5. Light Fixture Calibration

This is the last remaining step you have to go through in order to establish a bond between PHOTON and the lighting console. So far copies of your lighting show files have been loaded into PHOTON and both devices are communicating through Art-Net.

You will now need to establish geometric correspondences between PHOTON and the grandMA so both devices will share a matching virtual space. This will allow you to transparently control moving lights through PHOTON and use the tracking data generated by Albion to build interactive fixture behavior.

5.1. Calibration Process

  1. In PHOTON, open the 3D Scene module by pressing [Alt+C] or by selecting {System > 3D Scene} if it is not already open.

  2. Select a moving light by clicking on the fixture in the Scene Primitives list (if you successfully completed the previous steps, all of you moving light should be listed).

  3. Select {Window > Device Control} or press [Q] to open the Device Control window. The moving light control stream mode should currently be set to “Output”. Select the control dropdown menu (third menu from the top of the Device Control window) and change the control stream mode to “Input”.

The previous step should be recorded as a cue in PHOTON in order to speed up the calibration process. (Cue X: group-select the lighting fixtures in the Scene Primitives list, press Q, set the menu to input.)

Make sure PHOTON is listening to the correct universe through its input. If the moving light’s address in the grandMA is different than the one in PHOTON, apply a Uni IN offset value to match both universe (can be negative). For example, if PHOTON listens to fixture channels on universe 14 and the grandMa is talking to the moving lights on universe 4, you will need to set a Uni IN offset of -10 to listen to fixture data sent by the grandMA.

  • Repeat the previous step with all of your moving head lighting fixtures. By selecting the “Input” control stream mode, PHOTON will transmit DMX commands sent by the lighting console to the lighting fixtures, giving a full control over all of their Attributes to the grandMA.

You can change the I/O Control mode on many fixtures at the same time by using the multiple selection. You can delete a fixture from the 3D scene and the I/O manager by clicking on Remove link fixture (multiple selection is supported).

  • Before moving on to the next step you will need a minimum of 4 active and identified Copernics in the stage space. Make sure you take note of the unique ID attributed to each of the Copernics you will use (the IDs are shown in the 3D Scene window) VYV recommends 5 or more Copernics to achieve better results.

  • Leave the media server and go back to the lighting console. Using its control interface, point all of the moving head lighting fixtures so that their beams converge on the position of the first Copernic you will use in the calibration process. To improve calibration results, make sure to use the narrowest beam the fixture can offer (you can use gobos or blades in addition to zoom and focus to get better results). Also, use the shadow created by the tracker when lights are pointing at it to help with alignment.

The lighting console operator should save position presets for his moving head lighting fixture group corresponding to each the Copernics position used during the calibration process. Having pre-programmed positions from the lighting console will greatly speed up the calibration since they will be easily recalled.

The lighting console operator has to flip some of the fixtures in order to improve the overall calibration. The fixtures for at least 2 of the 5 Copernics should be flipped. Refer to the Fixture Flipping entry in Section 5.2 Improving the Calibration for details.

  1. Once the beams of all the moving head fixtures point to the Copernic go back to PHOTON’s 3D Scene and pay attention to the Calibration tool window (lower right corner of the window).

  2. Make sure the moving head lighting fixtures you need to calibrate are selected (they should be highlighted in the list at the leftmost part of the Calibration tool window).

  3. Before resetting the calibration, create a new Calibration Preset (on all moving lights using + or 9 dots button and rename your new preset).

  4. Select the ALBION object in the Primitive List by clicking on it and click on the [compute reconstruction] button.

  5. Go back to the Calibration Tools Window and in your new preset, delete ALBION from the Reference Object list and add it one more time to update the reconstructed trackers position. Then select all the moving lights you want to calibrate in the primitive list, open properties and enable Lens shift.

  6. Click on the [Reset] button in the DMX section of the Calibration tool window to start a brand new calibration for the selected fixtures. Make sure that ALBION is used as the Reference Object and that target tracking is disabled.

The previous step should be recorded in a PHOTON cue. (Cue X: group-select the lighting fixtures in the Calibration Tools Window list > click on [Reset]).

  • Still in the DMX section set the Copernic ID with the slider. The number should match the one displayed near its representation in the 3D Scene. Click on the [Add Point] button.

The previous step will have to be repeated for each Copernic you will use in the Calibration process. You should record each of these action sequences in a PHOTON cue. (cue #1: group-select the lighting fixtures in the Calibration Tools Window list > set the Copernic #1 ID > click on [Add Point], cue #2: : group-select the lighting fixtures in the Calibration Tools Window list > set the Copernic #2 ID > click on [Add Point], etc.).

  • To enable tracking, turn your moving lights into output mode and enable target tracking in the device control menu (Q) of the fixture from the Primitives list.

5.2. Improving The Calibration

Quantity and Dispersion

If you followed the previous instructions, your system should be calibrated. You might however notice a lack of precision while positioning the moving head lighting fixtures. You can improve your results by:

  • Selecting Copernics with a good distribution in the 3D physical space. Copernics should be scattered to cover the whole stage area where light beams will be projected.

  • Copernics should also be evenly distributed from the point of view of all your fixtures. You can verify this by selecting one by one each of your fixtures in the Calibration Tool window list (leftmost part of the window). Whenever you select a fixture, you will be able to “see” the distribution of the Copernics from its point of view. You avoid situations where Copernics are concentrated in a single area of the POV.

  • Adding additional Copernics will improve the final results. While 4 Copernics represent the minimal amount of markers needed for the calibration process, you should consider using between 5 and 7 to achieve better results.

Fixture Flipping

Fixture Flipping consists in applying a 180 degrees rotation to the Pan value and inverting (*-1) the Tilt value of the fixtures while maintaining their light beam position. You should calibrate the lighting fixtures with the first half of the Copernics normally and flip the fixtures to calibrate remaining ones.

How to perform a “fixture flipped” calibration:

  1. Before starting the calibration, go to PHOTON’s 3D Scene and select the first moving lighting fixture in the list.

  2. Press [P] or select {Window > Properties} to open the fixture’s Properties window.

  3. Activate the “Lens Shift Option” in the Properties window.

  4. Calibrate your system with the first half of your Copernics normally.

  5. The fixtures will now be ready to be flipped from the light console (ideally, the light board programmer should have created a ‘’flipped’’ position preset).

  6. Calibrate the system using the remaining half of the Copernics.

  7. If the results are still poor, try to change the “clockwise panning” option of the moving light and update the calibration by selecting a calibration point and moving it back and forth using left/right arrows.

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