Jan Dvorak nous apporta ses lumieres en ce 2008/02/19 07:39:
> Sven Littkowski napsal(a):
>> Hi,
>>
>> who can consult me? I want to create a scene named "The Magnificent 
>> men in their Flying Machines", which contains a number of wicked 
>> airplanes and want-to-be-airplanes. Most of them have canvas over the 
>> wooden framework.
>>
>> While I have already a graphic file I can use for the canvas texture, 
>> I am still in need of some consulting: the cancvas you get to see on 
>> vintage airplanes is slightly transluscent, means, if you see such an 
>> airplane in the air and you're below it, through the sunlight you can 
>> get an idea of the wooden framework below the canvas. I need your 
>> advices how best to achieve such an effect. To make it even a bit more 
>> difficult, the canvas seems to blur the edges of the wooden framwork 
>> below it, in its slightly transluscent effect. How to achieve that 
>> little blur effect?
>>
>> Thanks,
>>
>> Sven
>>
> use a blurred refraction:
> -make it solid
> -give it IOR
> -use multiple pigment{Clear} normal{bumps} layers
Don't use to many, each ray will be affected by two surfaces.
> -add the canvas itself
> 
> It's slow but it might work


-- 
Alain
-------------------------------------------------
But I thought YOU did the backups...

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Thanks, Jan and Alain! I appreciate your help a lot!

I use POV-Ray since around 1993 or so. Long time. But I used, up to now, 
only relatively simple techniques. I would like to ask you two to give me 
some sample code for a basic box, which should have these attributes. The 
reason is, I was reading your suggestions but still don't know, how to 
follow them up.

Let it be a thin sample box, resembling some canvas:

box
{
 < 0.0, 0.0, 0.0 > < 0.0, 0.0, 0.0 >
 ...
}

Let's assume the the name for the canvas texture graphic file would be 
"Canvas.png".

Thanks for your help again,

Sven





"Sven Littkowski" <sven [] jamaica-focus [] com> schrieb im Newsbeitrag 
news:47baa43d$1@news.povray.org...
> Hi,
>
> who can consult me? I want to create a scene named "The Magnificent men in 
> their Flying Machines", which contains a number of wicked airplanes and 
> want-to-be-airplanes. Most of them have canvas over the wooden framework.
>
> While I have already a graphic file I can use for the canvas texture, I am 
> still in need of some consulting: the cancvas you get to see on vintage 
> airplanes is slightly transluscent, means, if you see such an airplane in 
> the air and you're below it, through the sunlight you can get an idea of 
> the wooden framework below the canvas. I need your advices how best to 
> achieve such an effect. To make it even a bit more difficult, the canvas 
> seems to blur the edges of the wooden framwork below it, in its slightly 
> transluscent effect. How to achieve that little blur effect?
>
> Thanks,
>
> Sven
>

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Sven Littkowski escribió:
> Let it be a thin sample box, resembling some canvas:
> 
> box
> {
>  < 0.0, 0.0, 0.0 > < 0.0, 0.0, 0.0 >
>  ...
 > }

That is a zero-sized box. An invisible point.

Post a reply to this message

Thanks, Jan, Nicolas and Alain! I appreciate your help a lot!

I use POV-Ray since around 1993 or so. Long time. But I used, up to now,
only relatively simple techniques. I would like to ask you two to give me
some sample code for a basic box, which should have these attributes. The
reason is, I was reading your suggestions but still don't know, how to
follow them up.

Let it be a thin sample box, resembling some canvas (corrected version):

box
{
 < -10.0, -1.0, 0.0 > < 10.0, 1.0, 0.005 >
 ...
}

Let's assume the the name for the canvas texture graphic file would be
"Canvas.png".

Thanks for your help again,

Sven

Post a reply to this message

Sven Littkowski napsal(a):
> Thanks, Jan, Nicolas and Alain! I appreciate your help a lot!
> 
> I use POV-Ray since around 1993 or so. Long time. But I used, up to now,
> only relatively simple techniques. I would like to ask you two to give me
> some sample code for a basic box, which should have these attributes. The
> reason is, I was reading your suggestions but still don't know, how to
> follow them up.
> 
> Let it be a thin sample box, resembling some canvas (corrected version):
> 
> box
> {
>  < -10.0, -1.0, 0.0 > < 10.0, 1.0, 0.005 >
>  ...
> }
> 
> Let's assume the the name for the canvas texture graphic file would be
> "Canvas.png".
> 
> Thanks for your help again,
> 
> Sven
> 
> 
> 
see http://tag.povray.org/povQandT/languageQandT.html#blurredreflection
I haven't tried it myself but I could if you want me to.

