ParaView/Users Guide/CAVE Display

Introduction

• ParaView has basic support for visualization in CAVE like environments. These environments consists of multiple displays which are configured based on some coordinates in the room. Typically the base coordiante of the room is the reference coordinate of the head-tracker.

• ParaView can operate in a Client-Server fashion. The CAVE modules leverages this by assigning different process on the server to manage different displays. The client acts as a central point of control, sending tracking values to each of the processes on the server.

• ParaView has a VRPN (Virtual Reality Private Network) client plugin which reads tracked information from any VRPN server and relays the value to each process managing the display.

• Displays are configured using the PVX configuration XML file.

Prerequisites

• VRPN needs to be installed on the client side.
• MPI needs to be installed on the server side.

• Make sure to enable BUILD_SHARED_LIB, PARAVIEW_USE_MPI and PARAVIEW_BUILD_PLUGIN_VRPNPlugin when building for CAVE support.

• Consequently VRPN_INCLUDE_DIR and VRPN_LIBRARY should also be set.

Structure of config file

<source lang="xml"> <?xml version="1.0" ?> <pvx>

 <Process Type="server|dataserver|renderserver">
   <Machine name="hostname"
            Environment="DISPLAY=m1:0"
            LowerLeft="-1.0 -1.0 -1.0"
            LowerRight="1.0 -1.0 -1.0"
            UpperRight="1.0  1.0 -1.0">
   </Machine>
 </Process>

</pvx> </source>

Example Config

• The following example is for a six sided cave with origin at (0,0,0).

<source lang="xml"> <?xml version="1.0" ?> <pvx>

<Process Type="client" />
<Process Type="server">
 <Machine Name="Front"
          Environment="DISPLAY=:0"
          LowerLeft=" -1 -1 -1"
          LowerRight=" 1 -1 -1"
          UpperRight=" 1  1 -1" />
 <Machine Name="Right"
          Environment="DISPLAY=:0"
          LowerLeft="  1 -1 -1"
          LowerRight=" 1 -1  1"
          UpperRight=" 1  1  1" />
 <Machine Name="Left"
          Environment="DISPLAY=:0"
          LowerLeft=" -1 -1  1"
          LowerRight="-1 -1 -1"
          UpperRight="-1  1 -1"/>
 <Machine Name="Top"
          Environment="DISPLAY=:0"
          LowerLeft=" -1  1 -1"
          LowerRight=" 1  1 -1"
          UpperRight=" 1  1  1"/>
 <Machine Name="Bottom"
          Environment="DISPLAY=:0"
          LowerLeft=" -1 -1  1"
          LowerRight=" 1 -1  1"
          UpperRight=" 1 -1 -1"/>
 <Machine Name="Back"
          Environment="DISPLAY=:0"
          LowerLeft="  1 -1  1"
          LowerRight="-1 -1  1"
          UpperRight="-1  1  1"/>
 </Process>

</pvx> </source>

• A sample PVX is provided in ParaView/Documentation/cave.pvx. This can be used to play with different display configurations.

Things to keep in mind

• pvx file should be specified as the last command line argument for any of the server processes.
• Typically the pvx file is specified for all the executables whose environment is being changed using the pvx file. In case of data-server/render-server configuration, if you are setting up the environment for the two processes groups, then the pvx file must be passed as a command line option to both the executables: pvdataserver and pvrenderserver.
• When running in parallel the file is read on all nodes, hence must be present on all nodes.

Basic steps for a successful setup

• On a terminal run the server (6 processes each driving one display in the cave. Change the number of process according to the number of displays).

 # PV_ICET_WINDOW_BORDERS=1 mpiexec -np 6 ./pvserver  /path/to/ConfigFile.pvx

Note: PV_ICET_WINDOW_BORDERS=1 disables the full screen and instead opens up a 400x400 window. Remove this environment variable to work in full screen mode

• Open another terminal to run the client. (note: this client connects to the server which open up 6 windows according to the config given in cave.pvx). Change the stereo-type according to preference (see # ./paraview --help).

 # ./paraview --stereo --stereo-type=Anaglyph --server=localhost --vrpn --vrpn-address=Tracker0@localhost

• Connect the client to the server.

• Enable the VRPN Plugin on client.