From: jpc@tauon.ph.unimelb.edu.au (John Costella) Subject: Re: PHIL: VR and VISUAL FORMS (reply to John Costella) Date: Fri, 20 Nov 92 0:30:22 EST Disclaimer: the following post is a little long; brain death upon ploughing through it is your responsibility. :) I have, however, tried not to "quote" excessive bits of previous posts, though. > Let me first thank John Costella for reading, and interpreting for No problems, Tom. > all of the technical postings, etc., which are very difficult going for me. > An example may be the Gallilean Anti-Aliasing posting which is still > challenging me. Yes, I got that back-hander. We must look like Laurel and Hardy trying to understand each other. > > represented a unified field of dimensional values because space, time, > > and body are incorporated into a single expression of rate. > > > > This sounds like gobbledegook to a physicist. At least for the scientific > > I would like to point out for the physicists who begin to feel quite smug at > this point that within the mathematical heritage of ancient Greece Euclid > suddenly created these distinct categories of space, time, and body Ah, OK, I'm getting the (general) drift. The term `rate' may be one that is another scientist-misleader. I take this one back, pending seeing the full paper. > > General relativity > > ------------------ > > I will use theories of general relativity, first touched on during > > discussions of Cubist temporal notations, to illustrate some > > > > A physicist must be allowed to barf upon reaching these paragraphs. One > > might conceivably imagine that the term "general relativity" has an > > artistic meaning completely distinct from its physics meaning; however, > > mention of "inertial frames" and "local effects" makes this impossible. > > Please feel free to barf, I am not offended at my naivet, and I hope you > aren't either; these efforts at communication across disciplinary boundaries > are sometimes very gut-wrenching. OK. . Sorry about that. It's just that GR is about the *only* physical theory that really seems to be A-OK, and we don't like it thrown around recklessly. (Non-Euclidean) geometry is a term I'd be happy with. > > The general laws of nature are to be expressed by equations which > > hold good for all systems of coordinates, that is, are generally > > covariant with respect to any substitutions whatever (generally > > This covariance is precisely what I mean to convey, and they are not well > attended to in the modern or classic theories of visual forms. In > contemporary visual theory we have been content with a rather antiquated > Gallilean framework in which the arbitrary framework (undone, rebuilt?, by > Albert) are still substantially in place. Hmmm. I'll reserve my opinion on this pending seeing the full paper. The Galilean framework is very close to the Einsteinian one; in special relativity the only difference is the speed of light; in GR we're really talking about laws of physics, i.e. dynamics, not simply kinematics (although that distinction is a bit blurred). You might be surprised how powerful Galilean relativity really is (when applied properly). Of course, you might be noting those times that it is not. > As a matter of appropriate use, Albert borrowed a perceptually based model > to found his physics arguments on; ie the tram or gondola perceptual models. > These models, which John uses in his GAA paper, are equally valuable in both > physical and perceptual models; but recognition of this has been slow to > occur. I am willing to risk the criticisms of the physics, and perceptual > psychology, communities in bringing this long overlooked asset into view. > These mathematically founded models of theoretical physics can be very > helpful in perceptual psychology's recognition of an embodied visual form. Hmm. Can't argue this one without criticising myself. > > but by no means the only one. I fail to see any connection between > > gravitation, though, and the topic of Thomas's paper. > > Here is a very important point, and contribution to the argument by John, > that I did not fully explain. I don't intend to use a gravitational > 'mechanism' in explaining the form of a binocular visual field, rather, I > intend to borrow a descriptive technique long accepted in the study of > physics. The descriptive technique in physics itself, as mentioned above, > grew out of a perceptual 'thought experiment' (in the tradition of > Leonardo), which I believe may be appropriate to both physics and perceptual > matters equally. Oh, OK. Full agreement with this goal. A few modifiers in the intro (such as ``*like* the methods used in GR) would make a world of difference, IMHO. > We tend to be drawn toward things of interest in the visual field, and place > what is commonly called the fovea of our vision upon that feature which most > interests us. This is not a gravity well, which would be appropriate in > physics as related to inertial frames etc., but descriptively these formal > structures of perception are similar in character to the notion of an > inertial frame. Each of us, as we move through our environment focuses at a > given distance according to our rate. These distances of focus change > according to our changing rate of movement and mass; in a truck of a given > mass our focus is further from us due to the unique inertia, compared for > instance to a bicycle with less mass. OK. The old ``rubber sheet'' version of GR, eh? Yeah, I think this could be quite valuable, visual-perceptionally speaking, if it were done well. I'd probably use different *words* to say what you just said (quite different, in fact :) but I'm getting your drift. Maybe we could sit down (over e-mail) and negotiate a common language? :) > > However, having bagged geometry, both Euclidean and non-, I suppose he > > would be reticent to put it in those terms :). > > I haven't bagged Geometry per se, but feel that where it performs a > disservice it ought to be reformed. OK, we disagree about its disservice. Maybe what you were told about ``geometry'' was not the whole story. > > Disproving mathematics without mathematics? > > ------------------------------------------- > > > > Err ... either the question is mathematically describable or not. If not, > > then the affine transformations were misapplied; if so, then you cannot > > disprove them by discarding a mathematical description of the world! > > In this case the affine transformations were clearly misused, and that is > demonstrably so. Just as Euclid's projective techniques are inadequate to > perspectival problems, so are LaGournerie's techniques inappropriate to any > sort of perspective other than parallel arrangements. DEMONSTRATIONS UPON > REQUEST; in my studio only (until I can deliver images of a sufficient > quality to the archives of virtu-l). :-( No piccies? > Mathematics are not discarded by myself, but current techniques are simply > inadequate to the task. Anyone want to have a go at it? If I can glean some more details from you via e-mail, I'll give it a burl. > > Euclidean assumptions > > --------------------- [... Tom bags Euclid ...] [... I bag Tom ...] :) > The assumption (in particular) that I wish to question is still in place, > found in post-Euclidean Geometry, and not necessarily appropriate to > sensible descriptions of visual experience; the dimensional factoring > through which Euclid created his cognitive or rational spacial reckonings. > This is clearly evidenced by the insistence of all physicists and > mathematicians who claim that we cannot 'fold' time and space into rate. Seeing is believing ... show me! (OK, it's in the full paper.) A good physicist will believe anything that makes life simpler; it's only *mathematicians* that insist on rigorously and blindly following their forebears. Of course, I'm a bit cynical on this one (geez, if I weren't, I'd be believing in all sorts of things like perpetuum mobiles and cold fusion), but willing to listen to a good argument. > FURTHER COMMENTS WHICH WILL HELP ALL WHO HAVE READ THIS ONGOING DISCUSSION [More details on binocular field projection] Again, these paragraphs *sound*, at first, like pseudo-scientific ramblings to people working with physics jargon every day. However, I am beginning to understand what Tom is on about. It sounds good. It sounds very good, in fact. But a warning to science-people: you have to translate his jargon a bit to fit your own jargonology. Maybe I'll convert him yet. > I intend to support this discussion further by posting a portion of my > manuscript with the appropriate images to virtu-l archives as soon as I can. Yeah, gimme, gimme. :) I need some good pictures to get this straight. John ---------------------------------------------------------------------------- John P. Costella School of Physics, The University of Melbourne jpc@tauon.ph.unimelb.edu.au Tel: +61 3 543-7795, Fax: +61 3 347-4783 ----------------------------------------------------------------------------