Minutes of Network Graphics Group meeting, 15-17 July 1973
RFC 549

Document Type RFC - Unknown (July 1973; No errata)
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Network Working Group                                          Anonymous
Request for Comments: 549      Center for Advanced Computation, U of Ill
NIC: 17795                                               15-17 July 1973


Sunday evening, 15 July

   The meeting came to order around 1930, Jim Michener presiding.  After
   introductions, an agenda was constructed for the rest of the meeting.

   Elaine Thomas distributed copies of an Alternative Network Graphics
   Protocol for attendees to read overnight prior to discussion.

   Because some individuals were absent who had definitely indicated
   that they were coming Monday morning, the meeting was adjourned at
   2030 after deciding to meet at 0930 the next morning.

Monday Morning/Afternoon, 16 July

   The meeting was called to order at 0930

   Jim Michener distributed an outline of a paper describing desirable
   facilities for the use of two dimensional input devices with a
   hierarchically structured display program.

   Ken Victor distributed copies of RFC 553: A Proposed Network
   Text/Graphics Protocol. (LJOURNAL,17810,)

   Ken Pogran described the history of the NGG and how the "levels"
   approach of RFC 493 came about.  In particular, the "level 0"
   protocol was an attempt to define something to experiment with, but
   with the thought that it should be possible to imbed "level 0"
   meaningfully in any later protocol.

   Reports of Network Graphics Experiences

      Jon Jervert described the installation at CAD/CAM (Fort Monmouth).
      They have a spectrum of display terminals and have tried several
      via a Telnet connection to MIT-DMCG.  They experienced
      unacceptable slowness with a 300 Baud bandwidth.

      Austin Henderson described an Air Traffic Control experiment in
      which the simulator receives codes describing changes in state and
      generates descriptions of the air space (region) being controlled

                                                                [Page 1]
RFC 549               Minutes of Network Graphics        15-17 July 1973

      and aircraft position and velocity.  These descriptions are highly
      encoded--they are not pictures in any general sense.  The rate at
      which the simulation proceeded was adequate.

      Jim Michener described the results of an experiment in which the
      E&S LDS-1 at MIT-DMCG was used to generate stylus inking input for
      a character recognition program at SDC.  The experiment was
      plagued with difficulties including bugs in SDC's NCP and
      scheduling of experimental/debugging sessions.  When the
      experiment was finally terminated (due to planned extensive
      hardware modifications at DMCG) a clear understanding had not yet
      emerged, but apparently network transmission delays had been
      experienced of up to 20 seconds.

      Dan Cohen described an Aircraft Flight Simulator which interacts
      with a user at the Harvard PDP-1.  The simulation takes place on a
      PDP-10.  Network traffic is approximately 200 bits from the PDP-1
      to the PDP-10 and several thousand bits in the opposite direction.
      It has been found that at least 5 updates are required per second
      to give the "pilot" an adequate feeling of control.  The Harvard
      PDP-10 and one at BBN have been used, the latter at 6 AM to avoid
      loading problems.

      John Pickens described UCSB's status regarding output in level 0
      Network Graphics Protocol (NGP-0).

      Steve Bunch reported that he has an Imlac monitor which accepts
      NGP-0 directly.  Programs have been developed at CCN (using
      subroutine packages modeled after plotter packages) which build
      files containing pictures in NGP-0.  Other programs output the
      pictures either to a Gould plotter or a storage display (in device
      specific code) or to an Imlac (in NGP-0 form).

      Steve Holmgren briefly described a Fancy Arpa Network Graphics
      System (FANGS) under development at UCSD.

   Discussion of Modifications in the Graphics Protocol

      David Egli reported that he and Jim Foley (of Univ. of North
      Carolina) thought that the graphics protocol should have the
      ability to replace items, and that 3 dimensional data should be
      allowable.  Jim Foley also thinks that a subpicture call should be
      able to specify a rate of rotation, scaling, and translation, in
      addition to initial values for these.

      An extended coffee break followed to allow perusal of the
      documents distributed.

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RFC 549               Minutes of Network Graphics        15-17 July 1973

      Elaine Thomas summarized her protocol proposal for a
      hierarchically structured, editable display file.

      Discussion related to the levels approach of RFC 493 concluded
      that levels were inappropriate; we would henceforth think in terms
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