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>> -use multiple pigment{Clear} normal{bumps} layers
> Don't use to many, each ray will be affected by two surfaces.
to be exact, the times don't add up. they multiply.

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Jan, it might be I have to ask you to give me a sample canvas. I was reading 
the link you provided, but this all sounds a bit Chinese to me. I never used 
those techniques before, not even the NORMAL feature.

All I know is, that I would go for the small scale (0.001), since I need a 
high antialiasing and a high speed.

Thanks a lot, I appreciate your help very much! Shall I name one of these 
wicked vintage airplanes with your name?

Here the canvas box and a thin wooden board behind.

box
{
  < -10.0, -1.0, 0.0 > < 10.0, 1.0, 0.005 >
  ...
}

box
{
  < -10.0, -0.025, 0.005 > < 10.0, 0.025, 0.055 >
  ...
}

Greetings,

Sven






"Jan Dvorak" <jan### [at] centrumcz> schrieb im Newsbeitrag 
news:47bb4f1f@news.povray.org...
> Sven Littkowski napsal(a):
>> Thanks, Jan, Nicolas and Alain! I appreciate your help a lot!
>>
>> I use POV-Ray since around 1993 or so. Long time. But I used, up to now,
>> only relatively simple techniques. I would like to ask you two to give me
>> some sample code for a basic box, which should have these attributes. The
>> reason is, I was reading your suggestions but still don't know, how to
>> follow them up.
>>
>> Let it be a thin sample box, resembling some canvas (corrected version):
>>
>> box
>> {
>>  < -10.0, -1.0, 0.0 > < 10.0, 1.0, 0.005 >
>>  ...
>> }
>>
>> Let's assume the the name for the canvas texture graphic file would be
>> "Canvas.png".
>>
>> Thanks for your help again,
>>
>> Sven
>>
>>
>>
> see http://tag.povray.org/povQandT/languageQandT.html#blurredreflection
> I haven't tried it myself but I could if you want me to.

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Correction: here it is again. Just the upper box needs to be modified.

box   // Canvas
{
  < -10.0, -1.0, 0.0 > < 10.0, 1.0, 0.005 >
  ...
}

box   // Wooden Frame
{
  < -10.0, -0.025, 0.005 > < 10.0, 0.025, 0.055 >
 pigment {  Brown }
}

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Probably something like this...

#declare canvas = texture {
   pigment {
      image_map {
         png "star_arrow.png"
         transmit all 0.35
      }
      rotate 90*x
   }
   normal {
      bump_map {
         png "canvas.png"
         interpolate 2
      }
      rotate 90*x
      scale 4
   }
   finish {
      specular 0.3
      roughness 0.05
   }
};

http://s201.photobucket.com/albums/aa280/Zakardis/?action=view&current=cloth_wing.png
http://s201.photobucket.com/albums/aa280/Zakardis/?action=view&current=star_arrow.png
http://s201.photobucket.com/albums/aa280/Zakardis/?action=view&current=canvas.png

It'll look a bit better with radiosity too,
since the color of the ribs will color the canvas.

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Thanks for the code, Tim!

I am posting someimages in the Binaries.Images group, to show what I have in 
mind.

Sven


"Tim Attwood" <tim### [at] comcastnet> schrieb im Newsbeitrag 
news:47bb889b$1@news.povray.org...
> Probably something like this...
>
> #declare canvas = texture {
>   pigment {
>      image_map {
>         png "star_arrow.png"
>         transmit all 0.35
>      }
>      rotate 90*x
>   }
>   normal {
>      bump_map {
>         png "canvas.png"
>         interpolate 2
>      }
>      rotate 90*x
>      scale 4
>   }
>   finish {
>      specular 0.3
>      roughness 0.05
>   }
> };
>
>
http://s201.photobucket.com/albums/aa280/Zakardis/?action=view&current=cloth_wing.png
>
http://s201.photobucket.com/albums/aa280/Zakardis/?action=view&current=star_arrow.png
> http://s201.photobucket.com/albums/aa280/Zakardis/?action=view&current=canvas.png
>
> It'll look a bit better with radiosity too,
> since the color of the ribs will color the canvas.
>

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