Hi,
I have animation that should last A seconds and have 25 fps.
Now I got a notice from customer that animation must be outputed in field 
render.

Should I only add to .ini
  field_render = on
or should I i.e. multipy by *2 final_clock and/or frame ?

What about subset start/end frame ?

Will resulting sert of images have 2 times more files?

-- 
#macro g(U,V)(.4*abs(sin(9*sqrt(pow(x-U,2)+pow(y-V,2))))*pow(1-min(1,(sqrt(
pow(x-U,2)+pow(y-V,2))*.3)),2)+.9)#end#macro p(c)#if(c>1)#local l=mod(c,100
);g(2*div(l,10)-8,2*mod(l,10)-8)*p(div(c,100))#else 1#end#end light_source{
y 2}sphere{z*20 9pigment{function{p(26252423)*p(36455644)*p(66656463)}}}//M

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In article <Xns### [at] 204213191226>, "Rafal 'Raf256' Maj"
<spa### [at] raf256com> wrote:

> I have animation that should last A seconds and have 25 fps.
> Now I got a notice from customer that animation must be outputed in field
> render.
>
> Should I only add to .ini
>   field_render = on
> or should I i.e. multipy by *2 final_clock and/or frame ?
>
> What about subset start/end frame ?
>
> Will resulting sert of images have 2 times more files?

Is it that difficult to try with some trivial scene? ;-)

No, of course it will not have twice as many frames.  There will be as many
output images as you specified.  Thus, if you want to create a one second
animation with 25 full frames, you want 50 images of 50 half frames.
Consequently, you ask POV-Ray to render 50 images and turn the field render
option on.  If you don't mess with anyhing else, you get what you need.

    Thorsten

____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

Visit POV-Ray on the web: http://mac.povray.org

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"Rafal 'Raf256' Maj" <spa### [at] raf256com> wrote in message
news:Xns### [at] 204213191226...
>
> I have animation that should last A seconds and have 25 fps.
> Now I got a notice from customer that animation must be outputed in field
> render.
>
> Should I only add to .ini
>   field_render = on
> or should I i.e. multipy by *2 final_clock and/or frame ?
>
> What about subset start/end frame ?
>
> Will resulting set of images have 2 times more files?

Noticed no one seems to be replying yet, you might want to also ask this in
the povray.animations group just so any discussion of it could benefit
others too.

This is one of those features I hardly looked at before, and that was
probably eight years ago when I did. Not to actually use it for television,
only to see how it worked. Going back to the Scene Help and checking on it
with actual animation rendering I'd say it needs no extra frames from a
normal animation. I believe the documentation tries to explain that "twice"
the frame rate would only be useful if you could get away with slower
motions of your animated objects or have a end result with higher frame
rate. Consider, for example, a bouncing ball with a speed looking physically
correct if animated without field rendering and another one which looks sped
up with field rendering on plus double the frames but kept to the same
timing, both with the same settings besides. Wouldn't look right.

Short answer: I can only assume there's no frame rate difference between TV
and non-TV rendering. Only that it would need to match television frame
rate. Someone with actual experience would need to give you a real answer.
Other than that, I think the idea of doubling frame number for field
rendering is something which might require a FPS increase which TV wouldn't
allow for. My belief is the interlaced frames are meant to be shown
alternatingly and thus at the same rate as a non-TV animation.

Sure hope you find the actual solution and then we'll both know.  :-)

Bob H.

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"Thorsten Froehlich" <tho### [at] trfde> wrote in message
news:3f583ffe@news.povray.org...
>
> No, of course it will not have twice as many frames.  There will be as
many
> output images as you specified.  Thus, if you want to create a one second
> animation with 25 full frames, you want 50 images of 50 half frames.
> Consequently, you ask POV-Ray to render 50 images and turn the field
render
> option on.  If you don't mess with anyhing else, you get what you need.

Alas... if I had waited a mere few minutes I might have noticed your answer
before I replied to him as well.

