                              UseSensitiveDetectors = cms.bool(False)
                              )

process.p = cms.Path(process.prod)

CMS Fast Simulation Visualization

import FWCore.ParameterSet.Config as cms

process = cms.Process("PROD")

process.maxEvents = cms.untracked.PSet( input = cms.untracked.int32(100) )
process.load("FastSimulation/Configuration/RandomServiceInitialization_cff")

# Generate H -> ZZ -> l+l- l'+l'- (l,l'=e or mu), with mH=180GeV/c2
process.load("FastSimulation/Configuration/HZZllll_cfi")

# Famos sequences (Frontier conditions)
process.load("FastSimulation/Configuration/CommonInputsFake_cff")
process.load("FastSimulation/Configuration/FamosSequences_cff")

# Parametrized magnetic field (new mapping, 4.0 and 3.8T)
#process.load("Configuration.StandardSequences.MagneticField_40T_cff")
process.load("Configuration.StandardSequences.MagneticField_38T_cff")
process.VolumeBasedMagneticFieldESProducer.useParametrizedTrackerField = True

# If you want to turn on/off pile-up
process.famosPileUp.PileUpSimulator.averageNumber = 5.0    
# You may not want to simulate everything for your study
process.famosSimHits.SimulateCalorimetry = True
process.famosSimHits.SimulateTracking = True
# process.famosSimHits.SimulateMuons = False

# Produce Tracks and Clusters
process.p1 = cms.Path(process.famosWithTracksAndEcalClusters)

# Make the job crash in case of missing product
process.options = cms.untracked.PSet( Rethrow = cms.untracked.vstring('ProductNotFound') )

# Additional modules needed for IGUANA:
process.load("Configuration.StandardSequences.FakeConditions_cff")
process.load("CMS.RecoLocalTracker.SiPixelRecHits.PixelCPEGeneric_cfi")
process.load("VisFramework.VisFrameworkBase.VisConfigurationService_cff") 

CMS Reconstruction Geometry Visualization

import FWCore.ParameterSet.Config as cms

from FWCore.MessageLogger.MessageLogger_cfi import *
process = cms.Process("IGUANA")
process.load("Configuration.StandardSequences.FakeConditions_cff")
process.load("Configuration.StandardSequences.Geometry_cff")
process.load("Configuration.StandardSequences.MagneticField_cff")
process.load("Configuration.StandardSequences.Reconstruction_cff")

process.load("VisFramework.VisFrameworkBase.VisConfigurationService_cff")

process.source = cms.Source("EmptySource")

CMS Release Validation Samples Visualization

import FWCore.ParameterSet.Config as cms

process = cms.Process("IGUANA")

process.load("Configuration.StandardSequences.Geometry_cff")
process.load("Configuration.StandardSequences.MagneticField_cff")
process.load("Configuration.StandardSequences.Reconstruction_cff")
process.load("Configuration.StandardSequences.FrontierConditions_CMS.GlobalTag_cff")

process.source = cms.Source("PoolSource",
    firstEvent = cms.untracked.uint32(55),
    firstRun = cms.untracked.uint32(30),
    fileNames = cms.untracked.vstring('/store/relval/2008/6/9/
RelVal-RelValH200ZZ4L-1212539383-STARTUP-2nd-02/0001/
00C61FC1-0B37-DD11-9823-0018F3C3E3A6.root')
)

process.load("VisFramework.VisFrameworkBase.VisConfigurationService_cff")

VisConfigurationService_cff configuration file fragment contains description of the event display configuration.

