[net.games.frp] Infravision from a physical point of view

tgm@ukc.UUCP (T.Murphy) (03/10/85)

             I have had many arguments with my  players  as  to  the
        effect  and use of infravision.  I use the strict definition
        ``infravision is the ability to see into the infrared  spec-
        trum.''  (Players  Handbook 102).  Sadly, given this defini-
        tion Gygax goes on and imposes all sorts of rules bearing no
        basis  on this physical supposition.  Effecively infravision
        is just another colour.  The normal human eye can see in the
        electromagnetic  spectrum  from red to violet so extend this
        to from infra-red to (possibly ultra-) violet.  Things  like
        ``switching''  infravision on and off and ``concentrating on
        infravision'' and `letting your  eyes  adjust''  just  don't
        make  sense.   Your  eyes  adjust to the dark because of the
        difference in brightness, not colour.  (Just a  minute,  let
        my eyes adjust so that I can admire the blue wallpaper) Bear
        in mind that the human body with normal  clothes  on  (which
        doesn't  make  much  difference  anyway)  radiates  as  much
        infra-red light  as  a  80-watt  lightbulb  radiates  normal
        light.   You  must make the distinction that it the heat and
        not the light of a torch that spoils  infravision.   So  the
        old  trick of casting continual light on a stone and hanging
        it in a lantern should work  without  spoiling  infravision.
        Perhaps  the  most  inconceived  idea  of infravision was in
        ``Vault of the Drow'' by the great Gygax where there existed
        clocks that ``glowed green in infravision''.
        
             Just a note:  both  invisibility  and  darkness  cancel
        infravision.

                        mcvax!ukc!tcdmath!jaymin
Joe Jaquinta, c/o D.U. Mathematical Society, Trinity College Dublin, Ireland

euren@ttds.UUCP (Leif Euren) (03/14/85)

Joe Jaquinta writes:
>Effecively infravision is just another colour. The normal human eye can
>see in the electromagnetic spectrum from red to violet so extend this
>to from infra-red to (possibly ultra-) violet. Things like ``switching''
>Infravision and off and ``concentrating on infravision'' and `letting
>your eyes adjust'' just don't make sense.  Your eyes adjust to the dark
>because of the difference in brightness, not colour.

As far as I know, the human retina contains of two kinds of
light-sensitive cells (I can't get their correct english names, but
let's call them `rods' and `taps'), of which the taps `come in three
colours' but are less sensitive. Should one give a physiological
explanation to infra-vision, I'm tempted to assign it to the more
sensitive rods. As everybody knows, it takes 10-20 minutes to aquire
night vision (changing from taps to rods), but a mere instant to
destroy it (changing back). With this explanation, Gygax is right.


>The old trick of casting continual light on a stone and hanging it in a
>lantern should work without spoiling infravision.

According to what's said above, it shouldn't.


Of course, it's completely ridiculous to give scientific explanations
to fantasy concepts. And what do we know about elven physiology?  In
the AD&D universe I'm Mastering, seeing comes from the sight-beams
emanating from each persons eyes (thats why you sometimes can feel if
someone is looking at you), and even then I discourage my players to
use their infra-vision. It hasn't been useful to them, anyway.

>Just a note: both invisibility and darkness cancel infravision.

In any case, you are right about this!
=	=	=	=	=	=	=	=	=	=
	Real Life:	Leif Euren
	Fantasy	:	Herven (Fighter), Siegfried (Assassin)
	Usenet	:	enea!ttds!euren

berosetti@watrose.UUCP (Barry Rosetti) (03/18/85)

> 
> Of course, it's completely ridiculous to give scientific explanations
> to fantasy concepts. And what do we know about elven physiology?  In
> the AD&D universe I'm Mastering, seeing comes from the sight-beams
> emanating from each persons eyes (thats why you sometimes can feel if
> someone is looking at you), and even then I discourage my players to
> use their infra-vision. It hasn't been useful to them, anyway.
> 
  I don't think that it's rediculous to give scientific exlanations.
  As a matter of fact, if you can come up with a feasible explanation
  for a novel phenomena (sp?) you will know a lot better how to react
  to various twists and unexpected actions on the part of the players 
  (as far as the phenomena is concerned).
   
