Subject: MHEG DIS letter ballot

From: "Wolfgang Herzner OeFZS/Dep.IT +43 2254 780 3121" <[email-masked]>
Date: Mon, 23 Jan 1995 19:53:33 EST

Dear member of SC24,

as liaison officer to SC29/WG12, I want to inform you that the letter ballot
on ISO/IEC DIS 13522-1 "MHEG object representation - base notation (ASN.1)"
is now out and terminates on 1995-04-15.  The document can be received via ftp
129.63.24.2/pub/MHEG/DIS
where you will find the following files:

total 7794
-rw-r-----   1 79       1026     1326958 Jan  5 07:44 DIS-1.ps.gz
-rw-r--r--   1 79       1026      139238 Oct 17 12:54 DIS-1.rtf.gz
-rw-r-----   1 79       1026     1335533 Jan  5 07:48 DIS-2.ps.gz
-rw-r--r--   1 79       1026      193807 Oct 17 13:10 DIS-2.rtf.gz
-rw-r-----   1 79       1026      803993 Jan  5 07:52 DIS-3.ps.gz
-rw-r--r--   1 79       1026      117011 Oct 17 13:17 DIS-3.rtf.gz
-rw-r-----   1 79       1026         171 Jan  5 05:35 README

Since the rtf appear pretty old, refer to the *.ps.gz files (gzipped).

I will bring your special attention to chapter 53 (persumably in DIS-2.ps.gz),
which describes spatial behaviour.  It is a pretty complex model, but appears
relatively 'unclean' to me with respect to SC24's way to handle simple
spatial transformations (e.g. in revised GKS).

Another aspect is that MHEG does not support rotation of (content) objects
before display, not to mention perspective views, although 3 spatial
dimensions are supported.  The basic reason is the restriction that content
should be presentable with minimal rendering effort as possible ('final form').
However, stretching (parallel to coordinate axes) appears to be supported.

The question is if this restriction is a crucial defect SC24 (e.g. PREMO when
looking at MHEG as interchange format at the display level) cannot live with.

Best regards
                 Wolfgang Herzner
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  Wolfgang R. Herzner
  Dep. Information Technology  (IT)
  Austrian Research Centre Seibersdorf
  A-2444 Seibersdorf
  tel: +43 2254 780 3121    (secr.: 3118)
  fax: +43 2254 74060
  e-mail: [email-masked]  OR  [email-masked]
      or  PSI%0232-26221064::HERZNER
  X.400:  C=CAT; A=ADA; P=ARCS; S=HERZNER
----------------------------------------------------------------------