VisTrak Vcam Setup
The VisTrak Vcam's main purpose is to detect the vertical launch angle of the ball when used with the VisTrak Eagle.
In our CX2 systems the Vcam is also used to measure ball speed by measuring the length of the ball trace
but when used with the VisTrak Eagle, it's only used to measure vertical launch angle.
i.e. it's not imperative that the full length of a ball trace is detected. Just any part of the trace will suffice.
Note that the super bright green LED on the Vcam is the same "looking for ball" and "ball detected" indicator as on the ceiling mounted VisTrak Eagle.
As the Vcam cam is floor mounted, this indicator will be more visible to the player.
The Vcam, together with its two IR LED lights, are mounted on a single base platform.
1. Place the VisTrak Vcam camera and IR LED lights around 3 ft or 4 feet ahead of the ball strike zone
on either the left or right hand side of the enclosure.
2. Connect the Vcam camera USB 2 cable to a port on the PC
The Vcam vertical launch angle camera views the ball from the side and - due to its long exposure time -
the image of the ball is a white trace.
The camera field of view is actually far greater than what is actually required
and captures the player (on the right), the projection screen (on the left) and the floor.
The blue border lines dictate the valid field of view - i.e. the area where the system will be looking for the ball -
and the red line dictates the maximum ball height a ball will have to be considered as a rolling ball or sculled shot.
Note that the length of the ball trace is directly proportional to the ball's speed
and providing the camera's exposure time (10 milli seconds here) and the pixel to cm scale (0.2 here) is constant - which it always is - this correlation is constant and consistent.
i.e. no matter what the launch angle is, the length of the ball trace will always be the same for a given ball speed and will always be directly proportional to the ball's speed .
Note the strong contrast between the background and the ball trace.
This is achieved by setting the camera gain high which amplifies the contrast.
The ball is illuminated by the overhead and / or side mounted IR LED lamps.
Vcam B trigger frame and trigger delays
The Vcam B cameras are triggered to capture 2 freeze frames from the VisTrak Eagle camera.
It is important to set the timing of this trigger signal so that the Vcam B ball images are within the FOV of the Vcam B cameras.
If the trigger signal is fired too soon then the ball images will be captured before the FOV of the camera and if fired too late
the ball images will be beyond the FOV of the Vcam B cameras.
Thusly, the trigger signal has to be delayed somewhat but not be delayed too much.
There are two methods of delaying the Vcam trigger signal from the VisTrak Eagle:
1. Setting the trigger frame beyond the frame strike frame of 16
2. Setting a Vcam trigger delay in the Vcam camera window.
Both have the same effect.
Until we come up with recommended delay and camera trigger frame setting,
some experimentation will be required to get the settings just right.
You can now set which frame is used to trigger the add-on cameras (Vcam, Stereo, VcamB, HiRes).
The ball/club strike Frame is always frame 16. If "camera Trigger Frame" is also set to 16, then the add-on cameras will trigger immediately on ball/club contact.
If set to 32, the trigger will be sent after the video capture is completed. If set to 24, the cameras will trigger 8 frames after the initial ball strike frame.
The object here is to set a trigger delay that allows the ball to be within the FOV of the Vcam or Stereo cameras.
If set too low, the ball will only be seen at initial impact in the Vcam. If set too high, fast balls will be out of the FOV of the Vcam.
Note that the Camera Trigger Frame setting is in the "Adjust speed / carry distance" window.
The two main windows are the VisTrak Video window and the Camera window.
The VisTrak window is used to view the swing playback.
The camera windows are used to adjust camera settings like gain and shutter speed
When VisTrak Vcam is selected, camera 1 in the Cameras window becomes the Vcam and camera 2 the VisTrak camera.
It is essential that the correct camera assignments are made.
An error message is displayed if any of the cameras are incorrectly assigned.
Correct camera assignments for the VisTrak Vcam are:
Cams 1 is the Vcam and Cam 2 is the VisTrak camera.
To check for correct camera assignments for the VisTrak Vcam ,
go to the cameras window in the CP and successfully click on the cameras 1 and 2.
If one of the these cameras is incorrectly assigned, a large error message will be shown.
If you find that cameras are not being assigned in the correct order then you can manually re-assign the cameras.
To do this, select the camera in the CP cameras window, hold both the shift and ctrl keys down,
and press the left or right arrow keys to move the camera up or down the sequence.
Ensure that the "Fixed Assigns" option in the camera 1 window is OFF when re-assigning camera functions.
When assignemnt adjustments are completed, switch this option back ON so that the camera assignements are stored.
... more instructions to follow