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25 Dec 2024 23:46:08 EST (-0500)
  strange slant of objects in an ordinary scene (Message 1 to 7 of 7)  
From: krus
Subject: strange slant of objects in an ordinary scene
Date: 20 Aug 2002 18:55:06
Message: <web.3d62c85190bd25b72f4bd1e30@news.povray.org>
I'm in the proces of building my very first scene
The scene will be build on the skeleton below
Im not happy with the way the two flanking cylinders is posistioned on the
surface.
They seems to 'slant' or tilt outwards (left obj. tilts left and vis a vi)
The cylinder in the midle stands correct but why the distorsions in the
'margin'?

I'm afraid that the comments in the below code is in danish but they are
only reminders to my self

I would apreciate any help on why the cylinders are tilted and what i could
do to avoid that problem

regards krus

//code

Nu tages der hensyn til origin-hovedreglen
aug 02*/

#include "metals.inc"
//#include "stones.inc"


camera {
  location  <-1,6,-5>
  //right     x*image_width/image_height
  right 4/3*x
 up y
 //angle 50

  look_at   <0,2,0>
}



light_source {
  <-6, 0, -10>,
  color rgb <1,1,1>
}


// An area light (creates soft shadows)
// WARNING: This special light can significantly slow down rendering times!
light_source {
  0*x                 // light's position (translated below)
  color rgb 1.0       // light's color
  area_light
  <8, 0, 0> <0, 0, 8> // lights spread out across this distance (x * z)
  4, 4                // total number of lights in grid (4x*4z = 16 lights)
  adaptive 0          // 0,1,2,3...
  jitter              // adds random softening of light
  circular            // make the shape of the light circular
  orient              // orient light
  translate <40, 80, -40>   // <x y z> position of light
}


 plane {
    y, 0
    texture {
      pigment {
        checker
        color rgb<1, 1, 1>
        color rgb<0, 0, 0>
      }

    }
  }




//marker origin
cone { <0, 1, 0>, 0.0, <0, -1, 0>, 1.0
texture {
         T_Silver_3B

          }
          translate<0,0,0>
}

//-----------------------------------------------------------


#declare myCan=
union{


#declare canHeight=2.8;
cylinder {


  texture {
             T_Brass_3A

          }
          finish {ambient 0.2 diffuse 0.5
                specular .5
                roughness 1.05 // typical plastic appearance
                phong .6
                }










object {myCan
    //alt er defineret [flader scaleringer rotationer]
    //nu bliver det vist OG kan flyttes frit!
      translate<-2.9,0,1.5>

      }

object {myCan
      //translate<0,1.8,0>
      translate<0,0,3>
      }

object {myCan
      translate<3.1,0,0>
      }
//code-end


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From: Marc-Hendrik Bremer
Subject: Re: strange slant of objects in an ordinary scene
Date: 21 Aug 2002 04:26:51
Message: <3d634ecb@news.povray.org>
"krus" <nomail@nomail> schrieb im Newsbeitrag
news:web.3d62c85190bd25b72f4bd1e30@news.povray.org...
> They seems to 'slant' or tilt outwards (left obj. tilts left and vis a vi)
> The cylinder in the midle stands correct but why the distorsions in the
> 'margin'?

Your cylinders don't tilt, it's just a perspective distortion. Try narrowing
the 'angle' in your camera-settings and move the camera further away. Should
at least reduce your problem.

Regards,

Marc-Hendrik


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From: krus
Subject: Re: strange slant of objects in an ordinary scene
Date: 21 Aug 2002 08:30:05
Message: <web.3d6386dd9fcb6fdc2f4bd1e30@news.povray.org>
Marc-Hendrik Bremer wrote:
>"krus" <nomail[at]nomail> schrieb im Newsbeitrag
>news:web.3d62c85190bd25b72f4bd1e30[at]news.povray.org...
>> They seems to 'slant' or tilt outwards (left obj. tilts left and vis a vi)
>> The cylinder in the midle stands correct but why the distorsions in the
>> 'margin'?
>
>Your cylinders don't tilt, it's just a perspective distortion. Try narrowing
>the 'angle' in your camera-settings and move the camera further away. Should
>at least reduce your problem.
>
>Regards,
>
>Marc-Hendrik
>

I was 'afraid' that it was something with the perspective. Did not know
about the camera trick though. That was a great help. Thank You!

