Msg: 7039 *Conference*
04-01-97 15:39:04
From: RON WIESEN
To : TOM UPTON
Subj: REPLY TO MSG #7032 (SOL CENTRIC VIEW)
Thanks for the explanation Tom. From "Sol centric view" I thought the vantage point was at the Sun - now I know the vantage point is outside of the local neighborhood and old Sol is merely seen at center amid other stars. So the M100 screen portrays a view from an external vantage point - hey, it's your fantasy - why not. For an external view in 2-D, you fantasize that you're a space alien who is curious about our local neighborhood. By amazing coincidence the alien has two eyes like a human, and via binocular vision is thus capable of depth perception as we know it. My fantasy goes like this. To experience an external 3-D view of the local neighborhood, it's clear to me that the alien doing the viewing has physical dimensions that are... well, astronomic. Sort of like the '50s movie "Revenge of the 50 Foot Woman" but really really really scaled up. On this astronomic scale the alien is "close" because the distance between its eyes are an appreciable fraction of the Sun-to-alien distance, so the alien experiences a 3-D view. By amazing coincidence I image the alien has a nose midway between the eyes like a human. The nose is closer to the Sun than are each eye, so the nose is an interesting reference point. In my fantasy the alien is female with (most excellent) proportions like the woman in the movie - hey, it's my fantasy. With such proportions there are must be other interesting reference points with "shorter" Sun-to-alien distances than that of the nose - for example, her [ TEXT DELETED BY U.S. CENSOR SERVICE ] so close as to fill near regions of the local neighborhood. OK - the alien is "close and large" enough that from an internal vantage point, like the Sun, an image of the alien covers a lot of sky. I say the nose of the alien is the best reference point to develop the external 3-D view that the alien enjoys. Normalize the "Sun-to-alien-nose" distance at 1.0 units. Let each "alien-nose-to-eye" distance be 0.125 units, in other words an eye-to-eye baseline of 0.25 units. Limit the space volume of the local neighborhood to a radius of 0.1 units from the Sun. For 3-D simulation on the M100, as enjoyed by a human, this works out as: 1.5 inches is typical nose-to-eye distance for a human, thus 3 inches eye-to-eye 12 inches M100-to-nose, so 1 foot is the normalized unit of measure 1.2 inches radius scene on-screen for each eye to enjoy Not a bad fit to the M100 screen. The screen is 7.5 inch by 2. There is 3 inches between the center of the two scenes. With a 1.2 inch radius per scene then the "inner edges" of the scenes do not meet or overlap and remain apart by 0.6 inch. Horizontally, the 7.5 inch screen breaks out as: | 1.2 | 1.2 | 0.6 | 1.2 | 1.2 | 2.1 | <----- LEFT SCENE -----> <---- RIGHT SCENE -----> "nose" "excess part not used" Vertically, the 2.0 inch screen doesn't quite cover the 2.4 inch diameter height of the scenes. The top and bottom 0.2 inch portions do not appear - not so bad. I don't see where a matrix of elements is needed Tom. Just datum for star angular positions and distance is needed - I see no advantage to organizing data into an array of 3 dimensions. Every star (of your catalog) is seen from any of the external vantage points that can be taken (North, East-West at 0/90/180/270, and South). None are "candidates for exclusion" like in my prior message, so any simple datum structure works. Why not one list for your catalog with no particular order in the list? Based on the vantage point taken, the M100 does the math that projects two images of a star - a left eye scene projection and one for the right eye. The scenes differ a bit but that's 3-D. And why six particular vantage points? Why not let the alien orbit about, perhaps in a sphere restricted to maintaining a radius of 1 unit distance from old Sol, but otherwise free to enjoy various views. The trig formulas are the same - the angular position of the alien (the variable) is all that varies. Regarding an "extrafield dot" and how it appears, you're wasting your time on me Tom. Since birth I've never perceived depth via convergent binocular vision, so I can't appreciate how the extrafield appears and how it helps. I believe you - just can't experience it or imagine it myself. Although my eyes move for "convergence" at different distances like other folks, it's just a reflex action which happens to "look normal" to folks who observe me. I have monocular vision. My brain can not "sum" two simultaneous images into a 3-D impression, so it uses only the left image and ignores the right except for peripheral input. I don't run into things or have problems because I do perceive depth, but in a way you can't appreciate - no use explaining it. Amid the audience of a "well done" 3-D movie, all heads except mine jerk and duck in reaction to being "fooled" by what must seem like realistic 3-D motions to them. In rare everyday situations it's the other way around - I get "fooled" and react while others perceive nothing out of the ordinary.