VisTrak Vcam B
Vertical launch and ball spin detection
3 camera system: Single overhead mounted camera (VisTrak Eagle)
plus dual vertical launch angle detection cameras with ball spin detection
In order to use regular balls with the Vcam B, the unit has to be placed near the player otherwise
( due to spin axis ) the logo on the ball will - in all likelihood - rotate out of view.
When the unit is placed further away, spin dot balls - that feature printed dots all around the ball - are required
The Vcam B is the same as a Vcam plus Spin cam but mounted in a carry case
It is used with the ceiling mounted VisTrak Eagle to detect vertical launch angle and ball spin rate.
Vcam B ball spin detection using hi resolution ball images
Ball spin and vertical launch
Add-on to the VisTrak Eagle
Vcam B images
when Vcam B is mounted near to the player
The above shows real balls - viewed from the side - with a back spin rotation and rotation axis shift.
Regular balls with a logo
Regular balls with either a black logo or line can be used with the Vcam B when the unit is placed near the player.
Spin dot balls
Special spin dot pattern balls are used when the unit is placed further away from the player.
These balls also save the player from having to bend down and line up the ball logo or line to the cameras.
VisTrak: Multiple camera setups
The VisTrak Vcam B is using 3 cameras:
1. The ceiling mounted hi-speed VisTrak camera
2. Two hi-resolution ball spin and vertical launch angle detection cameras.
When the system is functioning correctly, all status blocks of the cameras shown in the Control Panel's main window will turn from red to green
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 B are:
Cams 1 and 2 are the Hi Res ball spin cameras and Cam 3 is the VisTrak camera.
To check for correct camera assignments for the VisTrak Vcam B,
go to the cameras window in the CP and successfully click on the cameras 1, 2 and 3.
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.
Auto camera assignments
This new feature eliminates the need to manually assign the cameras
Simply switch on the Auto Camera Assigns option and restart the CP.
Vcam B Setup
Measuring ball spin using the ball's logo.
The Vcam B captures 3 frames with the two floor mounted cameras.
Frame 1: the ball at launch position (captured when the VisTrak camera detects a ball on the mat).
Frame 2: the ball in flight after the trigger delay
Frame 3: the ball in flight after the base trigger delay plus an additional Cam1 to Cam2 delay
Cam 1 to Cam 2 trigger delay
The trigger delay difference between camera 1 and camera 2 is used to calculate the ball spin
It is set independently from the base trigger.
Both cameras have the same base trigger delay - in order that the ball in flight is captured in the FOV of the cameras - but camera 2 has this additional delay added to it.
This difference in trigger delay time is used as the time taken for the ball to rotate in the ball spin images and directly effects the spin calculations.
Most will probably not want to use specially marked balls so we have developed the Bcam system to use the standard ball logo on the ball to measure ball spin and spin axis.
There are a number of new options for the VisTrak Vcam B system in the Setup window:
1. You have the option to use a line scan camera top trigger the Vcam an Spin cameras.
If this option is not ON then the trigger signal will come from the VisTrak camera which requires a trigger delay setting.
2. You can now manually set the launch position for the Vcam camera instead of the system auto detecting the ball on the mat.
This is done because the ball on the mat may not always be in the FOV of the Vcam.
3. if not using a Line Scan camera, then the trigger can either be via a Soft Trigger instruction to the Vcam and Spin cameras or via a GPIO trigger line
Default is soft trigger.
Trigger frame and trigger delays
The Vcam B is 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 before the FOV of the camera and if fired too late
the ball images will be beyond the FOV of the Vcam B cameras.
Trigger delay options for VisTrak Stereo or Vcam systems
There are two methods of setting the camera trigger delays:
1. a single global trigger delay setting for all shots and clubs
2. a club depedent trigger delay that changes the delay when a new club is selected or used
You can switch the club dependent Vcam or Stereo camera trigger delays on or off from the CP's main window.
Note: this feature is as of CP version 220.127.116.11 Beta
If off, then the regular Vcam trigger delay - as displayed in the Vcam window - will be used.
You may have to experiment a bit to find the ideal trigger delay so that the ball in-flight is in the FOV of the cameras for all shot speeds.
A trigger delay of around 10 ms should be good though.
Club dependent Trigger delays for VisTrak Stereo and VisTrak Vcam
To set club trigger delays:
1. click on the club image to select the club
2. use the +/- red and green butons to set the trigger delay for the selected club.
3. repeat the procedure for all clubs.
4. Finally, switch the "Club Trigger Delays" option ON
If the trigger delay is too short, then the ball will be too near to the club for the cameras to detect it correctly.
Trigger delays can also be automatically set depending on how close the ball is to the pin during a game.
Minimum ball speed for VisTrak Vcam.
If the measured ball speed from the VisTrak Eagle is less than this user defined minimum speed,
then data from the Vcam camera will be ignored
and all launch data will be derived from the VisTrak Eagle.
This is done because data from the Vcam camera with small chips cannot be guaranteed to be correct
due to either the ball being too close to the club or the ball trajectory is already on the downwards path by the time the cameras capture the ball images
and thus the measured vertical launch angle will not be correct.
Use the left/right arrows keys to adjust the min speed for Vcam when selected.
Use the up/down arrow keys for overall min ball speed.
Thusly, the trigger signal has to be delayed somewhat but not be delayed too much.
Some experimentation will be required to get the settings just right.
... more instructions to follow