POV-Ray : Newsgroups : povray.general : Re: Camera perspective Server Time
16 Nov 2024 19:17:27 EST (-0500)
  Re: Camera perspective (Message 1 to 3 of 3)  
From: Rob Napier
Subject: Re: Camera perspective
Date: 28 Apr 1998 14:54:07
Message: <354625CF.380FD077@cisco.com>
Daren Scot Wilson wrote:
> 
> Alan Grainger wrote:
> >
> > Is it just me, or does the normal camera make everything look slightly out
> > of perspective.  With an angle of 20, it looks about right.  Am I missing
> > something?
> 
> Ya, it's just you. The rest of us live in a different fabric of
> spacetime where geometry is completely different...
> 
> No, seriously,   your computer monitor only takes up 10-20 degrees of
> your eye's field of view, 30 if you're sitting real close to a 17".  So
> it only makes sense that a camera angle of 20 or so used to render a
> full screen image looks natural.  Of course, we artists want to show off
> more of our scenes than that.
> 
> If you have a TV, observe closely the camera shots in sitcoms, talk
> show, ads, etc.   TV cameras rarely get much past about 30 deg. field of
> view.

Sorry to drag up such an old thread, but this is exactly the question I
came to povray.general for (wow! useful info in a newsgroup). I wanted
to 
make sure that I understood this answer, and that it relates to the
problem
I'm having.

When I render three spheres along the top of the viewable area, with no
explicit angle statement, all three are stretched out of shape towards
the
outside of the image (i.e. the left corner sphere stretches towards the
left corner). Here's the .pov (based on first.pov):

-- Start --#include "colors.inc"

camera {
   location <0,0.5,-7>
   look_at <0,0,0>
}

light_source { <22,16,-300> color White}

plane { <0,1,0>,-1
	   texture {
  pigment {color Silver}
  normal {bumps 0.5 scale .8}
  finish {phong 1 reflection .5 ambient 0.4 diffuse 0.2} } }

sphere { <0,0,0>,1
	    texture { 
  pigment { color Blue }
  finish { reflection 0.2 diffuse 0.1 ambient 0.8 phong .8 } } }

sphere { 0, 6
   texture { 
      pigment { color White }
      finish { reflection 0.2 diffuse 0.1 ambient 0.8 phong .8 }
   } 
   translate <22, 16, 50>
}

sphere { 0, 6
   texture { 
      pigment { color White }
      finish { reflection 0.2 diffuse 0.1 ambient 0.8 phong .8 }
   } 
   translate <-22, 16, 50>
}
sphere { 0, 6
   texture { 
      pigment { color White }
      finish { reflection 0.2 diffuse 0.1 ambient 0.8 phong .8 }
   } 
   translate <0, 16, 50>
}

-- End --

The first one is perfect (center of the view). The other three (near the
edges of the view) are stretched. I can get the distortion out by
setting
the angle around 30 (that sounds familiar...), but that means I have to
haul the camera back to about -75*z to see the whole scene. Is that just
a
fact of life, or is there a way to get rid of the distortion? Is there
something magical about 30 degrees that makes this a good angle to use
quote "all the time"?

On the same note, my original goal was to do the moon with a sky_sphere,
in a similar way to the example of the sun in the docs (though I use a
pigment map to get the seas, etc). When I rotate the sky_sphere to put
the
moon in the upper right, I get the same distortion. It looks like angle
cleans it up a bit, too.

Thanks,
Rob 

-- 
Rob Napier        | Vote "Linus Torvalds: Builder of the Century"
rna### [at] ciscocom |    http://www.employees.org/~rnapier/linus.html
+=========================================================================+
Wow, I'm being shot at from both sides.  That means I *must* be right. 
:-)
	    -- Larry Wall in <199### [at] wallorg>
+=========================================================================+


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From: Lance Birch
Subject: Re: Camera perspective
Date: 29 Apr 1998 04:16:24
Message: <6i6nlu$9fn$1@oz.aussie.org>
Can't you change the camera vectors or something?

--
Lance Birch
Remove the smiley to e-mail.
http://www1.tpgi.com.au/users/ambient/lance


Post a reply to this message

From: Rob Napier
Subject: Re: Camera perspective
Date: 30 Apr 1998 14:13:11
Message: <3548BF37.A9802A4C@cisco.com>
Lance Birch wrote:
> 
> Can't you change the camera vectors or something?

Setting angle is just a convient way of resetting the camera vectors,
so this doesn't change the issue.

Rob

-- 
Rob Napier        | Vote "Linus Torvalds: Builder of the Century"
rna### [at] ciscocom |    http://www.employees.org/~rnapier/linus.html
+=========================================================================+
Wow, I'm being shot at from both sides.  That means I *must* be right. 
:-)
	    -- Larry Wall in <199### [at] wallorg>
+=========================================================================+


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