When the Contour Definition Menu is spawned specifing one of the plot axes to be a function of Contour, the Method option in the Contour Definition Menu is enabled. Selecting RANDOM(3D) as the Method creates one instance of the 3D Plane Definition Menu. The menu is created silently that is it does not pop immediately up onto the screen but is added to the Menu List in the lower section of the Control Panel and from there it can be brought into the foreground if needed.
This menu contains all the options needed to define a plane through a 3D data set onto which a contour will be projected. A contour mesh is placed on the plane and the values at the mesh points interpolated through a 3D least squares fit using the nearest data points. The base plane is defined to contain the origin of the data (0, 0, 0) and to have a normal vector which is defined in the menu. The base plane can then be translated in either direction along the plane normal.
The menu can also be used to set up a sequence of steps though which the defined contour plane can be rotated and/or translated. A contour is produced at each step allowing for the data to be viewed at a number of cuts.
The menu has the appearance:
CLOSE closes the 3D Plane Definition Menu window.
NORMAL VECTOR SOURCE defines the how the vector normal to the contour plane is to be defined. The options are:
| Option | Definition |
|---|---|
| USER | The user must enter the normal vector in the VECTOR DEFINITION entry boxes on next option line. |
| UDF | The Normal Vector is derived from a UDF source. Selecting this option will pop up one instance of the Vector Source Menu. |
VECTOR DEFINITION is enabled only if the Normal Vector Source option has been set to USER. The normal vector is specified by giving the two spherical angles defining the vector. The first entry box is for the phi angle (angle in the XY plane) and the second entry box is for the polar or elevation angle (angle measured from the XY plane with positive angles used in advancing toward +Z and negative angle used in advancing toward -Z).
INITIAL RHO specifies a rotation angle about the normal vector. This allows the contour plane to be rotated about normal. If the rotation is to occur in steps then this is the beginning rotation angle in the sequence.
INITIAL TRANSLATION specifies the distance to translate the contour place along the normal. A positive translation is in the direction of the normal vector. If the translation is to occur in steps then this is the beginning translation in the sequence.
NUMBER OF STEPS specifies the number of steps to use in taking the contour plane from an initial orientation to a final orientation. A contour of the data is produced at each step. If no steps are required (the initial contour place definition is the only required plot) then the value is set to 1. The option is useful to see a distribution at a number of cuts.
CONTOUR PLANE ROTATION defines the final orientation of the contour plane X axis. Once the base contour plane has been established, the normal to that place becomes the new +Z axis and the XY axis establishes the plane. With this option the X axis of the base contour plane can be rotated to any of the other prime axes. This is done by recomputing the normal. As an example, if the X axis of the base plane is rotated to the +Z axis (the plane normal) then the contour plane would be the YZ plane in the base coordinate system.
| Option | Definition |
|---|---|
| X Axis | Default condition - no rotation occurs. |
| Y Axis | Rotate the X contour plane axis to the Y contour plane axis. |
| Z Axis | Rotate the X contour plane axis to normal vector |
| -X Axis | Rotate the X contour plane axis to the -X contour plane axis. |
| -Y Axis | Rotate the X contour plane axis to the -Y contour plane axis. |
| -Z Axis | Rotate the X contour plane axis to lie opposite the normal vector |
ROTATION STEPS is enabled only if the Number Of Steps option is greater than 1. The three entry boxes specify the rotation step sizes of Phi, Theta and Rho angles to take in each orientation step of the contour plane. All values are in degrees.
TRANSLATION STEPS is enabled if the Number Of Steps option is greater than 1. It specifies the translation step size to use in each orientation of the contour plane. The value is given in terms of the data units along the X and Y axes.
The following examples show the effects of some of the options available through the 3D Plane Definition Menu.
Normal and Translation Options
A set of 3D electron data is plotted using a 3D Contour. The plane on which the data is rendered is established by using the local magnetic field as the plane normal. It is then translated along the normal. The menus which establish this are:
The resultant plot to which a set of 1D Cuts has be added and with the parameters defining the contour plane given above the plot is:
The contour plane is translated from -5000 km/sec to 5000 km/sec in 25 steps. Each step is 500 km/sec. A contour plot is output at each step.
All 25 plots are output on a single page as:
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