This doubling of frames is what I wasn't understanding from the
documentation. In rendering a little test and viewing non-interlaced, i.e.
regular mpeg, I came to the conclusion there wouldn't need to be twice as
many frames to look just like animation without field rendering. Or rather
that television might interlace in a frame by frame stepping which doesn't
actually merge the pairs into a single frame again. That is, except by
persistence of vision effect.

To clarify further, I guess I need to understand that the even/odd frames
are combined during television conversion, and so need a double rate to
equal uncombined frames? Only wondering out of curiosity in my case, not out
of necessity like Rafal.  :-)  I just didn't think the process merged
frames. Seems impossible to locate information about this being
demonstrated.

Bob H.

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You need to merge the frames, using some other software, into an interlaced
video of 25 fps. This is what I consider field-rendering. The result should
be interlaced video. POV-Ray doesn't merge them, but outputs 50 separate
files for 1 second of video. Their resolution is half the usual height.

VirtualDub may be able to do merge the files, with the right filters. Unless
you have something else ready at hand.

Regards,
Hugo

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I've done field rendering work in the past for NTSC TV output, but not with 
Povray.

Everyone thinks NSTC TV has 30 full frames per second, but it actually has 
60 half frames per second containing odd and even lines that are 
interlaced.  So YES, you will need to render twice as many frames, but they 
will be half frames, NO they are not combined into a single frame 
afterwards, they are output INTERLACED, first the odd frame, then the even 
one, and so on at 60 (half)FPS.  And get this: each interlaced half frame 
is actually different in time than the previous interlaced half frame.  
NTSC TV actually records movement at 60 (half)FPS, most people do not know 
that.

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Thanks for the explanation. Rafal probably has PAL at 50 FPS instead of the
60 for NTSC. And if PAL begins with odd lines too the +uo switch will be
needed since POV-Ray starts out with even lines. Although, perhaps it
already is conforming to PAL as is?

"None" <Non### [at] onca> wrote in message
news:Xns### [at] 204213191226...
> I've done field rendering work in the past for NTSC TV output, but not
with
> Povray.
>
> Everyone thinks NSTC TV has 30 full frames per second, but it actually has
> 60 half frames per second containing odd and even lines that are
> interlaced.  So YES, you will need to render twice as many frames, but
they
> will be half frames, NO they are not combined into a single frame
> afterwards, they are output INTERLACED, first the odd frame, then the even
> one, and so on at 60 (half)FPS.  And get this: each interlaced half frame
> is actually different in time than the previous interlaced half frame.
> NTSC TV actually records movement at 60 (half)FPS, most people do not know
> that.

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"Hugo Asm" <hua### [at] post3teledk> wrote in
news:3f587289$1@news.povray.org 

> You need to merge the frames, using some other software, into an
> interlaced video of 25 fps. This is what I consider field-rendering.
> The result should be interlaced video. POV-Ray doesn't merge them,
> but outputs 50 separate files for 1 second of video. Their
> resolution is half the usual height. 

Goal is to prepare movie for TV (i.e. PAL standard).
First I used 720x576 with 25 fpp, so one second of animation was:

start_frame=0  end_frame=25
start_clock=0  end_clock=1

in pov file
#declare Clock = clock; // Clock must be in seconds


Then when I realized that field render is needed i used same .ini file, I 
just added filed_render=yes
  start_frame=0  end_frame=25
  start_clock=0  end_clock=1
  filed_render=yes
and in .pov no hange 

and You are saing that in fact I need
  start_frame=0  end_frame=50
  start_clock=0  end_clock=1
  filed_render=yes
and in .pov   #declare Clock = clock;

?

In other words when creating field render material I must double tha 
frame rate ?

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In article <Xns### [at] 204213191226>, Raf256 
<spa### [at] raf256com> wrote:

> and You are saing that in fact I need
>   start_frame=0  end_frame=50
>   start_clock=0  end_clock=1
>   filed_render=yes
> and in .pov   #declare Clock = clock;
>
> ?
>
> In other words when creating field render material I must double tha
> frame rate ?

Yes, that is exactly what I said.

    Thorsten

____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

Visit POV-Ray on the web: http://mac.povray.org

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