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From: gregjohn
Subject: The Orthographic Decapitation
Date: 12 Dec 2012 09:00:02
Message: <web.50c88d26cb32d3e47b8a80e0@news.povray.org>
Hi. I was starting to experiment with the use of povray to make a single-image
sprite sheet.  It would of course be useful to make it using an orthographic
camera.  But my figures are getting cut off.   Is there a way around this?
TIA.


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From: clipka
Subject: Re: The Orthographic Decapitation
Date: 12 Dec 2012 09:44:50
Message: <50c89862@news.povray.org>
Am 12.12.2012 14:56, schrieb gregjohn:
> Hi. I was starting to experiment with the use of povray to make a single-image
> sprite sheet.  It would of course be useful to make it using an orthographic
> camera.  But my figures are getting cut off.   Is there a way around this?
> TIA.

Move the camera further away, maybe?


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From: gregjohn
Subject: Re: The Orthographic Decapitation
Date: 12 Dec 2012 10:25:01
Message: <web.50c8a0d8b526f522ae3cb5160@news.povray.org>
clipka <ano### [at] anonymousorg> wrote:
> Am 12.12.2012 14:56, schrieb gregjohn:
> > Hi. I was starting to experiment with the use of povray to make a single-image
> > sprite sheet.  It would of course be useful to make it using an orthographic
> > camera.  But my figures are getting cut off.   Is there a way around this?
> > TIA.
>
> Move the camera further away, maybe?

hmm, no.  It still doesn't want objects in the bottom of the image, even with
the height doubled.


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From: Samuel Benge
Subject: Re: The Orthographic Decapitation
Date: 12 Dec 2012 12:00:01
Message: <web.50c8b6dbb526f522d09d0ca60@news.povray.org>
"gregjohn" <pte### [at] yahoocom> wrote:
> clipka <ano### [at] anonymousorg> wrote:
> > Am 12.12.2012 14:56, schrieb gregjohn:
> > > Hi. I was starting to experiment with the use of povray to make a single-image
> > > sprite sheet.  It would of course be useful to make it using an orthographic
> > > camera.  But my figures are getting cut off.   Is there a way around this?
> > > TIA.
> >
> > Move the camera further away, maybe?
>
> hmm, no.  It still doesn't want objects in the bottom of the image, even with
> the height doubled.

Did you actually move the camera away? Or did you just mess with its angle,
right/up vectors or scaling? Moving the camera away should be doing the trick,
unless your objects are still inhabiting the camera's location. You might want
to try something like this: location <0, .5, -1>*1000

Sam


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From: gregjohn
Subject: Re: The Orthographic Decapitation
Date: 12 Dec 2012 12:45:01
Message: <web.50c8c187b526f52247b8a80e0@news.povray.org>
"Samuel Benge" <stb### [at] hotmailcom> wrote:
> "gregjohn" <pte### [at] yahoocom> wrote:
> > clipka <ano### [at] anonymousorg> wrote:
> > > Am 12.12.2012 14:56, schrieb gregjohn:
> > > > Hi. I was starting to experiment with the use of povray to make a single-image
> > > > sprite sheet.  It would of course be useful to make it using an orthographic
> > > > camera.  But my figures are getting cut off.   Is there a way around this?
> > > > TIA.
> > >
> > > Move the camera further away, maybe?
> >
> > hmm, no.  It still doesn't want objects in the bottom of the image, even with
> > the height doubled.
>
> Did you actually move the camera away? Or did you just mess with its angle,
> right/up vectors or scaling? Moving the camera away should be doing the trick,
> unless your objects are still inhabiting the camera's location. You might want
> to try something like this: location <0, .5, -1>*1000
>
> Sam

No, I actually doubled it (but at the same time moved new figures closer to the
bottom.

Will post code at p.g.


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From: clipka
Subject: Re: The Orthographic Decapitation
Date: 12 Dec 2012 13:34:29
Message: <50c8ce35$1@news.povray.org>
Am 12.12.2012 18:40, schrieb gregjohn:

>> Did you actually move the camera away? Or did you just mess with its angle,
>> right/up vectors or scaling? Moving the camera away should be doing the trick,
>> unless your objects are still inhabiting the camera's location. You might want
>> to try something like this: location <0, .5, -1>*1000
>>
>> Sam
>
> No, I actually doubled it (but at the same time moved new figures closer to the
> bottom.

