Fixture Calibration Steps

Zhongtian Wang
19 steps
2 minutes

Fixture calibration is a function intended to improve the tracking accuracy of lighting fixtures. The information imported from BTwyg places the fixture in an approximate position in the virtual world. However, there are often minor discrepancies between real life and a CAD drawing. For example, the hanging structure might be angled by a few degrees, or the fixture may not be hung perfectly square. Fixture calibration allows you to correct these discrepancies and ensures the location of fixtures is accurate. It is recommended that all fixtures be calibrated when they are first installed in the space, moved/bumped, or when the ground plane location is moved.

Please check that all fixtures that will be used for tracking have been imported into BlackTrax.

Ensure the beacon used to perform fixture calibration is in the beacon list.

When using a Mini Beacon for fixture calibration, ensure the Mini Beacon's ID is set to 1 before proceeding. This can be done in Device Manager.

Click on "Calibration View"

Click on "Fixture Calibration"

Change the mode from "Normal Mode" to "Fixture Calibration."

In Fixture Calibration mode, BlackTrax takes control of extra parameters like zoom, iris, color, gobo, and prism, and clears all creative effects from the fixture to simplify the calibration process. **Fixture calibration must be turned off during normal operation of the system.**

Select a fixture you want to calibrate

Click on "Assign Beacon"

To perform a Fixture Calibration, the stringer must be connected to port 1 of the Classic Beacon.

Select the beacon that will be used for the fixture calibration. If a stringer is plugged into port 1 of the beacon; the X/Y/Z values will provide constantly updating tracking information.

If using a Mini Beacon to perform fixture calibration, select Beacon 1.

Click "OK"

During fixture calibration, the software will use the collected five (or more) samples to calculate a new position that is more accurate to the real-world space, providing better tracking results.

The fixture should then start to track the stringer. If the pan/tilt of the fixture is reversed, this can be changed in BTWyg (Follow fixture patch guide). As shown in the picture, the beam of the fixture is off-center from the stringer.

To collect a data point for fixture calibration, press button A on the beacon. (If using a Mini Beacon, the "Freeze Beam" button in the software functions the same way.) When the beam is frozen, the fixture will not pan or tilt, so the beam will stay in place.

If working in a large space, using the lighting wand in our Calibration Kit can help with the following process.

Move the stringer so that it is at the center of the beam. (Anywhere along the path of the beam, so long as it is centered)

Press button B on the beacon to collect a data point. (Or the "Collect Data Point" button in the software) Upon pressing the button, the fixture will perform a pan-flip and then continue to track the stringer.

Five data points are required for calibrating a fixture. The more varied samples taken, the better the calibration will be. An easy way to collect varied samples is to take samples at each of the four corners of the tracking space and once in the center. Adjust as needed based on the shape and size of the performance venue.

After taking 5 points, BlackTrax will automatically calculate and apply the calibration. The fixture should then be tracking much more accurately. To assess the calibration, walk around the space with the fixture following, and check if the beam is consistently centered. Add samples in any area where calibration is poor. If the tracking is generally poor, delete all samples and redo a full fixture calibration. Samples can be deleted by clicking on the "Delete Points" button.

If a fixture is not tracking accurately after calibration, the Fixture Calibration Points widget can be consulted to find any points that may be causing problems. The Residual represents the amount of error caused by the point. All points will have some residual error. In this case, lower numbers are better, so looking for the highest number can be an easy way to find the point(s) which are contributing bad data. Generally, a residual of below 0.1 is a good sign. Deleting any points above 0.1 will typically improve the calibration results. Note that when deleting any point, the residual values of all points on the fixture will be re-calculated. If deleting a point leaves the fixture with fewer than 5 points, it will revert to it's uncalibrated state, until a 5th point is collected again. Once this has been completed, re-confirm the tracking accuracy. Repeat as needed. Please keep in mind that if a fixture is tracking satisfactorily, it is unnecessary to check these values. This is only helpful when tracking results need to be improved.

After finishing calibrating a fixture, unassign the beacon so it can be used on other fixtures.

Multiple fixture calibration can be performed by selecting a group of fixtures need to be calibrated, and assign a beacon to them.

When calibrating multiple fixtures at the same time, all selected fixtures will track the stringer. However, only the fixture with its brightness up is actively being calibrated; all others will be doused. The process collects the first data point for all fixtures before moving on to the second point, and so on, until all five points have been collected for all fixtures.

Follow step 10 - 13 to collect the first data point for the first fixture. Upon pressing button B on the beacon, the first fixture will douse and then perform a pan-flip, and the next fixture will automatically turn on. Proceed to collect the first data point for each remaining fixture, repeating the process until all fixtures have their first data point collected.

After collecting the first data point for all fixtures, move to the location where the second data point is planned to be collected. Continue collecting data points in this manner for all five points

It is often easier to select fixtures that are in the same general area to group together for calibration. Selecting fixtures from opposite sides of the room often requires much more walking, and reduces the time saving of calibrating multiple fixtures at once.

Once the fixture calibration is finished, change the mode back to Normal Mode.