Section 6: Calibration and Virtual Camera Control

This section describes how to calibrate ARwall ARFX using the patented XR Sync system and describes how to use the ARwall camera controls once ARFX is up and running.

Section 6.1: XR Sync Calibration

This section describes how to calibrate ARwall ARFX using the patented XR Sync system. This process is the same whether running ARFX through the ARFX Launcher or through Unreal Engine 4/5. 

Once the ARwall ARFX scene is up and running, calibrate the scene so that the proportions and parallax looks correct to the tracked physical camera. To perform calibration in ARwall ARFX, do following: 

1. Press the TAB key on a keyboard or X button on an Xbox controller, the calibration screen will open. Locate the center of the screen marked by the red crosshairs.
   
2. The green triangle/square that appears represents the calibration tracker. The current position is always relative to the last calibration point but should always move in relationship to wherever you move the calibration puck.
   
   NOTE: The green triangle/square should move when moving one of the trackers connected to the system. This is the tracker previously set as the calibration tracker. If this is not the intended tracker for calibration, either swap the trackers physical positions (on the camera vs next to the screen) or swap the serial numbers. Further information on how to obtain the serial numbers can be found here: Section 3.6 Identify and Label Vive Tracker Serial Numbers via USBDeview  
   
   
3. Place the calibration puck flat against the screen and centered on the crosshairs with the green light on the tracker facing up (for 2.0 Trackers) and with the green light on the tracker facing down (for 3.0 Trackers). Both 2.0 and 3.0 Trackers will have the cable pointed up for correct calibration. Press the Calibration button (that was set previously under Hotkeys, by default it should be the C key on keyboard and B button on Xbox controller) while the calibration puck is on the crosshairs, then press TAB (or whichever button was previously set under Hotkeys) to exit the calibration screen.
   
   2.0 Trackers
   
   3.0 Trackers
   
   BEST PRACTICE: Feel free to press the Calibration button again if it does not look like it calibrated correctly the first time. Make sure the calibration tracker is positioned in place on the red crosshairs, until it looks like the ARFX Screen looks correctly positioned and does not jump around a lot between calibration button presses. This ensures that you have the most optimal calibration.
   
   NOTE: It is good practice to recalibrate anytime a lighthouse is moved or bumped, even if very minute. This could cause jitter/jumping of the virtual camera if not recalibrated.
    
4. If calibrating for a multiscreen version of ARFX Pro Plugin, the crosshairs will be green (instead of red) and the box representing the calibration puck will be a red box with a plus sign in the middle. Otherwise, calibration should be the same for multiscreen. 

Section 6.2: Calibration Puck Tracker Offset Setup

If for any reason the calibration puck cannot be physically placed on the center of the screen during the calibration process, it’s possible to add an offset for calibration so that calibration puck can be placed somewhere more accessible. The Screen Offset function allows you to change the settings inside Unreal Engine 4/5 to match the physical distance where the center of the physical screen is and where the calibration puck may need to be on set. 

NOTE: During calibration mode, the bottom of the calibration tracker needs to be pointed at the screen, placed flat vertically on the center of the screen where the red crosshairs show. When using an offset location for the calibration puck, make sure to keep the bottom of the tracker still pointing towards the physical screen. This may require a ¼ inch screw set up that keeps the puck in that same 90 degree rotation.

1. Set up calibration tracker offset to match in Unreal Engine. 
   1. Match the virtual ARwall Camera Actoroffset to match the physical camera hero tracker offset.
      1. Measure the vertical (up/down, Z-axis), depth (forward/backward, X-axis), and side to side (left/right, y-axis distance in centimeters from the center of the red crosshairs from the screen while in calibration mode to the bottom/center of the physical Vive calibration tracker.
         
         BEST PRACTICE:  It is recommended to place your offset calibration tracker in a position that is precise, still, and unmoving. 
         
         
      2. Follow the examples displayed in the image below to offset correctly. Left offsets negatively, right offsets positively.
         
      3. Input the X, Y, and Z-axis values determined from physical measurements into Details > ARwallCameraActor > ARwall > Screen Offset > Location’s X, Y, and Z-axes.
         

Section 6.3: Virtual Camera Control

This section describes how to use the ARwall camera controls for both keyboard and Xbox controller once the ARFX Pro Plugin is launched and calibrated. 

1. Play ARFX Pro Plugin scene within Unreal Engine 4/5 and calibrate. Refer to Section 5: ARwall Setup and Settings within Unreal Engine 4/5 and Section 6.1: XR Sync Calibration for further details. 
2. Move the Hero Tracker (tracker on the physical camera) within the designated play area as dictated by the base stations. The scene should show the correct parallax. 

BEST PRACTICE: Here is how to tell if you are seeing the correct parallax after calibration: 

• Move the physical camera left, you should see more of the right side of the virtual scene environment.  
• Move the physical camera right, you should see more of the left side of the virtual scene environment. 
• Move the physical camera up, you should see more of the bottom of the virtual scene environment. 
• Move the physical camera down, you should see more of the top of the virtual scene environment. 
• Move the physical camera closer to the screen, you should see more of the virtual scene environment. 
• Move further from the screen, you should see less of the environment.  

If this is not what you’re seeing, try to calibrate again and make sure that the base stations can clearly see each other and the trackers. Refer to Section 3.4 Base Station Placement for further details. 

The default virtual camera controls are described in Table 4 below.

Table 4: Virtual Camera Controls

Refer to the keyboard hotkeys online here: http://www.keyboard-layout-editor.com/#/gists/98cd82217ffe1eb61fc7a6ae19d97862

Section 6.4: Input Scale

This section describes how to adjust the movement speed of the ARwall camera controls for both keyboard and Xbox controller once the ARFX Pro Plugin is launched and calibrated. 

1. If the arrow keys described in Table 4 above, which are used to rotate/pan the camera left or right, are not working, verify whether the four Input Scale options (Input Yaw Scale, Input Pitch Scale, Input Roll Scale, and Input Scale) inside the ARwall Camera match or have a value higher than 0 as displayed in Figure 5 below.
   
   Figure 5: ARwall Inputs
   
2. If moving the virtual camera is too slow or too fast while using WASD or the XBOX Controller left stick, adjusting Input Scale higher or lower will adjust this speed. 
   1. For instance, if a map is very large in scale, a higher Input Scale value (around 10-50) will help traverse the map more quickly. Conversely, if the Input Scale value is too high on a smaller map, lowering the value to 5-10 might be preferable.
       

Section 6.5: Near Clipping Distance

This section describes how to adjust Near Clipping Distance of the ARwall camera once the ARFX Pro Plugin is launched and calibrated to remove unnecessary planes that block the virtual camera view. Near Clipping Distance is great for tight shots when a virtual plane or object is blocking the virtual camera view.

1. If composing a shot and the virtual camera is being blocked or is clipping through a surface or object, use Near Clipping Distance to “clip away” the virtual surface/object to unblock the virtual camera view. While in play mode, this can be adjusted in one of two ways:
   1. In Unreal Engine:
      1. Navigate to ARwall Camera Actor > Details > ARwall > Near Clipping Distance.
      2. Adjust the value to see the blocking virtual plane disappear/reappear.
         
   2. In ARwall Options Menu:
      1. Press Backslash on the keyboard to toggle on the ARFX Options Menu and navigate to ARFX > ARFX Camera Options > Near Clip Distance. 
      2. Adjust the value to see the blocking virtual plane disappear/reappear.
         NOTE: A higher Near Clipping Distance value will make anything near that distance to the virtual camera disappear. Readjust to a lower value if too many objects/surfaces disappear.