Hi everyone

Here's my latest Lego render. I've used focal blur in this scene but I 
think I need to use motion blur. Is motion blur available in latest 
version of POV-Ray or do I have to use MegaPov (or another patched 
version or POV-Ray)?

Bye for now

Reuben

=====================================
Download 3D Lego models and other resources from:
http://www.pearse.co.uk/lego
=====================================

Post a reply to this message

Attachments:
Download 'superman.png' (380 KB)

Preview of image 'superman.png'

Reuben Pearse wrote:

> Here's my latest Lego render. I've used focal blur in this scene but I 
> think I need to use motion blur. Is motion blur available in latest 
> version of POV-Ray

no, but you can simulate it by rendering an animation moving the
object in "sub-exposure" steps and then averaging the frames. This
also gives you the artistic freedom to give more weight to the final
frame if you want a more comic-like asymmetric blur for this scene.

Post a reply to this message

On 04/11/2012 14:30, Christian Froeschlin wrote:
> Reuben Pearse wrote:
>
>> Here's my latest Lego render. I've used focal blur in this scene but I
>> think I need to use motion blur. Is motion blur available in latest
>> version of POV-Ray
>
> no, but you can simulate it by rendering an animation moving the
> object in "sub-exposure" steps and then averaging the frames. This
> also gives you the artistic freedom to give more weight to the final
> frame if you want a more comic-like asymmetric blur for this scene.

Thanks for the info. Can you point me to any websites or tutorials that 
explain this technique in more detail? Some example POV code would be 
useful.

Reuben

Post a reply to this message

Reuben Pearse wrote:

> Thanks for the info. Can you point me to any websites or tutorials that 
> explain this technique in more detail? Some example POV code would be 
> useful.

Mostly I just remembered the thread "motion blur test" in these groups:

http://news.povray.org/povray.binaries.animations/thread/%3Cweb.4cdc16a1920b620ecaa39c860%40news.povray.org%3E/?mtop=352976

Post a reply to this message

On 4-11-2012 15:30, Christian Froeschlin wrote:
> Reuben Pearse wrote:
>
>> Here's my latest Lego render. I've used focal blur in this scene but I
>> think I need to use motion blur. Is motion blur available in latest
>> version of POV-Ray
>
> no, but you can simulate it by rendering an animation moving the
> object in "sub-exposure" steps and then averaging the frames. This
> also gives you the artistic freedom to give more weight to the final
> frame if you want a more comic-like asymmetric blur for this scene.

Ah! A little trick I might need. The animation ng is not regularly open 
on my system, but I should give it a look once in a while :-)

Thomas

Post a reply to this message

Reuben Pearse <reu### [at] pearsecouk> wrote:
> On 04/11/2012 14:30, Christian Froeschlin wrote:
> > Reuben Pearse wrote:
> >
> >> Here's my latest Lego render.

cool!

> >> I've used focal blur in this scene but I
> >> think I need to use motion blur. Is motion blur available in latest
> >> version of POV-Ray
> >
> > no, but you can simulate it by rendering an animation moving the
> > object in "sub-exposure" steps and then averaging the frames. This
> > also gives you the artistic freedom to give more weight to the final
> > frame if you want a more comic-like asymmetric blur for this scene.
>
> Thanks for the info. Can you point me to any websites or tutorials that
> explain this technique in more detail? Some example POV code would be
> useful.

Here's the scene I use when averaging a number of pre-rendered frames:

#version 3.7;
global_settings{assumed_gamma 1.0}
#default{finish{ambient 1}}

camera{
 orthographic
 right x up y
 location -z
}

#declare n_frames = 80;
#declare image_name_ = "superman"
#macro image_type_() png #end

plane{z,0
 pigment{
  average
  pigment_map{
   #for(V, 1, n_frames)
    [1
     #declare image_name = concat(image_name_, str(V, -(log(n_frames)/log(10) +
1), 0))
     image_map{image_type_() image_name}
     translate -(x+y)/2
    ]
   #end
  }
 }
}


Memory requirements can become pretty high when using large numbers of images,
especially if they are in the HDR format (but they work really well, especially
when rendering star fields).

Sam

Post a reply to this message

Hm, I'm not quite sure, if this alone solves the issue of having motion blur
with POV 3.7. Should this wonderful superman not having decreasing transparency
during the flight? If you only average pictures of the flight, you will probably
get more blur than expected, since POV doesn't know the sequence of the
pictures. May be, proper weights in the average map will help. But you are still
limited to 256 entries. An other approach is to have copies of the blurred
object with decreasing transparency in the scene. But to find the correct
positions and transparencies is the hard job. Christian Froeschlin gave an
example with his entry "glocken" at the IRTC april 2006, which shows the idea
but the difficulties likewise (rendered at a higher resolution then the original
entry).