(if others have interest)
I ended up with these settings :

camera {
  location  <-1,18,-50>
  //right     x*image_width/image_height
  right 4/3*x
 up y
 angle 10 //
  look_at   <0,2,0>
}

regard krus


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From: ingo
Subject: Re: strange slant of objects in an ordinary scene
Date: 21 Aug 2002 08:40:40
Message: <Xns92719601633FAseed7@povray.org>
in news:web.3d6386dd9fcb6fdc2f4bd1e30@news.povray.org krus wrote:

> I was 'afraid' that it was something with the perspective. Did not know
> about the camera trick though.

There is another trick, shearing the camera (or the whole scene) with a 
matrix. For an example look for 
yourpovray35directory/scenes/camera/shear.pov

It has the advantage that you can keep a wider camera angle. An small 
angle as you use now makes the whole scene look flatter, you loose a sense 
of depth.

Ingo


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From: krus
Subject: Re: strange slant of objects in an ordinary scene
Date: 22 Aug 2002 08:25:04
Message: <web.3d64d6da9fcb6fdc2f4bd1e30@news.povray.org>
ingo wrote:
>in news:web.3d6386dd9fcb6fdc2f4bd1e30[at]news.povray.org krus wrote:
>
>> I was 'afraid' that it was something with the perspective. Did not know
>> about the camera trick though.
>
>There is another trick, shearing the camera (or the whole scene) with a
>matrix. For an example look for
>yourpovray35directory/scenes/camera/shear.pov
>
>It has the advantage that you can keep a wider camera angle. An small
>angle as you use now makes the whole scene look flatter, you loose a sense
>of depth.
>
>Ingo
>

Thank You! Ingo!
Yes i thought that the scene lost some dynamic with the camera change but i
believed that to be the 'cost' of getting the perspective moderation. I
will experiment with the shear method
Thank you!
regards krus


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From: Brendan Ryan
Subject: Re: strange slant of objects in an ordinary scene
Date: 22 Aug 2002 21:32:33
Message: <3D65903A.3060202@global2000.net>
I made a scene that showed the terrestrial planets and some moons.  I 
had Venus on one side and the Earth on the other side and they looked 
distorted so I used an orothographic camera because that type of camera 
has no persecptive.
The reason why we notice the strange slant in pictures is that we can 
look at all parts of the picture, but don't notice anything with what we 
see with our eyes because the distortion is assumed to be there and it 
seems natural because we can't examine the sides of our vision field 
very easily unless we turn then it would not be distorted anymore there.
Brendan


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From: Rune
Subject: Re: strange slant of objects in an ordinary scene
Date: 23 Aug 2002 04:08:57
Message: <3d65ed99@news.povray.org>
Brendan Ryan wrote:
> The reason why we notice the strange slant in pictures
> is that we can look at all parts of the picture, but
> don't notice anything with what we see with our eyes
> because the distortion is assumed to be there and it
> seems natural because we can't examine the sides of
> our vision field very easily unless we turn then it
> would not be distorted anymore there.

Nah. Our eyes don't use perspective projection. The back "walls" of our
eye balls are curved, not plain and flat. But even if they did use
perspective projection, our brain would surely account for it and
correct it, so that we didn't percieve things as distorted, even if we
could examine the edge our our field of vision.

Followup-to povray.off-topic...

Rune
--
3D images and anims, include files, tutorials and more:
rune|vision:  http://runevision.com (updated July 12)
POV-Ray Ring: http://webring.povray.co.uk


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