Setting Camera Offset
The coordinate origin of the Intersense is the center of the back of the camera. To set the virtual imaging plane to match that of the physical film or video camera, an offset needs to be added.
The Tracker to Camera Offset tab provides this adjustment. The offsets are measured from the tracker (in this case the Intersense) origin to the center of the camera’s imaging plane. Most cinema type cameras will have a mark on the camera body to show where this is.
The axis sign orientation is:
- Axial: + goes towards the front of the camera
- Vertical: + moves upward
- Laterial: + goes toward the right of the camera, facing the same direction as the camera lens
Use Observer View to verify that the offsets are going the correct direction.
Aligning Angular Offsets
To correct for the small angular misalignments between tracker and camera:
Load the FBX file that correlates to the Intersense fidicual locations of the stage. Instructions for generating this file are here.
Check that the right lens calibration file is selected, the zoom and focus are correctly lined up, and that the correct sensor size is selected.
Deselect the Airtrack, so that the tracking is Intersense-only.
Rotate the Intersense camera to 45 degrees from horizontal, and adjust the Intersense configuration panel’s pitch setting to 45 degrees.
Point the camera up toward the ceiling so that the fiducials are in view of the camera.
Set all of the Coordinate System offsets to 0. (The Tracker to Camera offsets should be the normal distance from the Intersense to the camera sensor.)
The fiducials should line up pretty closely to the CG cones.
If they are offset, adjust the Tracker to Camera Offset panel’s Pan and Tilt settings to line them up. Note – this should be a small number of degrees; around 2-3 degrees in the Pan, and less than a degree in the Tilt. If it takes more than a degree in Tilt, look at the mounting bracket to make sure it is seated on the matte box rails, at a right angle to the matte box rails.
Pan the camera around, and move it back and forth. The fiducials will be wobbly due to the lack of genlocking in the Intersense, but they should stay more or less connected to the CG cones.