Best regards,
Michael

Post a reply to this message

> Ah! A little trick I might need. The animation ng is not regularly open
> on my system, but I should give it a look once in a while :-)
>
> Thomas

Ah! That is why I get no comment from you to my first (very technically) entry
there. And I value your comments very much ;-)

Best regards,
Michael

Post a reply to this message

> Hm, I'm not quite sure, if this alone solves the issue of having motion blur
> with POV 3.7. Should this wonderful superman not having decreasing transparency
> during the flight? If you only average pictures of the flight, you will probably
> get more blur than expected, since POV doesn't know the sequence of the
> pictures. May be, proper weights in the average map will help. But you are still
> limited to 256 entries. An other approach is to have copies of the blurred
> object with decreasing transparency in the scene. But to find the correct
> positions and transparencies is the hard job. Christian Froeschlin gave an
> example with his entry "glocken" at the IRTC april 2006, which shows the idea
> but the difficulties likewise (rendered at a higher resolution then the original
> entry).
>
> Best regards,
> Michael
>
>

For the comicks like decreased transparency.
In this sample scene, all frames have the same weight, but it can be 
changed:
    #for(V, 1, n_frames)
     [V // the weight goes from 1 to n_frames.
      #declare image_name = concat(image_name_, str(V, 
-(log(n_frames)/log(10) +
1), 0))
      image_map{image_type_() image_name}
      translate -(x+y)/2
     ]
    #end

By replacing the [1 by [V, the first image have a weight of 1, the 
second a weight of 2,...
You can also use V/n_frames if you want to keep the weight parameter no 
larger than 1.
You can increase the last image further in a few ways:
Add some number to the last image's weight.
Use pow(V,2) or pow(V/n_frames,2) for the weight. You can use a power of 
3, 4 or some intermediate value if you want.
This assume that each frame is created in the direction of the movement 
and that you want the last frame to dominate.

The limit of 256 entries is not a problem unless you have a very long 
motion blur trail. If you use decreasing transparency, it's even less of 
a problem, even with rather long trails.



Alain

Post a reply to this message

Alain <kua### [at] videotronca> wrote:

> > Hm, I'm not quite sure, if this alone solves the issue of having motion blur
> > with POV 3.7. Should this wonderful superman not having decreasing transparency
> > during the flight? If you only average pictures of the flight, you will probably
> > get more blur than expected, since POV doesn't know the sequence of the
> > pictures. May be, proper weights in the average map will help. But you are still
> > limited to 256 entries. An other approach is to have copies of the blurred
> > object with decreasing transparency in the scene. But to find the correct
> > positions and transparencies is the hard job. Christian Froeschlin gave an
> > example with his entry "glocken" at the IRTC april 2006, which shows the idea
> > but the difficulties likewise (rendered at a higher resolution then the original
> > entry).
> >
> > Best regards,
> > Michael
> >
> >
>
> For the comicks like decreased transparency.
> In this sample scene, all frames have the same weight, but it can be
> changed:
>     #for(V, 1, n_frames)
>      [V // the weight goes from 1 to n_frames.
>       #declare image_name = concat(image_name_, str(V,
> -(log(n_frames)/log(10) +
> 1), 0))
>       image_map{image_type_() image_name}
>       translate -(x+y)/2
>      ]
>     #end
>
> By replacing the [1 by [V, the first image have a weight of 1, the
> second a weight of 2,...
> You can also use V/n_frames if you want to keep the weight parameter no
> larger than 1.
> You can increase the last image further in a few ways:
> Add some number to the last image's weight.
> Use pow(V,2) or pow(V/n_frames,2) for the weight. You can use a power of
> 3, 4 or some intermediate value if you want.
> This assume that each frame is created in the direction of the movement
> and that you want the last frame to dominate.
>
> The limit of 256 entries is not a problem unless you have a very long
> motion blur trail. If you use decreasing transparency, it's even less of
> a problem, even with rather long trails.
>
>
>
> Alain

Yes, your proposal is much more detailed than mine. In fact I only mentioned the
general idea that simply averaging pictures of a flight will not yield a motion
blurred picture and proper weights are needed. But I think you have to play
around a lot with the weights and the number of images to find a proper image.

Best regards,
Michael

Post a reply to this message