Rotate on Cartesian Axes
Previous  Top  Next

Dialog Box: Rotate on Cartesian Axes [ Rotation menu]

This rotates the crystal on one of two sets of Cartesian axes. If clinographic viewing is off, the crystal is always rotated about one of the axes belonging to the observer system: x coming straight out towards the observer, y in the plane of the screen or paper pointing to the right and z upwards. If clinographic viewing is on, you can choose to rotate about the clinographic axes, which have been rotated in a certain way from the observer axes (see Coordinate Systems).

Each time you click the Rotate button, a rotation is added to a master rotation matrix; the number of such rotations is listed at the bottom of the dialog box. When you have finished rotating, click the Done button and the master rotation matrix is applied to the crystal. If you click Cancel , no rotations are applied.

In Standard mode, the clinographic and observer axes are roughly similar. However, in Stereonet mode (selected in the Modes menu), they are distinctly different. In this mode, you are considered to be viewing the crystal down the c axis, instead of down the a* axis (or approximately so, if clinographic viewing is on). Thus the clinographic z axis comes directly out of the screen or paper, the x axis is downward and the y axis is to the right - in other words the clinographic axes are rotated by 90 degrees with respect to the observer axes. As noted in Coordinate Systems, when rotating about the clinographic axes, the crystal can be considered to be rotating in its own coordinate system, while the user may have different points of view: in Standard mode with clinographic viewing off, looking directly down the x axis; in Standard mode with clinographic viewing on, looking down a direction which is up and to the right from the x axis; and in Stereonet mode, looking directly down the z axis.