From Barbara.Jeanne.Lurvey@omail.wang.com Tue May 26 06:58:54 1995 Received: from tuna.wang.com by dkuug.dk with SMTP id AA03820 (5.65c8/IDA-1.4.4j for ); Fri, 26 May 1995 17:07:18 +0200 Received: from w0000993.corp.wang.com by tuna.wang.com with SMTP id AA11496 (5.67b/IDA-1.5 for ); Fri, 26 May 1995 11:06:51 -0400 Received: by w0000993.corp.wang.com (AIX 4.1/UCB 5.64/4.03(4/24/95)pmob) id AA23156; Fri, 26 May 1995 10:58:12 -0400 Date: 26 May 1995 10:58:54 -0400 From: Barbara Lurvey O/o Subject: Clarification of 3DM NP To: SC24@dkuug.dk, bjl@wang.com, puk@megatek.com Priority: Low Sensitivity: Minimum Type: Memo Message-Id: X-Charset: ASCII X-Char-Esc: 29 Dear SC24 colleagues, I have been asked several questions about the U.S. proposed new work item for a Three-Dimensional Metafile for Computer Graphics (3DM). 1. How does this NP relate to SGI's Open Inventor work? Is it to validate the the SGI work or to be an anti-SGI effort? 2. Doesn't SC24 already have a 3D metafile in the PHIGS Archive protocols? I want to share my responses with all of you. 1. Requirements for standardizing a 3D Metafile for Computer Graphics have been considered since SC24 was first established and several efforts have actually been started. The US recognized last year that time is running out for such an effort and thus solicited contributions from the computer graphics community. In October, 1994, presentations were made to our X3H3 technical committee members by representatives of Apple Computer, Silicon Graphics (SGI), and InterCap. A report was also received recommending the use of STEP. The important shared observations from these presentations were: - The need for a 3D cross-platform graphics format was recognized as an urgent requirement by most developers. The market is currently hindered by the lack of such a standard. - The markets that must be addressed are broad and horizontal in nature, rather that narrow and vertical. A decision followed to try to leverage the work on SGI's Open Inventor. The Open Inventor file format (not the application environment) was chosen as the basis for this work. A review of this format indicates that, unlike OpenGL, the functionality involved is similar to PHIGS. The file is intended to be a picture capture metafile which also retains the structure of the data so that the information can be modified at the interpreter end. There was a careful assessment made of the organization's willingness to contribute designs and modify them in order to produce a single ISO 3D Metafile standard as well as the commercial acceptance and availability the current work. SGI has been most cooperative, including offering a project editor. 2. In CGRM terms, the intent of 3DM is to capture "scenes" at the virtual environment level whereas the PHIGS archive files capture all or part of the collection store at the construction environment level. 3DM is intended for interchange of 3D scenes at the PHIGS Workstation level. A scene database is defined which contains shapes, properties and other aspects of the graphical "elements" being described. Light and cameras give the information necessary to render the "elements." I hope this helps, Barb