AVS Modules 3D axis Lawrence Berkeley Laboratory 31 July 1992 Last Modification 31 July 1992 NAME 3D axis - draw a 3D coordinate axis system over a 3D field SUMMARY Name 3D axis Type mapper Inputs field 3D, any data; OR field 2D uniform or rectilinear Outputs geometry Parameters _N_a_m_e _T_y_p_e x axis ticks slider y axis ticks slider z axis ticks slider tick size slider xz plane position slider xy plane position slider yz plane position slider Show xz plane toggle Show xy plane toggle Show yz plane toggle font size slider label precision slider font number slider x label density slider y label density slider z label density slider origin labels type-in Show labels toggle Axis Min typein Axis Max typein DESCRIPTION This module generates 3D coordinate axes for a 3D data set. It will also optionally generate tick marks along each axis, numeric labels for the tick marks, and movable mesh planes perpendicular to each of the axes. Functionality has been added so that 2D rectilinear or uniform fields will be accepted as well. The x/y coordinates are provided with the field, the z coordinates for the axes are computed from the data in the field. INPUT The input is an AVS field which must fit into one of the following categories: 1. Uniform field, 2 or 3 data dimensions, with or without extents. 2. Rectilinear field, 2 or 3 data dimensions, with or without extents. 3. Irregular field, N-data dimensions, 3 spatial dimensions, with or without extents. The data type in the field is irrelevant. Only the coordinate information is looked at. OUTPUT The output is a geometry object consisting of lines forming the axes, with optional tick marks, mesh planes, and labels. PARAMETERS x axis ticks y axis ticks z axis ticks - These sliders set the number of ticks shown along an axis. tick size - This slider adjusts the size of the ticks marks. xz plane position xy plane position yz plane position - These sliders set the position of the mesh planes. This value is in the coordinate system of the axes, rather than being a relative position along the axes (as in previous releases). Show xz plane Show xy plane Show yz plane - These switches turn the mesh planes on and off. Mesh line spacing is determined by tick spacing, so that if there are no ticks shown, there will be no mesh planes shown regardless of the setting of these switches. font size - This slider sets the relative label font height. label precision - This slider sets the number of digits shown to the right of the decimal in the numeric labels. font number - A slider used to select from 22 different fonts. x label density y label density z label density - These sliders set the frequency of label display, relative to tick marks. That is, if n is a label density setting, a numeric label will be displayed every n ticks along the axis. origin labels - This is a type-in field which is scanned for an x, y, and z. For any of these characters present in the string, the origin numeric label appropriate for the respective axis is displayed. This facility is provided to reduce label confusion at the origin. If all axis minimum (origin) values are the same, that value is shown by default at the origin. Show labels - This switch turns tick labeling on and off. Axis Min Axis Max - These type-in fields show, and allow adjustment of, the axis minmum (origin) and maximum (end point) values. If the data set is UNIFORM, adjustment of these fields simply changes the values of any displayed numeric labels. This allows the user to make the labeling better reflect the true dimensions of the data. Addendum to Uniform fields: Uniform fields may be mapped into an arbitrary rectangle in space. 3D Axis may be used to plot an axis with respect to the mapped rectangle. If no extents are present in the uniform field, the axes defaults to -1..1 in x,y,z. If the data set is RECTILINEAR or IRREGULAR, adjustment of these fields will change the actual on sreen location of the chosen points, without changing the labels on the unaffected part of the axis. For example, if the initial minimum x co- ordinate is 10, changing it to 0 would move the axis origin 10 units in the negative x direction. This would have the effect of moving the coordinate axis system origin outside of the displayed data set. But the tick labeled 10 would still be in the same place and it would still be labeled 10. (For further discussion refer to DATA MAPPING below.) DATA MAPPING If the input is a UNIFORM data set then there are no coordinate values stored in the data set and the coordinate axes, along with the data, are drawn in normalized space (see Addendum above). The axis origin is placed in the far lower left corner of the displayed data set. The initial axis min values are set to zero, and the max values are set to the respective dimensions of the data set. These values, and therefore the tick label values, are independent of the actual drawing on screen. If the input is a RECTILINEAR or IRREGULAR data set then the axes, along with the data, are drawn in the world space of the data set. In this case, the origin of the axis system is placed at the minimum world value for each data dimension, and ticks are labeled accordingly. (For a RECTILINEAR data set, this is typically the far lower left corner of the displayed data set). Note that this may or may not coincide with the world origin (0,0,0) which is defined by the data set's stored coordinate information. For example, if the minimum values of the data set coordinates for each axis is 10, then the point (0,0,0) would lie outside of the data set. If the axis min or max values are changed, then the drawn axis will change position or length, but labels will remain consistant with the stored data set (world) coordinates. EXAMPLE The following network shows a typical usage of 3D axis: read volume or read field _____________| | | | field to float 3D axis | | isosurface |_____________| | render geometry | display pixmap RELATED MODULES set extents AVS Module 3D_axis Lawrence Berkeley Laboratory 31 July 1992