


                                  - 1 -



       COMMAND

       llllggggiiiinnnnccccrrrr,,,, llllttttiiiinnnnccccrrrr ---- ddddiiiissssppppllllaaaayyyy oooorrrr sssseeeetttt ccccoooooooorrrrddddiiiinnnnaaaatttteeee ggggrrrriiiidddd iiiinnnnccccrrrreeeemmmmeeeennnntttt

       USAGE

       llllggggiiiinnnnccccrrrr [_i_n_c_r_e_m_e_n_t]

       llllttttiiiinnnnccccrrrr [_i_n_c_r_e_m_e_n_t]

       DESCRIPTION

       LLLLggggiiiinnnnccccrrrr and llllttttiiiinnnnccccrrrr provide a means of setting the longitude
       and latitude _i_n_c_r_e_m_e_n_ts.  These _i_n_c_r_e_m_e_n_ts are the relative
       spatial separation between data points in the image.
       Alternatively, you may use either command without argument
       to display the current value of the _i_n_c_r_e_m_e_n_t of interest.

       For cylindrical images, the longitude _i_n_c_r_e_m_e_n_t is expressed
       in microradians.  For cartesian images, the longitude
       _i_n_c_r_e_m_e_n_t is expressed in microns.

       In the case of cylindrical scans, the longitude _i_n_c_r_e_m_e_n_t is
       the angular separation between the 512 successive profiles
       sampled by the digitizer, 0.703125 degrees or 0.012227
       radians.  The latitude _i_n_c_r_e_m_e_n_t is the separation between
       the 256 evenly spaced planar subdivisions of the axial
       (vertical) extent of the (cylindrical) digitizing zone.
       This separation in the standard configuration is 1/256 of
       the 400 millimeter high active zone or 1.563 mm.

       The 512 profile curves which make up the _E_c_h_o digitized
       image are regularly spaced samplings of the radial distance
       from the axis of digitizer rotation to the space curve
       defined by the intersection of one of 512 evenly spaced
       axial (vertical) half-planes with the surface of the subject
       being digitized.  The sampling interval along a particular
       profile is defined by the intersections of that particular
       profile with the regularly spaced horizontal planes making
       up the latitude range.

       In light of the foregoing discussion, llllttttiiiinnnnggggrrrr and llllggggiiiinnnnggggrrrr are
       a means for satisfying the need to modify the spacings of
       the planes which define the geometric structure of _E_c_h_o
       digitized images whenever they depart from the standard
       configuration.  A prime example involves rectilinear
       digitization scans wherein the data points comprising the
       digitized image are the heights of surface features above a
       fixed datum plane.  The digitizing zone is subdivided into a
       uniformly spaced rectangular grid of intersecting planes,
       dubbed latitudes and longitudes by analogy to the











                                  - 2 -



       cylindrical case.

       The sequence of longitudes is defined by 512 evenly spaced
       planes lying perpendicular to both the datum plane and the
       the path of relative motion between the subject being
       digitized and the digitizer itself.  The sequence of
       latitudes is defined by 256 evenly spaced planes lying
       perpendicular to both the datum plane and the sequence of
       longitude planes and lying parallel to the path of relative
       motion between subject and digitizer.

       Since the longitude _i_n_c_r_e_m_e_n_t is no longer an angular
       separation but rather a linear separation, the appropriate
       _i_n_c_r_e_m_e_n_t can be set or revised with llllggggiiiinnnnccccrrrr.  Similarly, the
       latitude _i_n_c_r_e_m_e_n_ts, often quite different from the standard
       cylindrical case, can be set or revised by llllttttiiiinnnnccccrrrr.  In the
       latter case, since these arguments express linear measure,
       they need to be expressed in microns.

       Both lgincr and ltincr can be employed without argument in
       order to obtain a display of the values assigned under the
       current image.  For example, the command llllggggiiiinnnnccccrrrr might return
       the following:

       LLLLoooonnnnggggiiiittttuuuuddddeeee iiiinnnnccccrrrreeeemmmmeeeennnntttt ==== 11112222222277772222uuuurrrr ((((oooorrrr uuuummmm))))

       You must bear in mind the the current geometry when
       interpreting the response from llllggggiiiinnnnccccrrrr.

       NOTES

       A typical longitude _i_n_c_r_e_m_e_n_t for relief images which have
       been transformed from cylindrical to cartesian space is 781
       microns.

       A typical latitude _i_n_c_r_e_m_e_n_t is 1563 microns for the usual
       4020 digitizer scan whether cylindrical or linear.  This
       value is normally scaled automatically by either of the
       image scaling commands.

       Cartesian images made at Cyberware usually have a longitude
       _i_n_c_r_e_m_e_n_t of 147 microns.

















