
VIEWIMAGE(PERSPECTIVE)       Khoros        VIEWIMAGE(PERSPECTIVE)

     Viewimage displays plots from a Perspective projection,
     similar to the xprism3 plotting package.  There are three
     fields which are relevant to the perspective: eye distance,
     alpha, and theta. The eye distance controls the distance
     from the eye to the object;  alpha determines from what
     angle on the Y/Z plane your eye is looking at the object,
     and theta determines from what angle on the X/Y plane your
     eye is looking at the object.  Remember that in our coordi-
     nate system, X goes left and right, Z goes up and down, and
     Y goes in and out (this setup has Y and Z reversed from what
     is taught in many textbooks).

     The Perspective subform of viewimage offers several fixed
     perspective views.  These include a front view, a back view,
     a left view, a right view, a top view, and a bottom view.
     For your convenience, these may be set with the mouse, and
     no thought need be given to the values of alpha and theta;
     they will be updated accordingly. Alternatively, the "eye",
     "alpha", and "theta" float selections may be used to move
     the elevation data to the desired perspective.

     IMPORTANT: unlike xprism3, which uses a set of axes to
     represent the plot, viewimage will rotate the entire exist-
     ing plot as you change these values.  Thus, you are advised
     to use only the 3D or Wireframe plot types while you change
     the perspective.  If you use one of the plot types with a
     more complicated algorithm (color mesh, for instance)  you
     will find the slow redraw time extremely frustrating.

          eye: moves the eye closer (as the eye distance
          decreases) or farther away (as the eye distance
          increases).

          alpha: rotates about the X axis clockwise as alpha
          increases, counter - clockwise as alpha decreases.

          theta: rotates about Z axis clockwise as theta
          increases, counter - clockwise as theta decreases.

          Copyright 1991, University of New Mexico. All rights
          reserved.

Version: 0                 Release: 1                           1