  In my campaign, I developed a new race (the Dwundel).  These creatures
  started off as humans and half-elves but were corrupted by a high
  devil called Trintur (son of Glasya and Mammon).  Their blood was mixed
  through eons with various different kinds of devils and the like.
  As a result of this and high magicks, they developed extended abilities
  and resistances, with those of the lower types of devils as base.  Included
  in these abilities is a 'special' infra-vision which is described as
  follows:

     (0) Infra-red light is just another spectrum of light.  It is not
	 solely associated with heat, however hot objects act much as 
	 a night light since heat gives off a limited amount of infra-red
	 light.

     (1) The sides of the Dwundel's eyes enamate a frequency of light in the 
	 infra-red spectrum.  Their sensitive pupils collect any reflecting
	 light and thus they can 'see' much as a bat can 'see' whenever there
	 is a total lack of infra-red light (or a great diminishing thereof).
	 A membrane over their pupils screens the amount of light that reaches
	 the sensitive areas (ie. the conterpart of rods and 'cones' in humans).
	 Thus, they always have some sort of light (of relatively
	 consistant intensity) and they are seldom blinded by a burst 
	 of infra-red light.

     (2) The Dwundel's eyes are NOT hot.  The light they enamate is IR but
	 as I said above IR light is just another form of light and not 
	 strictly associated with heat.

     (3) The Dwundel have no sensitivity to any of our 'normal' light.  This
	 is because of their specific breeding, magicks, etc.

  This background for their sight gives me the ability to handle strange
  situations (ie. a control temperature at a range of greater than 60' (the
  range of the light their eyes enamate) will give those within practical
  invisibility, but any closer the light from their eyes falls upon the sphere
  and spots something wrong).  A scientific explanation (or nearly scientific)
  provides  the ability to reason about something, and you don't have to 
  rely on an enumerated set of rules like (if xx then yy).
    
		    Barry Rosetti
		    ( ..!watdcsu!watrose!berosetti)
 
  "When in trouble, scream and shout, run in panic, jump about.."
	 - Heinlien (sp?)

moroney@jon.DEC (Mike Moroney) (03/19/85)

>Effecively infravision is just another colour. The normal human eye can
>see in the electromagnetic spectrum from red to violet so extend this
>to from infra-red to (possibly ultra-) violet. Things like ``switching''
>Infravision and off and ``concentrating on infravision'' and `letting
>your eyes adjust'' just don't make sense.  Your eyes adjust to the dark
>because of the difference in brightness, not colour.

Not exactly true.  In the human eye, the sensitivity to color IS dependant
on the amount of available light.  When it gets dark enough, the color
sensing portion of the eye doesn't have enough light to operate and we lose
our ability to differentiate colors and we see in black and white.  Not
only that, the low-light sensing portion of the eye cannot sense red, so
in the dark, humans lose ALL ability to sense red.  If you don't believe me,
take some bright red object into a dark room with you and look at it. What
color does it look like?  That's right, BLACK as COAL.  As far as the eye is
concerned, it isn't reflecting any light in the visible range.  Granted, this
is the exact opposite of what infravision is described as, so it's a little
confusing.

>The old trick of casting continual light on a stone and hanging it in a
>lantern should work without spoiling infravision.

Not necessarily.  Imagine one of those "glow-in-the-dark" toys that glow
green in the dark.  In normal light, they appear white from the reflected
light, even though they are still glowing.  If infravision worked the same way,
it is possible normal light could overpower it, especially if the elven eye
was BARELY sensitive to infrared.  That makes some sense, since infravision is
only good to 60-90 feet, and the bodies being sensed are as bright as a 100 watt
light bulb in the infrared.

"There's a madness to my method."			Mike Moroney
						..decwrl!rhea!jon!moroney