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Camera Offsets

Previzion lets you move the virtual scene wherever you desire, and still have the physical camera move correctly through the scene. This is done without moving the virtual scene itself, so that all tracking data will map correctly back to the original virtual file.

The Camera Offset panel shows the current X, Y, Z, and Pan offsets. Tilt and Roll are always taken directly from camera tracking data to avoid confusion and are not editable.

As the virtual camera position is edited in the Camera panel, the XYZ Camera Offset will change in real time to compensate.

Press Reset to zero any axis.

To pan the virtual camera without moving it, click and drag up or down on the **Pan Offset** box. As with other controls, fine control is achieved by holding down **Control**, and rapid motion by scrolling the mouse wheel. The XYZ offsets will change in real time to keep the virtual camera in the same place during the panning process.

Set Floor Offset

For scenes that has floor or ground, it is often crucial to position the camera height offset to match the conditions from the greenscreen.  Ordinarily, when a stage is surveyed, we set the instrument height to the floor as the reference start of the y-axis (height or up and down axis).

When the camera is positioned over this floor or ground geometry, Set Floor Offset measures the distance between the camera and the floor geometry.  This is a quick way to align the physical camera height and the virtual camera height.

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Saved Camera Locations

When the scene file is loaded, Previzion’s scene loader reads in all of the virtual cameras that are part of the file, and makes a list of them. Each virtual camera position can be jumped to immediately by selecting it from the **Camera Locations** drop down menu. As before, the Tilt and Roll data is not used.

This lets a director set up a list of desired camera positions for specific shots, and store them into the FBX file for rapid use.

After the new camera reference location has been selected, make sure to set the proper Y offset to keep the virtual floor and the live action floor aligned.  Use Set Floor Offset to set your height.

Save new Camera Locations

To save new camera locations, you may position the camera where you would like it to be saved at and use Add Current.

Name your location for later use to save time and plan shots.

The location is then stored in the Camera Location panel’s drop-down menu.

Angle Reference System

Many different 3D applications have different zero angles for the camera. Previzion defaults to the Motionbuilder angle reference system, where by default the virtual camera points down the +X axis.

The default Motionbuilder zero angle system works well in practice for most applications. Previzion’s data capture system uses Collada, which has its own defined coordinate system that all applications supporting Collada are required to transform into and out of properly, so this setting is independent of the software used to create the FBX background file.