CMS Raw Data Visualization

Event display cannot display raw data, but it run raw data unpacking and reconstruction on the fly. One can use standard sequences for that.

import FWCore.ParameterSet.Config as cms

process = cms.Process("IGUANA") 
process.load("Configuration.StandardSequences.Geometry_cff") 
process.load("Configuration.StandardSequences.MagneticField_30T_cff") 
process.load("Configuration.StandardSequences.ReconstructionCosmics_cff")
process.load("Configuration.StandardSequences.RawToDigi_cff")
 
process.source = cms.Source("PoolSource",
    firstEvent = cms.untracked.uint32(11732),
    firstRun = cms.untracked.uint32(1),
    fileNames = cms.untracked.vstring('rfio:/castor/cern.ch/user/b/boudoul/219/Cosmic0T
/GenSimRaw/CosmicGenSimRaw0T_149.root')
)

from FWCore.MessageLogger.MessageLogger_cfi import * 

process.load("Configuration.StandardSequences.FakeConditions_cff")

process.load("VisFramework.VisFrameworkBase.VisConfigurationService_cff") 
process.VisConfigurationService.VisAutoStart = False 
process.VisConfigurationService.VisCaloAnnotation = False 
process.VisConfigurationService.EnabledTwigs = (
                          '/Objects/CMS Event and Detector/Muon DT Event/DT 4DSegment', 
                          '/Objects/CMS Event and Detector/Muon RPC Event/RPC RecHit', 
                          '*ECAL Event/Rec hits*', 
                          '*Pixel Digi*', 
                          '*SiStrip Digi*', 
                          '*SiStrip Cluster*', 
                          '/Objects/Event Collections/Run and Event Number' 
                          ) 
process.VisConfigurationService.ContentProxies = ('Framework/EventSetup', 
                                                  'Reco/MuonDT', 
                                                  'Reco/CMS.MuonCSC', 
                                                  'Reco/CMS.MuonRPC', 
                                                  'Reco/Ecal', 
                                                  'Reco/Hcal', 
                                                  'Reco/Tracker', 
                                                  'Reco/Muon', 
                                                  'Reco/Jets', 
                                                  'Reco/Detector'
                                                  )
process.p = cms.Path( process.RawToDigi * process.reconstructionCosmics)

• If you are running on real data replace this line:

process.load("Configuration.StandardSequences.ReconstructionCosmics_cff")

with this one:

process.load("Configuration.StandardSequences.Reconstruction_cff") 

and modify the path to:

process.p = cms.Path( process.RawToDigi * process.reconstruction)

• If you are running on real data replace this line:

process.load("Configuration.StandardSequences.RawToDigi_cff") 

with the following fragment :

process.load("Configuration.StandardSequences.RawToDigi_Data_cff")

and modify the path to:

process.p = cms.Path( process.RawToDigi_woGCT * process.reconstructionCosmics)

• If you are running on real data replace this line:

 
process.load("Configuration.StandardSequences.FakeConditions_cff")

with the following fragment:

process.load("Configuration.StandardSequences.FrontierConditions_CMS.GlobalTag_cff") 
process.prefer("CMS.GlobalTag") 
process.GlobalTag.connect = "frontier://PromptProd/CMS_COND_21X_GLOBALTAG"
process.GlobalTag.globaltag = "CRUZET4_V5P::All"

Event Display Configuration

Event display can be configured via a parameter set file which is given to iguana as a command line option. The user should include a VisConfigurationService service fragment in the configuration file. This defines a startup configuration of the event display. The user can define various windows to be popped up and tiled, additional services to load, whether or not to load the text browser and the tree browser, and which leaves of the tree to be set visible. The following example shows a startup configuration with one RPhi window and one RZ window (Views parameter), with the text browser and the tree browser loaded (TextBrowser and TwigBrowser parameters have the default values), a configuration of the loaded plugins (ContentProxies parameter), and a list of leaves (i.e. detectors and reco/sim objects) which will be set visible (EnabledTwigs parameter):

process.load("VisFramework.VisFrameworkBase.VisConfigurationService_cff")

Number of Windows

Number of various windows to be popped up and tiled defined by an untracked vstring Views which can be any number of the following strings: '3D Window', 'Lego Window', 'RPhi Window', 'RZ Window'. For example:

process.VisConfigurationService.Views = ('RPhi Window', 'RZ Window')

What is Loaded

The ContentProxies parameter defines the list of plugins which will be loaded. For, example, if the user is interested in visualizing only the DT sub-detector, she/he may set it as follows:

process.VisConfigurationService.ContentProxies = ('Framework/EventSetup',
                                                  'Reco/MuonDT',
                                                  'Reco/CMS.MuonCSC',
                                                  'Reco/CMS.MuonRPC',
                                                  'Reco/Ecal',
                                                  'Reco/Hcal',
                                                  'Reco/Tracker',
                                                  'Reco/Muon',
                                                  'Reco/Jets',
                                                  'Reco/Detector')

The less plugins loaded, the faster the application runs.

