Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!uwm.edu!ogicse!milton!hlab From: galt@hellgate.utah.edu (Greg Alt) Newsgroups: sci.virtual-worlds Subject: Re: VR hardware safety response Message-ID: <1991Jun5.223957.631@milton.u.washington.edu> Date: 5 Jun 91 04:06:28 GMT References: <1991Jun5.031158.15999@milton.u.washington.edu> Sender: hlab@milton.u.washington.edu (Human Int. Technology Lab) Organization: University of Utah, CS Dept., Salt Lake City Lines: 83 Approved: cyberoid@milton.u.washington.edu In article <1991Jun5.031158.15999@milton.u.washington.edu>, kilian@poplar.cray.c om (Alan Kilian) writes: > galt@hellgate.utah.edu (Greg Alt) Says: > > > but what about LCD screens? > > While there is little or no radiation, it is still looking at something > > only a few inches away from your face. I would think this is not good > > and could cause some pretty bad eyestrain. > > Well, not really. The screen is only a few inches from your face but it > is optically much farther away. Some people say "Optical infinity" but it > seems more like one meter or so to me. Well, that makes sense... So I guess eyestrain would be only as bad as using a normal monitor (more or less). > > I wonder what the effect of the optics are on the LCD screen. I would > > hope they take the screen farther away from your eyes and enlarge it, > > They do make the screen seem farther away but they don't really "enlarge" it. > Well they do, but not really. it's like this: > > /| > / | > / | > / | > / | > / | > /| | > / | | > / | | > Your eye-----> . | | You are looking this way ---> > \ | | > \ | | > \| | > \ | > \ | > ^ \ | > | \ | > | \ | > | \| > | > | ^ > | | > The "real" position ---+ +--- The optical position of the screen. > ofn the LCD screen > > So the screen "looks" bigger because you think it's farther away, but it does > not subtend a greater solid angle so it's not really "enlarged" That's disappointing. I would think it would be good to make the screen appear enlarged, but I guess at a few inches from your face, the display would have a large angle. > > Also, in a couple weeks, I will start to work on a simple 3D graphics > > system that has perspective views. I will write it in Turbo C, and > > I will post it (or send it to the new cheap-VR ftp site). I plan on > > using a hierarchical structure similar to PHIGS, and it will be flexible > > with color and depth cueing. If anyone has comments or suggestions, > > please email me... I plan on not supporting lights, but I think I > > will leave some hooks to allow expansion... > > What are you trying to get? There are many public domain 3D graphics > systems out there that support all of this. If you are trying to really > understand 3D than this is the way to go but if you just want to be able > to draw things get something like the simple phigs package from brown > university. (Mail to spr@cs.brown.edu because I can't find the IP number) > they have a PHIGS package that runs with the X-Window system. I would rather write my own so that it is easy to use with a PC and easy to modify. Actually, I cranked out a big part of it last night. I already have functions to generate all the matrices, and I plan on re-writing them to use fixed-point instead of floating-point (I don't have the $400 for a 387). I also have the hierachical structure setup to allow executing other structures... It will only allow polylines and polymarkers, since the VR system I will make won't be able to handle polygons (386's are too slow). But I will leave hooks for this so that it can be added later (I also have code for fast polygons...) Greg