That was the mistake: At the same time as doubling the distance to the 
coordinate origin, you also doubled the viewport and scene dimensions. 
So while the camera now doesn't cut off the heads of the old population, 
you have moved new figures into the region where heads are being cut pff 
/now/.

/Only/ increase the camera's distance, leave the viewport size 
unchanged, and don't add new people.


The whole reason for this effect is that the camera must shoot its rays 
from /somewhere/ - infinity won't work, as it's not a good value to do 
math on ;-). So the rays are shot from the plane going through the 
camera position and being perpendicular to the camera direction. If one 
of your figures sticks its head through this plane, the camera rays will 
hit (and thus see) only his inside, effectively decapitating him.


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From: gregjohn
Subject: Re: The Orthographic Decapitation
Date: 15 Dec 2012 13:40:01
Message: <web.50ccc39bb526f5225474b7bd0@news.povray.org>
clipka <ano### [at] anonymousorg> wrote:>
> The whole reason for this effect is that the camera must shoot its rays
> from /somewhere/ - infinity won't work, as it's not a good value to do
> math on ;-). So the rays are shot from the plane going through the
> camera position and being perpendicular to the camera direction. If one
> of your figures sticks its head through this plane, the camera rays will
> hit (and thus see) only his inside, effectively decapitating him.

Thanks for the articulate explanation.  I still think the diagrams in the povray
camera docs drive me crazy: when I eventually figure out how to do some new
trick, it seems it was after I left a blind alley I was led to from my
presumptions about the picture of the angles, etc.

Anyway, this was an idea I saw at StackOverflow for sprites.  And this is the
one case where povray knocks all other apps flat for being able to make a bunch
of sprites at once.


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From: MichaelJF
Subject: Re: The Orthographic Decapitation
Date: 15 Dec 2012 14:55:01
Message: <web.50ccd4c2b526f5228c12479d0@news.povray.org>
clipka <ano### [at] anonymousorg> wrote:
> Am 12.12.2012 14:56, schrieb gregjohn:
> > Hi. I was starting to experiment with the use of povray to make a single-image
> > sprite sheet.  It would of course be useful to make it using an orthographic
> > camera.  But my figures are getting cut off.   Is there a way around this?
> > TIA.
>
> Move the camera further away, maybe?

Moving away an orthographic camera? What should be achieved from this?

Best regards,
michael


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From: MichaelJF
Subject: Re: The Orthographic Decapitation
Date: 15 Dec 2012 15:15:00
Message: <web.50ccda15b526f5228c12479d0@news.povray.org>
"gregjohn" <pte### [at] yahoocom> wrote:
> clipka <ano### [at] anonymousorg> wrote:>
> > The whole reason for this effect is that the camera must shoot its rays
> > from /somewhere/ - infinity won't work, as it's not a good value to do
> > math on ;-). So the rays are shot from the plane going through the
> > camera position and being perpendicular to the camera direction. If one
> > of your figures sticks its head through this plane, the camera rays will
> > hit (and thus see) only his inside, effectively decapitating him.
>
> Thanks for the articulate explanation.  I still think the diagrams in the povray
> camera docs drive me crazy: when I eventually figure out how to do some new
> trick, it seems it was after I left a blind alley I was led to from my
> presumptions about the picture of the angles, etc.
>
> Anyway, this was an idea I saw at StackOverflow for sprites.  And this is the
> one case where povray knocks all other apps flat for being able to make a bunch
> of sprites at once.

Moving away an orthographic camera usually yields nothing since the camera is
orthographic.
That is the nature of an orthographic camera.
You must fit your scene into the orthographic view.

Best regards,
michael


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From: clipka
Subject: Re: The Orthographic Decapitation
Date: 15 Dec 2012 15:32:29
Message: <50ccde5d@news.povray.org>
Am 15.12.2012 20:51, schrieb MichaelJF:
> clipka <ano### [at] anonymousorg> wrote:
>> Am 12.12.2012 14:56, schrieb gregjohn:
>>> Hi. I was starting to experiment with the use of povray to make a single-image
>>> sprite sheet.  It would of course be useful to make it using an orthographic
>>> camera.  But my figures are getting cut off.   Is there a way around this?
>>> TIA.
>>
>> Move the camera further away, maybe?
>
> Moving away an orthographic camera? What should be achieved from this?

Making the figures not getting cut off.

Even in an orthographic render, the camera position determines what you 
see: Everything "in front" of the camera is visible, everything "behind" 
is not.


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