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  three tests about pov (Message 1 to 5 of 5)  
From: CAS
Subject: three tests about pov
Date: 25 Aug 2014 05:55:02
Message: <web.53fb07d1863420e26a92a3a00@news.povray.org>
I am a student.Recently I need to do three tests about POV. And I have done
three tests,but I do not know whether they are right.I beg a hot help me check.
Requirements:
1,Raytracing the scene using no illumination source and distinct color settings
for each object representing different materials results in an image which can
be converted to a materials map M(x,y) by simple classification of the red,green
and blue channel images produced by the raytracer.A sample is shown in Fig. 2 on
the left.
2,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). A sample is
shown in Fig. 2 center.
3,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)

of NoShade(x,y) is shown in Fig.2 on the right.
I have done three tests.Beg somebody have a check .Besides,about the third
test,I could not find the option of turning off mutual shadowing between
objects.So the result is the same as test 2.I know something wrong with
test3.How can I modify my codes?Whether codes about tests meet above three
requirements?beg a hot .Great gratitude and best wishes!


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Attachments:
Download 'three tests.zip' (2273 KB)

From: Bald Eagle
Subject: Re: three tests about pov
Date: 25 Aug 2014 10:40:01
Message: <web.53fb4a66bad06435e7df57c0@news.povray.org>
I'm not sure exactly what you're trying to do, although I kind of get the idea
from the manual/textbook scan you posted.

> 1,Raytracing the scene using no illumination source and distinct color settings
> for each object representing different materials results in an image which can
> be converted to a materials map M(x,y) by simple classification of the red,green
> and blue channel images produced by the raytracer.A sample is shown in Fig. 2 on
> the left.

in "test1M(x,y)\pov1.pov"  I see you are only giving your object a pigment.  If
I understand the goal, you need to use the .red, .green, and .blue components of
the initially rendered image as data for a material map.
I don't see where you have defined a material map in the .pov file.

hit F1 in POV-Ray and look up "material_map" in the index.

> 2,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). A sample is
> shown in Fig. 2 center.


> 3,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)

> of NoShade(x,y) is shown in Fig.2 on the right.

I'm lost with this and can't help you.  I've never done anything like that
before.   Maybe someone else can figure this out, or your instructor can explain
it better.

If you have more information, or a reference with more details, maybe I could
offer a suggestion.


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From: clipka
Subject: Re: three tests about pov
Date: 25 Aug 2014 10:59:07
Message: <53fb4f3b$1@news.povray.org>
Am 25.08.2014 11:54, schrieb CAS:
> I am a student.Recently I need to do three tests about POV. And I have done
> three tests,but I do not know whether they are right.I beg a hot help me check.
> Requirements:
> 1,Raytracing the scene using no illumination source and distinct color settings
> for each object representing different materials results in an image which can
> be converted to a materials map M(x,y) by simple classification of the red,green
> and blue channel images produced by the raytracer.A sample is shown in Fig. 2 on
> the left.
> 2,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). A sample is
> shown in Fig. 2 center.
> 3,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)

> of NoShade(x,y) is shown in Fig.2 on the right.
> I have done three tests.Beg somebody have a check .Besides,about the third
> test,I could not find the option of turning off mutual shadowing between
> objects.So the result is the same as test 2.I know something wrong with
> test3.How can I modify my codes?Whether codes about tests meet above three
> requirements?beg a hot .Great gratitude and best wishes!

I think one of us has entirely misunderstood the assignment...  it looks 
like you're using POV-Ray just as a "viewer" for some crude greyscale 
image format consisting of pixel coordinates in a "pov-xyz.txt" file and 
pixel brightness in a "pov-ref.txt" file.

That's quite an interesting use of the POV-Ray scene description 
language, but I'm quite sure that's not at all what your teacher had in 
mind.


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From: Jaime Vives Piqueres
Subject: Re: three tests about pov
Date: 25 Aug 2014 12:15:07
Message: <53fb610b$1@news.povray.org>

> I am a student.Recently I need to do three tests about POV. And I have done
> three tests,but I do not know whether they are right.I beg a hot help me check.
> Requirements:
> 1,Raytracing the scene using no illumination source and distinct color settings
> for each object representing different materials results in an image which can
> be converted to a materials map M(x,y) by simple classification of the red,green
> and blue channel images produced by the raytracer.A sample is shown in Fig. 2 on
> the left.
> 2,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). A sample is
> shown in Fig. 2 center.
> 3,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)

> of NoShade(x,y) is shown in Fig.2 on the right.
> I have done three tests.Beg somebody have a check .Besides,about the third
> test,I could not find the option of turning off mutual shadowing between
> objects.So the result is the same as test 2.I know something wrong with
> test3.How can I modify my codes?Whether codes about tests meet above three
> requirements?beg a hot .Great gratitude and best wishes!

   I've no idea what all this is about, but if your problem is disabling 
the shadowing, just ad "no_shadow" to your objects, as it has been said 
already.

--
jaime


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From: CAS
Subject: Re: three tests about pov
Date: 26 Aug 2014 02:40:01
Message: <web.53fc2aaebad06436a92a3a00@news.povray.org>
Jaime Vives Piqueres <jai### [at] ignoranciaorg> wrote:

> > I am a student.Recently I need to do three tests about POV. And I have done
> > three tests,but I do not know whether they are right.I beg a hot help me check.
> > Requirements:
> > 1,Raytracing the scene using no illumination source and distinct color settings
> > for each object representing different materials results in an image which can
> > be converted to a materials map M(x,y) by simple classification of the red,green
> > and blue channel images produced by the raytracer.A sample is shown in Fig. 2 on
> > the left.
> > 2,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). A sample is
> > shown in Fig. 2 center.
> > 3,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)

> > of NoShade(x,y) is shown in Fig.2 on the right.
> > I have done three tests.Beg somebody have a check .Besides,about the third
> > test,I could not find the option of turning off mutual shadowing between
> > objects.So the result is the same as test 2.I know something wrong with
> > test3.How can I modify my codes?Whether codes about tests meet above three
> > requirements?beg a hot .Great gratitude and best wishes!
>
>    I've no idea what all this is about, but if your problem is disabling
> the shadowing, just ad "no_shadow" to your objects, as it has been said
> already.
>
> --
> jaime

Test2 is the same as test3,and the only difference is test3 consider the shadow
of the objects themselves,not consider the mutual shadow between objects.Test3
added noshaow in objects.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(the above code is wrong,download this one),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)

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