 |
|
|
|
|
|
| |
| |
|
|
|
|
| |
| |
|
|
In article <3eba0c14$1@news.povray.org>,
"Andrew Coppin" <orp### [at] btinternet com> wrote:
> OK, well, a lump of shashed up ice doesn't look reflective at all...
Ice is very reflective. That's why you can see it.
--
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Christopher James Huff <cja### [at] earthlinknet> wrote:
> Mirages. The varying density can cause reflections.
You don't mean variable refraction?
--
#macro M(A,N,D,L)plane{-z,-9pigment{mandel L*9translate N color_map{[0rgb x]
[1rgb 9]}scale<D,D*3D>*1e3}rotate y*A*8}#end M(-3<1.206434.28623>70,7)M(
-1<.7438.1795>1,20)M(1<.77595.13699>30,20)M(3<.75923.07145>80,99)// - Warp -
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
In article <3ebbd2fb@news.povray.org>, Warp <war### [at] tagpovrayorg>
wrote:
> > Mirages. The varying density can cause reflections.
>
> You don't mean variable refraction?
I do, and don't. The varying density causes varying optical density,
which produces variable refraction. If things are set up properly, you
can end up with reflections from a layer of hot air which look a lot
like water.
--
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
> Is it possible for a transparent substance to be non-reflective? Or are
all
> transparent substances inherantly reflective to a certain degree?
Every transparent substance is reflective and is not.
If you are in water, a glass with ior of water won't reflect anything.
If you have an interface, it's reflection, if you have a gradient of ior
(like hot air on the road), you have some refraction.
That's all.
Now, try to think about a relation between ior and reflectivity...
selsek
new feature requested: auto_reflection :-))
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
> On desert you can see images in the air. You know how ?
> http://www.islandnet.com/~see/weather/graphics/photos/supmirag.gif
On hot roads too, you know...
It's an ior gradient.
You can easily reproduce this phnomenon in pov... and get max_trace_level
very high. (you put boxes with progressive ior and check the result).
selsek
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
On Wed, 07 May 2003 15:26:48 -0400, Andrew Coppin wrote:
> Here's a simple enough question...
>
> Is it possible for a transparent substance to be non-reflective? Or are
> all transparent substances inherantly reflective to a certain degree?
If you work at it hard enough ... If you look at it as an impedance
mismatch causing the reflection then you can layer materials on a surface
which "match" the impedance of air to glass. That gives a number of
smaller reflections which sum to less than the single reflection without
them. That is all the anti-reflection coatings do on lenses.
If you could apply a single layer that smoothly transitioned the IOR from
air to glass you would theoretically have no reflection as there would not be a
point of different IORs -- unless a low pressure front moves in or the
humidity changes.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
On Thu, 08 May 2003 06:17:03 -0400, Warp wrote:
> Andrew <ast### [at] hotmailcom> wrote:
>> If something was truly non-reflective, it would be perfectly invisible
>
> A transparent object which refracts light is never invisible.
Observable and invisible are different things. A gravitational lens is
invisible but observable. The hot air over a road is invisible but
observable by the turbulent distortion.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
On Wed, 07 May 2003 15:26:48 -0400, Andrew Coppin wrote:
> Here's a simple enough question...
>
> Is it possible for a transparent substance to be non-reflective? Or are
> all transparent substances inherantly reflective to a certain degree?
>
Also the turbulent hot air over a road in summer is an example of
smoothly varying IOR that does not in itself reflect. We cannot see the
turbulence whorls themselves as they do not reflect because of the
smoothly varying IOR.
The shallow angle mirage is somewhat different phenomenon.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
On Thu, 08 May 2003 03:48:09 -0400, Andrew Coppin wrote:
> OK, well, a lump of shashed up ice doesn't look reflective at all... but
> take a bit and polish it to give it a nice smooth surface and you find
> that it actually IS reflective. Was thinking, if you have a layer of
> gas, it's surface probably isn't smooth, which might explain why it
> doesn't look reflective.
>
> If that makes sense.
>
Smoothed up it is specular reflection which is a special case of
reflection. The gas has a smoothly varying IOR so it does not have a
reflective surface.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
On Tue, 13 May 2003 17:02:50 -0400, selsek wrote:
>> On desert you can see images in the air. You know how ?
>> http://www.islandnet.com/~see/weather/graphics/photos/supmirag.gif
>
> On hot roads too, you know...
> It's an ior gradient.
> You can easily reproduce this phnomenon in pov... and get
> max_trace_level very high. (you put boxes with progressive ior and check
> the result).
>
Shallow angle reflection is a different issue. A sheet of glass is
totally reflective at a shallow angle.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
