The Geant4 visualization system was developed in response to a diverse set of requirements:
Quick response to study geometries, trajectories and hits
High-quality output for publications
Flexible camera control to debug complex geometries
Tools to show volume overlap errors in detector geometries
Interactive picking to get more information on visualized objects
No one graphics system is ideal for all of these requirements, and many of the large software frameworks into which Geant4 has been incorporated already have their own visualization systems, so Geant4 visualization was designed around an abstract interface that supports a diverse family of graphics systems. Some of these graphics systems use a graphics library compiled with Geant4, such as OpenGL, while others involve a separate application, such as WIRED or DAWN.
Simulation data can be visualized:
Detector components
A hierarchical structure of physical volumes
A piece of physical volume, logical volume, and solid
Particle trajectories and tracking steps
Hits of particles in detector components
Other user defined objects can be visualized:
Polylines, such as coordinate axes
3D Markers, such as eye guides
Text, descriptive character strings, comments or titles
Scales
Logos
The many graphics systems that Geant4 supports are complementary to each other.
OpenGL
View directly from Geant4
Uses GL libraries that are already included on most Linux systems (plus some Windows availability)
Rendered, photorealistic image with some interactive features
zoom, rotate, translate
Fast response (can usually exploit full potential of graphics hardware)
Limited printing ability (pixel graphics, not vector graphics)
OpenInventor
View directly from Geant4
Requires addition of OpenInventor libraries (freely available for most Linux systems).
Rendered, photorealistic image
Many interactive features
zoom, rotate, translate
click to "see inside" opaque volumes
Fast response (can usually exploit full potential of graphics hardware)
Expanded printing ability (vector and pixel graphics)
HepRep/WIRED
Create a file to view in the WIRED3 HepRep Browser or the WIRED4 JAS Plugin
Requires WIRED browser (a Java application easily to install on all operating systems)
Wireframe or simple area fills (not photorealistic)
Many interactive features
zoom, rotate, translate
click to show attributes (momentum, etc.)
special projections (FishEye, etc.)
control visibility from hierarchical (tree) view of data
Hierarchical view of the geometry
Export to many vector graphic formats (PostScript, PDF, etc.)
DAWN
Create a file to view in the DAWN Renderer
Requires DAWN, available for all Linux and Windows systems.
Rendered, photorealistic image
No interactive features
Highest quality technical rendering - output to vector PostScript
VRML
Create a file to view in any VRML browser (some as web browser plug-ins).
Requires VRML browser (many different choices for different operating systems).
Rendered, photorealistic image with some interactive features
zoom, rotate, translate
Limited printing ability (pixel graphics, not vector graphics)
RayTracer
Create a jpeg file
Forms image by using Geant4's own tracking to follow photons through the detector
Can show geometry but not trajectories
Can render any geometry that Geant4 can handle (such as Boolean solids)
Supports shadows, transparency and mirrored surfaces
ASCIITree
Text dump of the geometry hierarchy
Not graphical
Control over level of detail to be dumped
Can calculate mass and volume of any hierarchy of volumes
Qt
View directly from Geant4
Uses GL libraries that are already included on most Linux systems (plus some Windows availability)
Rendered, photorealistic image with some interactive features
zoom, rotate, translate
Fast response (can usually exploit full potential of graphics hardware)
Expanded printing ability (vector and pixel graphics)
Could make movies
If you want very responsive photorealistic graphics (and have the OpenGL libraries installed)
OpenGL is a good solution (if you have the Motif extensions, this also gives GUI control)
If you want very responsive photorealistic graphics plus more interactivity (and have the Qt and OpenGL libraries installed)
Qt is a good solution and will also give you the GUI control
If you want very responsive photorealistic graphics plus more interactivity (and have the OpenInventor libraries installed)
OpenInventor is a good solution
If you want GUI control, want to be able to pick on items to inquire about them (identity, momentum, etc.), perhaps want to render to vector formats, and a wireframe look will do
HepRep/WIRED will meet your needs
If you want to render highest quality photorealistic images for use in a poster or a technical design report, and you can live without quick rotate and zoom
DAWN is the way to go
If you want to render to a 3D format that others can view in a variety of commodity browsers (including some web browser plug-ins)
VRML is the way to go
If you want to visualize a geometry that the other visualization drivers can't handle, or you need transparency or mirrors, and you don't need to visualize trajectories
RayTracer will do it
If you just want to quickly check the geometry hierarchy, or if you want to calculate the volume or mass of any geometry hierarchy
ASCIITree will meet your needs
You can also add your own visualization driver.
Geant4's visualization system is modular. By creating just three new classes, you can direct Geant4 information to your own visualization system.
Your Geant4 code stays basically the same no matter which driver you use.
Visualization is performed either with commands or from C++ code.
Some visualization drivers work directly from Geant4
OpenGL
Qt
OpenInventor
RayTracer
ASCIITree
For other visualization drivers, you first have Geant4 produce a file, and then you have that file rendered by another application (which may have GUI control)
HepRep/WIRED
DAWN
VRML
The following sections of this guide cover the details of Geant4 visualization:
Section 8.2 Adding Visualization to Your Executable
Section 8.3 The Visualization Drivers
Section 8.4 Controlling Visualization from Commands
Section 8.5 Controlling Visualization from Compiled Code
Section 8.6 Visualization Attributes
Section 8.7 Enhanced Trajectory Drawing
Section 8.9 Polylines, Markers and Text
Other useful references for Geant4 visualization outside of this user guide: