The Spherical Orient node is a companion utility to the Spherical Track node, and can be used to orient the six planar cameras that are generated from equirectangular clips.
Camera orientation can be changed in several ways:
- the cameras can be re-oriented to look at a particular location in 3D space;
- the rotation of the camera set can be stabilised;
- a fixed rotation offset can be applied.
Each operation rotates the set of 6 cameras as a whole, and automatically re-generates the image data viewed by the camera from the original equirectangular clip.
After using the Spherical Track node to track an equirectangular panorama, six planar cameras are generated that represent the front, back, left, right, top and bottom views of a cube map surrounding the spherical camera position. The Spherical Orient node can be used to adjust the orientation of this camera set as a whole, whilst also updating the image viewed by each camera.
Orienting a tracked camera
The camera set can be oriented by positioning a look-at target so the 'front' camera (i.e. the first input) is looking at the target point.
The target position can be fixed in position, or freely animated over the entire clip using the Fixed position option. An F-Curve is also available in the curves editor allowing the target keyframes to be adjusted.
Stabilising camera rotation
Instead of pointing the camera at the target point, the stabilisation controls can be used to reduce, or remove entirely, camera rotation from frame-to-frame. The Stabilize % option controls this, with 0% corresponding to the original input motion, and 100% corresponding to a camera where all changes in rotation have been removed, and the cameras point in a fixed direction for the entire clip.
Rotating the camera set
The Rotation edit boxes specify a fixed rotation that is applied to the camera set after orientation has been set using either a front target or stabilisation, and correspond to rotations around the X, Y and Z camera axes.
Clicking the Orient button allows this fixed rotation to be adjusted manually in either the Cinema or Viewer windows.
Rebuilding the camera set after tracking
In some situations, it may be desirable to use another node to track one of the output cameras. For example, if the focus of a matchmoving task is one small area of the equirectangular image, an additional node such as the Camera Solver or Survey Solver can be used.
In this case, the Spherical Track node is used simply to cut the equirectangular image into six planar cameras, and not for the actual feature tracking and camera solving task. Once one of the six cameras is tracked using other means, the Rebuild from menu can be used to rebuild the position of the other five cameras using the motion path of the one that has been tracked elsewhere.
Current Clip: The clip (corresponding to one of the six planar cameras) displayed in the Cinema window.
Camera Cameras: Options are All clips, which will display all camera frustums in the Viewer windows, or Current clip only, which only diplays the frustum for the current clip.
Use front target: Rotate the camera set so the front camera (i.e. the clip in the first input) is looking at the target point. Note than when this option is enabled, stabilisation is disabled because the camera will be focused on the target point. By default, the target point is located at the origin.
Fixed position: Lock the target point to a fixed position in space. When this option is disabled, the target point may be animated over the entire clip.
Adjust: Allow the target point to be adjusted in either the Cinema or Viewer windows using a standard translation manipulator.
Stabilize %: The amount of stabilisation that is applied to the camera rotation. Increasing this value from 0%(the default) to 100% will increase the amount of stabilisation. A value of 100% means all rotation changes are removed, resulting in a camera that is looking in a fixed direction.
Rotation: The fixed rotation that can be applied to the camera set after orientation has been set using either a front target or stabilisation. The edit boxes correspond to rotations around the X, Y and Z camera axes. The R button will reset these values to their default of zero.
Orient: Allows the fixed rotation to be adjusted manually in either the Cinema or Viewer windows. In the Cinema, this can be done by holding the Control key and using the left mouse button to rotate the camera view. Holding the Option key as well as Control will adjust the camera roll. In the Viewer windows a standard rotation manipulator is available.
Rebuild from: Rebuild the position of the six cameras using the current motion path of only one. This can be useful if one camera has been edited or tracked separately from the rest of the cube map set. Selecting one camera from the menu will ensure the others are positioned correctly around it.
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