Hi there !
I use 25 successive transparent boxes with different IOR's to simulate a
desert mirage ... The problem I get is that although I set transmit 1 I
have a vast diminuition in light intensity.
I would appreciate any piece of advice you got! If i haven't stated the
problem clear enough, please ask !
Thanx a lot,
Redjack

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Redjack <nomail@nomail> wrote:
> I use 25 successive transparent boxes with different IOR's to simulate a
> desert mirage ... The problem I get is that although I set transmit 1 I
> have a vast diminuition in light intensity.
> I would appreciate any piece of advice you got! If i haven't stated the

  That was one of the first (if not the first) entry added to the Q&T page:

http://tag.povray.org/povQandT/languageQandT.html#maxtracelevel

-- 
#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 -

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Redjack wrote:
> Hi there !
> I use 25 successive transparent boxes with different IOR's to simulate a
> desert mirage ... The problem I get is that although I set transmit 1 I
> have a vast diminuition in light intensity.
> I would appreciate any piece of advice you got! If i haven't stated the
> problem clear enough, please ask !
> Thanx a lot,
> Redjack
> 
> 

without knowing the details of your .pov code, it is hard to say
exactly what the cause of this problem could be ... but a hunch
tells me you might want to increase the max_trace_level seitting
in your global_settings block.

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bob <roc### [at] almostbestwebnet> wrote:
> Redjack wrote:
> > Hi there !
> > I use 25 successive transparent boxes with different IOR's to simulate a
> > desert mirage ... The problem I get is that although I set transmit 1 I
> > have a vast diminuition in light intensity.
> > I would appreciate any piece of advice you got! If i haven't stated the
> > problem clear enough, please ask !
> > Thanx a lot,
> > Redjack
> >
> >
>
> without knowing the details of your .pov code, it is hard to say
> exactly what the cause of this problem could be ... but a hunch
> tells me you might want to increase the max_trace_level seitting
> in your global_settings block.

Thank you guys for your stunning speed of response :)

I have read that one in the FAQ, but it is not the problem I got.
Actually, I have max_trace_level 256 which is the maximum (and even
adc_bailout 0) ...

The important piece of code is the following:

#declare Counter=0;
#while(Counter<25)
box{
<-40,-1-(Counter+1)*0.8,3>,<40,-1-Counter*0.8,-20>
texture{pigment{transmit 1}}
interior{ior 1.5-0.005*Counter
photons{target collect off refraction on reflection on}
}
#declare Counter=Counter+1;
#end

As to my understanding, I should be creating 25 0.8 units thick boxes lying
on top of each other. The ray should pass through each of them, being bent
successively. There should be no intensity loss due to transmit 1 ... that
is what I have been thinking... :)
Do you have an idea what could have gone wrong ?

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Redjack wrote:
> #declare Counter=0;
> #while(Counter<25)
> box{
> <-40,-1-(Counter+1)*0.8,3>,<40,-1-Counter*0.8,-20>

This gives you coincident surfaces, since the front of one box is at the 
same place as the back of the next.

> As to my understanding, I should be creating 25 0.8
> units thick boxes lying on top of each other.

Correct, but you have to make a tiny gab between them to avoid coincident 
surfaces. :)

Rune
-- 
3D images and anims, include files, tutorials and more:
rune|vision:  http://runevision.com
POV-Ray Ring: http://webring.povray.co.uk

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"Rune" <run### [at] runevisioncom> wrote:
> Redjack wrote:
> > #declare Counter=0;
> > #while(Counter<25)
> > box{
> > <-40,-1-(Counter+1)*0.8,3>,<40,-1-Counter*0.8,-20>
>
> This gives you coincident surfaces, since the front of one box is at the
> same place as the back of the next.
>
> > As to my understanding, I should be creating 25 0.8
> > units thick boxes lying on top of each other.
>
> Correct, but you have to make a tiny gab between them to avoid coincident
> surfaces. :)
>
> Rune
> --
> 3D images and anims, include files, tutorials and more:
> rune|vision:  http://runevision.com
> POV-Ray Ring: http://webring.povray.co.uk

Now that should settle it :) Thanks a lot ! I'll try this evening and report
my success (or not ;))

