|
 |
Chris Huff wrote in message ...
>In article <3a0efbd8@news.povray.org>, "Jan Walzer" <jan### [at] lzer net>
>wrote:
>> [New question:
>> what is with negative IOR
>
>Negative ior may not be unrealistic. The ior of a bubble of air in water
>is lower than the ior of water, it just makes the light bend the other
>way. An ior of 1 usually means no effect, because POV sets the ior of
>"space" to 1. It is the change in ior that causes light to bend...
Wrong. IOR is defined as the *ratio* of the speed of light in a given
material to a reference material (usually, the reference material is a hard
vacuum). Consequently, the IOR of a bubble of air in water is a value less
than 1 but greater than 0, if water is given an IOR of 1. If an object has
a negative IOR, it implies that light entering the object will have a
negative velocity -- it will enter the object, stop, turn around, and head
back the other direction!
--
Mark
Post a reply to this message
|
|
