Finding the nodal point, consists in fact in finding the ideal rotation point.
To do this, we are going to align, from different angles, two objects, one in the real studio (for example a 30×30×30 cm cube), the other the same object in the 3D virtual scene in Kinetic. If the alignment of these two objects remains constant, regardless of the angle from which they are captured, then we rotate around the nodal point. Otherwise, an adjustment must be made.
Place the cube in your studio and create a box in your 3D scene with the same size and position than the real cube.
On a timeline drag and drop the Deltacast media input from the Media list and the 3D camera AR from the 3D scene and display them in your Vnode output.
Click on the Camera AR layer and in the Editor window, set the Alpha to 0, activate the Wireframe option and choose Kinetic in the Distrotion mode drop down menu.
Set your Camera zoom value at 0 and focus on the cube and place it in the center of the camera (for best results, we recommend setting the tilt value to 0°).
Make a Find pose as seen in the previous paragraph
After this setp, your virtual object should map to the real one in the camera view.
Make a pan movement.
The virtual object doesn’t map to the real one: adjust the Z component of the mounting offset as much as possible.
Otherwise adjust the Z offset to align the centre edge of the virtual cube with the centre edge of the real cube.
Replace the cube in the center of the camera and make a Find pose again. Make a pan movement and adjust the Z component of the mounting offset if necessary.
Repeat these actions as many times as you think necessary.
Then go to Nodal tab and click on Add point.
Click on the Index button to save the zoom and Z mounting offset values.
Set the z mounting offset value to 0.
Repeat all these steps for many different zoom values.
Then click on Calibrate.
The system will calculate the nodal point curve.
You can change the way the points are considered for the cacul of the nodal point curve.
It is up to you to choose what best fits your setup.
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