The orientation of the probe is determined by three angles, theta, phi, and psi, that can be manually specified.
- The theta angle specifies the horizontal angle between the positive X-axis of user space and the positive X-axis of the probe.
- The phi angle is the angle of rotation between the positive Z-axis of the probe and the positive Z-axis in user space.
- The psi angle is the angle of rotation about the axis determined by phi and psi
- The orientation is determined by first applying a rotation by psi in the X-Y plane, then by applying a rotation of phi in the X-Z plane, and applying a rotation of theta in the X-Y plane.
- The orientation can be interactively specified using three thumbwheels that control the rotation about X, Y, and Z-axes.
- "Axis Align" and "90 degree rotation" selectors in the tab enable the probe to be aligned with any axis, or rotated by 90 degrees about any axis.
Rotating the probe in stretched domains. When the probe is rotated and the domain is highly stretched, users may be surprised to see that the probe appears to suddenly become very long in the direction of the stretch, due to the fact that the rotation takes place in Cartesian (unstretched) coordinates. It is useful to click the button "Crop to Domain" or "Crop to Region" to maintain the probe within the current region of interest.
