Path: utzoo!attcan!uunet!samsung!dali.cs.montana.edu!milton!watserv1.waterloo.edu!broehl@ria.ccs.uwo.ca From: watserv1.waterloo.edu!broehl@ria.ccs.uwo.ca (Bernie Roehl) Newsgroups: sci.virtual-worlds Subject: Re: Cyberspace, VR, a summary of what I've seen so far... Message-ID: <7624@milton.u.washington.edu> Date: 14 Sep 90 19:23:40 GMT References: <7511@milton.u.washington.edu> Sender: hlab@milton.u.washington.edu Organization: University of Waterloo Lines: 71 Approved: hitl@hardy.u.washington.edu In article <7511@milton.u.washington.edu> zap@lage.lysator.liu.se (H}kan Anderss on) writes: >** The 'protocol' that has been mentioned and partially designed in this >newsgroup is interesting, but I see some limitations.... > F'rinstance, why limit the placement of an object to three >dimensions? Who said cyberspace isn't 7-dimensioned? Or 37.3 dimensions? >Supply a coordinate count and a number of coordinates. For now, and in the >forseeable future, the count will be 3 and the coordinates will be X, Y and >Z, but you wanted extensibility... The idea of "attributes" is nice because it *is* extensible... we specify at attribute as "position" and have its value be x, y, z. Once we figure out a way of handling more dimensions, we can "expand" the object by giving it additional attributes for the "extended" dimensions (say, an attribute called EXTENDED_POSITION that, as you suggest, has a coordinate count and an essentially unlimited number of coordinates). Objects that have POSITION but lack EXTENDED_POSITION are simply "flat" in the unused dimensions. >..... As for the appearance description of >an object, i.e. how-the-darn-thing-looks, then why reinvent the wheel >when this already exists: RenderMan. I already suggested RenderMan in an earlier article; however, the RenderMan appearance of an object is only *one* representation, and simpler (wire-frame or whatever) versions should be present as well. Small computers may not implement even a subset of RenderMan, but still want to know the basic size and shape of an object. Some objects may not even have a visual appearance at all, but exist on some other sensory level entirely. >Fr'instance, at the 'lowest resolution', >some chunk of data might just be a blob, a pixel, a tone, a smell of burnt >rubber or an image of a talking applepie. At a higher 'resolution', higher >level-of-detail, the same object might have a 'shape' (or smell, flavor or >spice)... Right -- exactly! >The only drawback in using renderman is the little line in the RenderMan >spec that says that you must respecify the entire scene for each frame. To >reduce load on the net, we need an extended version of renderman, where you >only respecify those objects you really need to. Since the frame rendering is done on the local system, not on the host, this isn't an issue; you keep track of each object's RenderMan specification, and alter their position/orientation whenever the room tells you that the object has moved. (This brings up a point I forgot to mention earlier; the building is responsible for event synchronization, so that I move at the same "time" from the standpoint of every occupant of the room, and the "swooshing" sound I make is co-ordinated with my movement). >But have anyone thought of the similarity between cyberspace and >the GUI's of modern computers? Yes. (At least, *I* have -- and I assume others as well). >In a sense, cyberspace is already invented, but today it's only two- >dimensional, it sits on the screen in front of you. Right. The extension to three dimensions is a critical element, as is the notion of "sharing" that world with other people. -- Bernie Roehl, University of Waterloo Electrical Engineering Dept Mail: broehl@watserv1.waterloo.edu OR broehl@watserv1.UWaterloo.ca BangPath: {allegra,decvax,utzoo,clyde}!watmath!watserv1!broehl Voice: (519) 885-1211 x 2607 [work]