POV-Ray : Newsgroups : povray.binaries.scene-files : some confusions about noshadow Server Time: 23 Jul 2019 11:01:43 GMT
  some confusions about noshadow (Message 1 to 3 of 3)  
From: CAS
Subject: some confusions about noshadow
Date: 27 Aug 2014 08:05:01
Message: <web.53fd8f80a78bcce46a92a3a00@news.povray.org>
Requirements:
pov2,Raytracing the scene with all diffuse surface reflectances set to unity and
no
ambient reflectances resulted in a 8-bit shading image Shade(x,y).

pov3,Generate a POV image NoShade(x,y) with the option of turning off mutual
shadowing between objects. The shadow map (0 for shadow and 1 for illumination)
is given by the difference Shadow(x,y) = (NoShade(x,y)—Shade(x,y))>0. A sample
of NoShade(x,y) is shown in Fig.2 on the right.

This pov2.pov is the same as pov3.pov,and the only difference is pov3.pov
consider the shadow of the objects themselves,not consider the mutual shadow
between objects.pov3.But I have a confuse:the difference map which is the result
of test3 minus test2 should be 0 or 1.However my difference map contains other
values apart from 0 and 1.
I do this two tests in order to judge the difference map pixel is in shadow or
in light.I want the output images differential is either 0 or 1, but the results
are not only 0 and 1,and also contain other results.Obviously it is wrong.Maybe
something wrong in test3 about turning off mutual shadow between objects.My
codes have uploaded,I beg somebody help me have a look and resolve this
problem.Thank you!


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Attachments:
Download 'two test2.zip' (1334 KB)

From: Jaime Vives Piqueres
Subject: Re: some confusions about noshadow
Date: 27 Aug 2014 09:09:58
Message: <53fda066@news.povray.org>
El 27/08/14 a las #4, CAS escribió:
> Requirements:
> pov2,Raytracing the scene with all diffuse surface reflectances set to unity and
> no
> ambient reflectances resulted in a 8-bit shading image Shade(x,y).
>
> pov3,Generate a POV image NoShade(x,y) with the option of turning off mutual
> shadowing between objects. The shadow map (0 for shadow and 1 for illumination)
> is given by the difference Shadow(x,y) = (NoShade(x,y)—Shade(x,y))>0. A sample
> of NoShade(x,y) is shown in Fig.2 on the right.
>
> This pov2.pov is the same as pov3.pov,and the only difference is pov3.pov
> consider the shadow of the objects themselves,not consider the mutual shadow
> between objects.pov3.But I have a confuse:the difference map which is the result
> of test3 minus test2 should be 0 or 1.However my difference map contains other
> values apart from 0 and 1.
> I do this two tests in order to judge the difference map pixel is in shadow or
> in light.I want the output images differential is either 0 or 1, but the results
> are not only 0 and 1,and also contain other results.Obviously it is wrong.Maybe
> something wrong in test3 about turning off mutual shadow between objects.My
> codes have uploaded,I beg somebody help me have a look and resolve this
> problem.Thank you!
>

   I think the result is correct... you are getting a value >0 where 
pixels are different, so

  Shadow(x,y) = (NoShade(x,y)—Shade(x,y))>0

   will give you the correct result... did you notice the >0 at the end?

--
jaime


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From: clipka
Subject: Re: some confusions about noshadow
Date: 27 Aug 2014 14:49:09
Message: <53fdefe5$1@news.povray.org>
Am 27.08.2014 09:57, schrieb CAS:
> Requirements:
> pov2,Raytracing the scene with all diffuse surface reflectances set to unity and
> no
> ambient reflectances resulted in a 8-bit shading image Shade(x,y).
>
> pov3,Generate a POV image NoShade(x,y) with the option of turning off mutual
> shadowing between objects. The shadow map (0 for shadow and 1 for illumination)
> is given by the difference Shadow(x,y) = (NoShade(x,y)—Shade(x,y))>0. A sample
> of NoShade(x,y) is shown in Fig.2 on the right.
>
> This pov2.pov is the same as pov3.pov,and the only difference is pov3.pov
> consider the shadow of the objects themselves,not consider the mutual shadow
> between objects.pov3.But I have a confuse:the difference map which is the result
> of test3 minus test2 should be 0 or 1.However my difference map contains other
> values apart from 0 and 1.
> I do this two tests in order to judge the difference map pixel is in shadow or
> in light.I want the output images differential is either 0 or 1, but the results
> are not only 0 and 1,and also contain other results.Obviously it is wrong.Maybe
> something wrong in test3 about turning off mutual shadow between objects.My
> codes have uploaded,I beg somebody help me have a look and resolve this
> problem.Thank you!

If I understand you correctly, what you want (or part of that) is an 
image where all illuminated surfaces are 100% white and all shadowed 
surfaces are 100% black.

To achieve this, use a "rgb 1" pigment and a "diffuse 1 brilliance 0 
ambient 0" finish.


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