What is Displayed

Example of EnabledTwigs parameter:

process.VisConfigurationService.EnabledTwigs = (
                         '/Objects/CMS Event and Detector/Muon DT Event/DT 4DSegment',
                         '/Objects/CMS Event and Detector/Muon RPC Event/RPC RecHit',
                         '/Objects/CMS Event and Detector/Muon CSC Event/Segments')

You can also use "*" to define a more generic selection as shown beneath:

process.VisConfigurationService.EnabledTwigs = ('*SiStrip Digi*',
                                                '*cosmicMuons*',
                                                '*Segments*')

Automatic Event Fetching

You can start event display in auto event fetching mode by modifying VisAutoStart (the default is set to False):

process.VisConfigurationService.VisAutoStart = True

Use Event menu as described in Event Navigation section to switch this mode on or off.

The time delay between retrieving events can be changed by modifying VisEventTimer (the default is set to 30000):

process.VisConfigurationService.VisEventTimer = 50000

Energy Cuts

The following visualization cuts can be set in configuration file as well as modified interactively:

• VisCaloJetEnergyCut (default is 10 GeV)
• VisEcalEnergyCut (default is 0.1 GeV)
• VisEnergyCut (default is 1 GeV)
• VisHcalEnergyCut (default is 0.1 GeV)
• VisHFEnergyCut (default is 1.5 GeV)
• VisPtCut (default is 1 GeV)

For example:

process.VisConfigurationService.VisEcalEnergyCut = 1

Annotations

The following annotations can be set in configuration file as well as modified interactively:

• VisAnnotateGeometry (False)
• VisCaloAnnotation (True)
• VisMuonAnnotation (True)
• VisSimTrackAnnotation (True)

Lego Scale

The lego plot scale can be set in configuration file as well as modified interactively:

• VisLegoScale (default is 10 GeV)

For example:

process.VisConfigurationService.VisLegoScale = 1

Full Screen Mode

Event display in a full screen mode hides all the menus, window decorations, text and twig browsers. Only the MDI windows and a status bar are shown. To start event display in a full screen mode modify VisAppMode (default is "normal") to:

process.VisConfigurationService.VisAppMode = "full screen"

To switch from/to full screen mode hit "Esc".

You can also set it to "maximized" mode.

Ignoring CMSSW Exception Messages

Event display pops up a message widow every time it traps an exception. It displays an origin of the exception and the exception message. There are cases when a CMSSW exception can be safely ignored. For example, if the requested product is not found, but a user does not want to display it anyway. If you do not want to be disturbed by the popping up windows in this case, set the VisExceptionMessage parameter to "none" (default is "GUI").

process.VisConfigurationService.VisExceptionMessage = "none"

Content Proxies

The full list of content proxies available at run time can be obtained by executing the following command:

> iguana --list

The following content proxies can be used to visualize the corresponding data. (Warning: one currently can't specify Reco/Muon and Reco/Tracker simultaneously):

