When you specify an instrument, it may be of great help if you
visualize resulting neutron trajectories of a simulation alongside with instrument components.
If the placement of modules has been done correctly, trajectories are to be seen on
their path from source to detectors. But if for example
The visualization is done in steps, you just press the "Trajectories" button in the GUI, which starts the following process:
We advise to restrict the number of trajectories - it will be overwhelming to see a million lines and your viewer might be very slow.
X3D is a modern format for virtual reality scenes.
With third party viewers
you may zoom in every detail of a generated scene.
Modules are drawn with transparent outer surfaces, and the scene has the outlook and
light effects known from virtual reality.
VITESS does not provide a virtual reality engine, but cooperates with an external
X3D viewer.
The instantreality player
of Fraunhofer IGD is available for all supported operating
systems, download it as a binary to be used without fee in a non-commercial version. Note that the latest 2.2 version may not be supported by older Linux systems like Ubuntu 10.04. Please install InstantPlayer 2.1 or older in case you don't have the latest OS.
If you select (Options / Helper applications) an external X3D viewer installed on your system, it will be used to
show the generated geometry file. If the default InstantPlayer is present on your
system, this default will be found and used.
The visualisation is implemented for the most important instrument components including guides, choppers, slits etc. These components are visualised by their actual shape and are displayed in distinctive colors, i.e. sources are blue, guides are yellow etc. All components are labelled. Neutron trajectories are visualised by red lines, which connect their interaction (reflection, scattering, absorption) points.
The interaction with the 3D scene is very flexible. In the beginning the scene is shown
with the source in the origin. In examine mode (key shortcut e) you may orient the scene
with the mouse, left button pressed. It's like touching and turning a virtual ball around
the origin. Use the mouse wheel to zoom in an out. Press the right mouse button and move the mouse to zoom in or out more gently. If you want to reset the origin to another module,
switch to mode "look at" (key shortcut l) and click at the module you are interested in. Please note that this does not work for lines illustrating the neutron trajectories.
After that switch back to mode examine. If you got lost, press R or r. If you press 'Space' an info screen appears, which in particular contains, among other information, the current position and the orientation of the camera. The camera position is in meters and is referreing to the origin at the source position. Select View --> Statistics --> Keyboard Mapping to get the complete list of all keyboard shortcuts.
When generating a X3D scene, VITESS looks for an option file. You may edit this file with
the GUI, Options / X3D options. With Unix, this file is ~/.x3dopt, for Windows it's
FILES\x3d.opt where VITESS has been installed.
When editing this file with the GUI, you may see what may be changed, and with what syntax.
You may restrict the scene to some bounds, change the color and transparency of scene objects,
and may switch off text annotation.