A 1280X720 animation, 600 frames, of the camera flying through some space
debris. It has motion-blur but no antialiasing. (I thought I could get away
without AA due to the erratic and blurred camera motions, which will usually
hide the lack of AA--but the moon still shows some jaggies every now and then.)

I rendered 6000 original frames, then (also in POV-Ray) averaged-together
batches of 20 to get each final frame. The resulting motion-blur is 'full
blur'--meaning, it's as if the movie camera had a 360-degree shutter (i.e.,
always open.) No real film camera does that, though.  So I'll also post a
version that corresponds to a 'standard' 180-degree shutter. It might be
interesting to compare the subtle 'subjective experience' between the two.

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Attachments:
Download 'meteor_animation.avi.dat' (3991 KB)

Here's the 2nd version. Only 10 of the 20 original frames are blurred together
here--which creates 'missing gaps' of action, to mimic what a 'standard' film
movie camera would produce with its typical 180-degree shutter.

BTW, both versions are at 24fps.

Also, forgot to mention: The videos are old-style AVI files, compressed using
the XVID codec. (I *think* it's an identical but open-source implementation of
the standard Divx codec, as used on DVDs.)

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Attachments:
Download 'meteors_half_blur.avi.dat' (3931 KB)

Am 16.01.2013 11:27, schrieb Kenneth:
> A 1280X720 animation, 600 frames, of the camera flying through some space
> debris. It has motion-blur but no antialiasing. (I thought I could get away
> without AA due to the erratic and blurred camera motions, which will usually
> hide the lack of AA--but the moon still shows some jaggies every now and then.)
>
> I rendered 6000 original frames, then (also in POV-Ray) averaged-together
> batches of 20 to get each final frame. The resulting motion-blur is 'full
> blur'--meaning, it's as if the movie camera had a 360-degree shutter (i.e.,
> always open.) No real film camera does that, though.  So I'll also post a
> version that corresponds to a 'standard' 180-degree shutter. It might be
> interesting to compare the subtle 'subjective experience' between the two.

Thumbs up for the 360 degrees. I guess it's simply closer to the visual 
experience of real life.

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Looks great, although I'm not completely sold on the colour scheme :)

Motion blur is (yet) another trick on my to-play-with list...

Bill

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"Bill Pragnell" <bil### [at] hotmailcom> wrote:
>
> Motion blur is (yet) another trick on my to-play-with list...
>
> Bill

My simple averaging method is the 'poor man's way'--it doesn't at all reproduce
the 'photographic film' look of, say, a very bright light smeared across the
frame. In such a case, the smear would be equally bright from beginning to end.
In my case, the darker background of previous/later frames is averaged with each
frame's bright 'static' light pool. The result is a 'different', not
quite-so-bright smear. But it still looks pretty cool.

I think MegaPOV (?) has a built-in motion-blur method (no simple averaging of
frames) that produces a more accurate result.

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clipka <ano### [at] anonymousorg> wrote:

>
> Thumbs up for the 360 degrees. I guess it's simply closer to the visual
> experience of real life.

Interesting. I'm sort of 'stuck on the fence' between the two versions. On the
one hand, I do like the 'liquid-like' blur of the 360-deg version. On the other,
I'm so used to seeing/thinking about/dissecting 'film-like' motion blur that
it's the norm for me. (But I wonder if I'm just *telling myself* that it's
better??)

On my older CRT monitor (with a refresh rate of 85Hz), the 360-deg version takes
on a little bit of the 'look' of live video, rather than film. The 180-degree
version seems to reduce that effect, to my eyes (eyes/brain?)--which I find
rather fascinating in itself.

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Am 17.01.2013 08:03, schrieb Kenneth:
> "Bill Pragnell" <bil### [at] hotmailcom> wrote:
>>
>> Motion blur is (yet) another trick on my to-play-with list...
>>
>> Bill
>
> My simple averaging method is the 'poor man's way'--it doesn't at all reproduce
> the 'photographic film' look of, say, a very bright light smeared across the
> frame. In such a case, the smear would be equally bright from beginning to end.
> In my case, the darker background of previous/later frames is averaged with each
> frame's bright 'static' light pool. The result is a 'different', not
> quite-so-bright smear. But it still looks pretty cool.

If you'd use OpenEXR for the interim output, you could also get that 
bright light smear right.

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clipka <ano### [at] anonymousorg> wrote:

>
> If you'd use OpenEXR for the interim output, you could also get that
> bright light smear right.

Really??! Then I need to do some research; the whole HDRI thing is kind of a
mystery to me, re: its use *in* computer graphics.

Thanks.

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Am 17.01.2013 12:14, schrieb Kenneth:

>> If you'd use OpenEXR for the interim output, you could also get that
>> bright light smear right.
>
> Really??! Then I need to do some research; the whole HDRI thing is kind of a
> mystery to me, re: its use *in* computer graphics.

It's really pretty simple, as far as POV-Ray is concerned: While classic 
image formats essentially use integer values to represent colors, 
capping them at 100%, HDRI formats such as OpenEXR use floating-point 
values instead, enabling them to represent color values as high as e.g. 
6,550,400% (in the case of OpenEXR).

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clipka <ano### [at] anonymousorg> wrote:
> Am 17.01.2013 12:14, schrieb Kenneth:
>
> >> If you'd use OpenEXR for the interim output, you could also get that
> >> bright light smear right.
> >
> > Really??! Then I need to do some research; the whole HDRI thing is kind of a
> > mystery to me, re: its use *in* computer graphics.
>
>
> It's really pretty simple, as far as POV-Ray is concerned:

See, that shows how much I *don't* know ;-)

I've been reading up on OpenEXR today--fascinating stuff (including the
odd/different gamma computations that it uses internally, to ultimately display
the image on typical 8-bit monitors. At least as a Photoshop plug-in. The
*display* of HDRI images is one of the things that I've never clearly
understood.) As a serendipitous side-effect, it has also launched me on a quest
to get a much better understanding of alpha compositing--specifically the
differences between using pre-multiplied alpha and non-pre-multiplied in an
image element.

For my animation here, I initially came up with a scheme to render the various
elements separately--meteors, moon and background--using POV-Ray's
Image_Alpha=on for the meteors and moon. Basically to see if I could save time
in the rendering process, as well as adding AA solely to the moon (6000 frames
for the meteors, but only 600 for the moon and background elements, as they
didn't need blurring, IMO.) I ran into some trouble though (in 3.62) when
averaging-together just the meteor elements as a pre-step (again using
Image_Alpha): The resulting meteor blur, when finally overlaid onto the other
elements, showed dark fringes. I now realize that alpha-multiplication (or non-)
is one of the culprits (as well as 3.7 having corrected some errors in how alpha
image_maps are applied.)

Knowledge is good! ;-)

So my animation here is from 6000 re-rendered 'normal' frames, no compositing.

But this scene might be the first (animation) experiment I re-render in 3.7RC6,
as separate elements again--this time using HDRI, assumed_gamma 1.0, and one or
the other of the alpha-multiplication schemes.

Thanks again for the OpenEXR suggestion.

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