Content Proxy	Type	Description
Framework/EventSetup		Reconstructed geometry of DT, CSC, RPC, Tracker, ECAL and HCAL
	CaloGeometry	Reconstructed geometry of ECAL and HCAL
	GlobalTrackingGeometry
	TrackerGeometry	Reconstructed geometry of Tracker
	CSCGeometry	Reconstructed geometry of CSC
	DTGeometry	Reconstructed geometry of DT
	RPCGeometry	Reconstructed geometry of RPC
Reco/CMS Magnetic Field	VolumeBasedMagneticField	Magnetic field
Reco/Candidate	Candidate	Candidate display
Reco/CustomTracker		Custom tracker visualization: tracker geometry selector, etc.
Reco/Detector		CMS detector geometry
Reco/Ecal	EcalUncalibratedRecHit	ECAL rec hits visualization
	EcalRecHit
	BasicCluster
	SuperCluster
Reco/Hcal	HBHERecHit	HCAL rec hits and Lego detector (towers)
	HFRecHit
	HORecHit
Reco/Jets	CaloJet	Jet visualization
	CaloTower
	GenJet
	JetTagCollection
Reco/MET	MET	MET visualization
	CaloMET
	GenMET
Reco/Muon	Track	Track is displayed as its inner and outer states connected with a spline based on the directions in these points.
	Muon	Muon and its constituents
MuonCSC	CSCALCTDigi	CSC event data and CSC hierarchical geometry
	CSCCLCTDigi
	CSCComparatorDigi
	CSCCorrelatedLCTDigi
	CSCRPCDigi
	CMS.CSCRecHit2D
	CSCSegment
	CSCStripDigi
	CSCWireDigi
Reco/MuonDT	DTDigi	DT event data and DT hierarchical geometry
	DTRecHit1DPair
	DTSLRecSegment2D
	DTRecSegment4D
MuonRPC	RPCDigi	RPC event data and hierarchical geometry
	RPCRecHit
Reco/Tools		Propagation of a CSC segment to the HCAL tower
Reco/Tracker	PixelDigi
	SiStripDigi
	SiPixelCluster
	SiPixelRecHit
	SiStripRecHit2D
	SiStripMatchedRecHit2D
	SiStripCluster
	Track
	GsfTrack
	TrajectorySeed
	TrackingRecHit
Reco/Trigger	LTCDigi	Trigger mask
	L1MuDTChambPhContainer
	L1MuDTChambThContainer
	L1MuDTTrackContainer
	TriggerResults
Simulation/Data Formats	GenParticle	HepMC tree
	HepMCParticleTree
Simulation/Geometry	G4VPhysicalVolume	CMS Geant4 geometry
	G4LogicalVolume
Simulation/Hits	PCaloHit	Simulated data
	PSimHit
	SimTrack
	SimVertex
Simulation/MagField	G4Field	CMS Geant4 magnetic field

Event Display Examples

This section explains how to run some of the visualization applications.

Magnetic Field Example

To visualize the CMS magnetic field, use the parameter set (configuration) file as in the CMS Simulation Geometry and Magnetic Field Visualization section. The magnetic field will be constructed on the first event (ask Event->Next Event). Tick the visibility box of the "Magnetic field" leaf on. Align it with XZ axis (click on the tool bar button). Bring it all in the view by clicking on the view all toolbar button. Popup the control centre by clicking on the control centre toolbar button and open the Fields Planes folder (double mouse click on ). The control centre window will show the controls for manipulating the magnetic field plane. See the snapshot on the right.

Fast Simulation Example

To run fast simulation and visualize it on the fly, use the parameter set (configuration) file as in the CMS Fast Simulation Visualization section.

#CMS.TroubleShooting

Troubleshooting

It is important to check the consistency of your configuration file before you give it to iguana. To check it, firstly, run:

python -i your_cfg.py

If there are errors, fix them. Use Ctrl+D to exit from python interpreter.

Secondly, try to run cmsRun on it. If you get any exceptions, try to fix them first.

Empty Parameter set file

If there is no parameter set file given to the event display, or the file name was misspelled, or the file is not found, you will see the warning:

A default parameter set file with an EmptySource will be constructed for you. You will still be able to visualize some detectors, but no events.

Solution: Restart the event display with a correct parameter set file.

Framework Exceptions

Solution: Quit the event display and try again later.

Information Sources

Original material from

• Release-based Visualisation user guide

More comprehensive design, reference, planning and other documentation may be found on the IGUANA and CMSSW visualization web sites:

• IGUANA homepage
• IguanaCMS homepage

Help is available from the following sources:

• email to mailto:iguana-developers@cernNOSPAMPLEASE.ch
• Visualization Discussion hypernews

Review status

Reviewer/Editor and Date (copy from screen)	Comments
AnneHeavey - 11 Sep 2006	some rewording, fixed contents, inserted red questions (did not actually run it)
YanaOsborne - 17 Nov 2006	significant updates

Responsible: YanaOsborne
Last reviewed by: YanaOsborne - 22 Feb 2008