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"Redjack" <nomail@nomail> wrote:
> Now that should settle it :) Thanks a lot ! I'll try this evening and report
> my success (or not ;))

It doesn't work! I don't know what to do now ... I'll post my complete
source code now, so that if you are able to spare the time, you could look
for errors in my architecture:

#include "colors.inc"
#include "woods.inc"
#include "stones.inc"

global_settings{max_trace_level 256 adc_bailout 0 photons{count 50000
autostop 0}}

camera{location <0,0,-20> look_at <0,0,0>}
light_source{<0,1,-10> color White fade_power 0}

//Yellow Cone : the Mirage-Object
cone{<0,0.5,0>,2,<0,3,0>,0 texture{pigment{Yellow}} photons{target
reflection on} no_shadow}

merge{
box{<-40,-3.5,3>,<40,-3.01,-20> texture {T_Wood19} photons{target reflection
on}}
box{<-20,-3.01,3>,<20,20,3.5> texture{T_Grnt3} photons{target reflection
on}}
}

//Generates the Refraction-Slices
#declare Counter=0;
#declare Steps=25;
#declare n0=1;
#declare n1=0.94;
#declare deltan=(n0-n1)/Steps;
#declare h=3;
#declare deltah=h/Steps;
#declare y0=-3+h;

union{
#while(Counter<Steps)
box{<-40,y0-(Counter+1)*deltah,2.99>,<40,y0-Counter*deltah-0.01,-20>
texture{pigment{transmit 1}}
interior{ior n0-deltan*Counter} photons{target collect off refraction on}}
#declare Counter=Counter+1;
#end
}

As you can see if you render it, the refracted mirage images are already ...
recognizable :|, but the floor at the bottom is so dark and I don't know
why !

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Redjack wrote:

> "Redjack" <nomail@nomail> wrote:
> 
>>Now that should settle it :) Thanks a lot ! I'll try this evening and report
>>my success (or not ;))
> 
> 
> It doesn't work! I don't know what to do now ... I'll post my complete
> source code now, so that if you are able to spare the time, you could look
> for errors in my architecture:
> 
<snipped>
> As you can see if you render it, the refracted mirage images are already ...
> recognizable :|, but the floor at the bottom is so dark and I don't know
> why !
> 
> 

I think your problem has to do with photons. When I disable them in your 
code, I get the result I think you expect... But I'm afraid I don't know 
what you could do in order to use photons...
I might be having a similar problem, trying to render a big metallic 
blob on a white floor. The floor turns black in certain cases, and I 
don't know why...

Sorry for not having a more helpful answer :-(

-- 
Vincent

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Vincent LE CHEVALIER <lec### [at] ctiecpfr> wrote:
> Redjack wrote:
>
> > "Redjack" <nomail@nomail> wrote:
> >
> >>Now that should settle it :) Thanks a lot ! I'll try this evening and report
> >>my success (or not ;))
> >
> >
> > It doesn't work! I don't know what to do now ... I'll post my complete
> > source code now, so that if you are able to spare the time, you could look
> > for errors in my architecture:
> >
> <snipped>
> > As you can see if you render it, the refracted mirage images are already ...
> > recognizable :|, but the floor at the bottom is so dark and I don't know
> > why !
> >
> >
>
> I think your problem has to do with photons. When I disable them in your
> code, I get the result I think you expect... But I'm afraid I don't know
> what you could do in order to use photons...
> I might be having a similar problem, trying to render a big metallic
> blob on a white floor. The floor turns black in certain cases, and I
> don't know why...
>
> Sorry for not having a more helpful answer :-(
>
> --
> Vincent

That already is a great answer for the simple reason that it works :) Screw
photons - all I want is a bright floor ;)
Thanks a lot for helping y'all!

(Nevertheless, I must say, that POV-Ray is not very convenient for
simulating that mirage phenomenon (Although I don't know if other
raytracers are better...))

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Redjack wrote:
!
> 
> (Nevertheless, I must say, that POV-Ray is not very convenient for
> simulating that mirage phenomenon (Although I don't know if other
> raytracers are better...))

Heven't read the entire thread, but POV-Ray should have an easy time 
with the mirage phenomenon. Try variable reflection if you haven't yet.

  -Shay

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