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Powerwall Configuration

What is a powerwall ?

A powerwall is a large, ultra-high-resolution display which displays stereoscopic 3D images. Coupled with a tracking system, it provide an immersive virtual reality experience.


ART DTrack

DTrack is the software provided with ART tracking captors. It will record and transmit the data of your tracked devices.


VRPN is an interface which can recieve data from a software and expose it to another.

NDisplay Launcher

Ndisplay is an UE4 plugin which allows you to start your project on several PC arranged in cluster. It is also working for a cluster of only one device.

The NDisplay documentation can be found here.

To be able to run Skyreal in Powerwall mode, it must be started with the NDisplay Launcher.

It can be found in the UE4 directory :

C:\Program Files\Epic Games\UE_4.20\Engine\Binaries\DotNET\nDisplayLauncher.exe

Interaction Device

To be able to interact in Skyreal set in Powerwall mode, interaction devices are needed. They must be trackable by the ART captors and preset buttons to do actions in Skyreal (navigate, use commands …).

We recommend you to use the VenomX device which has enough buttons and on which reflective balls can be added to make the device trackable.


DTrack Configuration

Room Calibration

Go to Calibration, then Room.

Hit Calibrate button.

Go to Calibration, then Room adjustment.

Make sure the axis are Up : Z, Forward : Y, Right : X.

Bodies Calibration

Go to Settings, then Body administration.

Increase the number of body to the needed number.

Go to Calibration, then Body.

Make sure the coordinate system is set to “due to room” and hit Calibrate button.

You can try to recognize your body (Target Library), or calibrate it directly (Custom).

You can then rename your bodies in the Body Administration window.

The devices expected by Skyreal are 1 Head Tracker, 1 Right Hand Tracker, and 1 optional Left Hand Tracker. These trackers need to be ordered like this (Head first, then Right Hand and then Left Hand).


Go to Settings, then Output.

Define the UDP port to 5000.

VRPN Configuration

Config file

In the config file “vrpn.cfg”, the used port need to be defined, by default it is 5000.

In VRPN, the VenomX is managed as a keyboard. And so, if a VenomX is used, a vrpn_Keyboard must be added too.

# start vrpn test for DTrack
vrpn_Tracker_DTrack DTrack  5000
vrpn_Keyboard Keyboard

The StartServer.bat (located in the VRPN directory) launchs the VRPN server.

The StartTest.bat (located in the VRPN directory) allows you to see which data are received by the server.

NDisplay Configuration File

The “configPowerwall.cfg” contains the configuration of the VR space and devices for NDisplay.

Not all settings must be redefined for the standard use of Skyreal but for a more precise description of this file please refer to the NDisplay documenation.


The IP address of the cluster_node must be redefined. Use the address of the test PC.

[cluster_node] id=node_1 addr= screen=screen_1 viewport=vp_1080 port_cs=41001 port_ss=41002 master=true sound=true


The size of the screen must be redefined.

[screen] id=screen_1 loc="X=0,Y=0,Z=0" rot="P=0,Y=0,R=0" size="X=1.435,Y=0.85" parent=display_1


The standard line need no modification.

[viewport] id=vp_1080 x=0 y=0 width=1920 height=1080 flip_h=False flip_v=False


The standard line need no modification.

[camera] id=camera_static loc="X=0,Y=0,Z=0" parent=camera_node


You need to redefine the locations of the nodes.

  • The Z component of cave_origin
  • All the components of display_1 (center of the screen) : X is the distance between the screen and the origin, Z is the distance between the floor and the center of the screen
[scene_node] id=cave_origin loc="X=0,Y=0,Z=-0.043" rot="P=0,Y=0,R=0"
[scene_node] id=display_1 loc="X=2.435,Y=0.12,Z=1.485" rot="P=0,Y=0,R=0" parent=cave_origin
[scene_node] id=camera_node loc="X=0,Y=0,Z=0" rot="P=0,Y=0,R=0" tracker_id=SkrTrackers tracker_ch=0


The Z component of the location may need to be redefined.

In this example, Z=-0,043 because the room calibration tool used was 0,043 m high.

[input] id=SkrDevice type=buttons addr=Keyboard0@ remap="255:30,254:44,253:18,252:19,251:16,250:31,249:32,248:33,247:21,246:22,245:23,244:24,243:35,242:36,241:37,240:38"
[input] id=SkrTrackers type=tracker addr=DTrack@ loc="X=0,Y=0,Z=-0.043" rot="P=0,Y=0,R=0" front=Y right=X up=Z parent=cave_origin


The standard line need no modification.

[stereo] eye_swap=False eye_dist=0.064


The standard line need no modification.

[general] swap_sync_policy=0

NDisplay Launcher

Start the NDisplay Launcher.

Add and select the project (1) and add and select the config file (2).

Starting 1.7, Sky Real support command line arguments for the powerwall, enabling  easier configuration of the base parameter. The following parameter are supported :

  • to configure the license options
    • -Local=”xxxx” : True if the license if on the computer where SkyReal is run, False if  there is a license server
    • -IpServer=””: the ip adress of the license server
    • -PortServer=”xxxx”: the port of the license server
    • -Type=”xxxx” : the type of licence (Full or Trial)
  • to configure the collaborative options :
    • -IsCollab=”xxxx”: Determine if the session will be collaborative (true) or not (false)
    • -IsServer=”xxxx”: Set this session as the server for the collaborative session
    • -Alias=”xxxx”: Set the alias of the user for the collaborative session
    • -CollabServerAdress=”xxx” : the server adress
  • to load immediately a map :
    • -Simulation=”xxx” : Path to load the map

In case some option are absent, the default option will be used.

Also the selection of a file go through the window selection picker.


Input Configuration

The VenomX inputs can be mapped with a dedicated software which can be downloaded here.

To reassign inputs, go to the PC tab and click on the button to remap. Hit then the new key. When 2 VenomX are used, one of them must be disconnected to configure the other.

Remaping in the NDisplay config file

In VRPN, the VenomX is managed as a keyboard. Each key pressed will send a “pressed” event with a specific scane code corresponding to that key.

To let users be able to freely choose which key they want to use, Skyreal use standard scan codes to map the possible actions :

255 Right MenuButton
254 Right ActionButton
253 Right MoveForwardButton
252 Right MoveBackwardButton
251 Right StrafeRightButton
250 Right StrafeLeftButton
249 Right IncreaseSpeedButton
248 Right DecreaseSpeedButton

247 Left MenuButton
246 Left ActionButton
245 Left MoveForwardButton
244 Left MoveBackwardButton
243 Left StrafeRightButton
242 Left StrafeLeftButton
241 Left IncreaseSpeedButton
240 Left DecreaseSpeedButton

Users have to remap their used scan codes to the standard codes of Skyreal.

To know what is the scan code corresponding to the key pressed we recommend to use the script StartTest.bat in the VRPN directory. This script will display the scan codes of the pressed keys.

When the codes are known, they must be remaped in the NDisplay config file :

[input] id=SkrDevice type=buttons addr=Keyboard0@ remap="255:30,254:44,253:18,252:19,251:16,250:31,249:32,248:33,247:21,246:22,245:23,244:24,243:35,242:36,241:37,240:38"


You setup should now be correct

  • Start the Dtrack record
  • Start the VRPN server
  • Start the NDisplay launcher
  • Hit the start listeners button
  • Hit the run button

Skyreal should start on your powerwall and your trackers should be tracked

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