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Slow-motion ... .. .

Posted: Tue Dec 13, 2005 11:23 am
by hotfur
Hi all,

I've been fiddling with the physics-simulation thingies in blender. For a
while now, I've been looking for a button that tells blender at what speed
the animation should _physically_ run. Suppose I want to take a slow-mo
anim of a falling waterdrop, how do I do it ? (I know it can be done with
fiddling with the physical properties of the water and such, but that's a bit
of overkill)
One could say, slow down the framerate of the movie, but then you get
jerky motion.

Basically, I'm looking for a field that says: render for xxx frames per second animation.

Regards and thanks in advance,

Posted: Tue Dec 13, 2005 4:20 pm
by UglyMike
Just a guess....
You can specify your desired framerate in Blender, so specify 240 frames per second. (Render them out as individual frames). If you press "Play", your drop will fall in a single second of animation at 240fps (provided your disk/memory can keep up...)
Now, in an external program, create an animation based on the created frames but at 24 fps.
Instant slowdown by factor 10

Posted: Tue Dec 13, 2005 5:12 pm
by hotfur
Hi Mike,

My guess was that you would have the same renders, but with a
playback speeded up. If you down the framerate, you'd end up with the
same animation. Apparently I overlooked the obvious.


Posted: Tue Dec 13, 2005 5:22 pm
by joeri
I don't see how UglyMikes suggestion will get a slowmo. I think it gets a fast-mo. turning 240 into 24 frames is a speedup of 10x.
Turning 24 frames into 240 frames (a 10x slowmo) is another thing.
As hotfur states displaying 1 images for 10 frames will give jerky animation so,... It might be good for the physics to get a fps button, separated from the fps button that's already in blender and tells how many frames go into a second for the timeslider and avi-s. The physics need a fps or rather a sps: how many physic seconds go into a render second. Normaly 1:1 but at a 2x slowdown 1:2 (1 ph-seconds in 2 playback seconds). Or 10x speedup 10:1 ( 10 ph-seconds in 1 playback second).

Or,... Maybe physics could use the time-ipo, like all other objects do.

Posted: Tue Dec 13, 2005 7:14 pm
by Mats78
If you render a 1 second animation at 240 fps, it should mean that you get 240 images shown within a 1 sec timespan. Now, if you play that at 24 fps, you get a 10 sec animation. So, thus, a slowdown and slowmotion.

That said, UglyMikes suggestion should work ok.


Posted: Tue Dec 13, 2005 11:18 pm
by joeri
Sure. But blender does not render seconds it renders frames.

Unless the physics take the fps button into account rendering 240 frames will give you water that moves best like in a 9 second animation.

fps in blender goes as high as 120
and the fluid time buttons are... weird! (0.0) - (0.3) ???

Posted: Thu Dec 15, 2005 5:58 am
by Mats78
OK, sorry for stating the obvious =)

I haven't actually tried the fluid sim, but doesn't it take the amount of rendered frames into account? If you use the start time button to define the actual start time of the simulation (in seconds) for the first blender frame, and the end time to define the end time for the last frame. This way it should be possible to span a one second fluid simulation over 100 frames for example (start time: 0, end time: 1, blender animation from 1-100).


Posted: Thu Dec 15, 2005 5:34 pm
by joeri
I think somebody should take a look at it before it's added in the release.
It does not make sense to me to redefine start-endframes (have another set of start/end frame settings), unless it's some sort of mapping.

Posted: Fri Dec 30, 2005 10:08 am
by effstops
Actually, the best way to do this is to go in your anim/playback buttons (one of the scene sub-menus) and do a change your "Map New" setting.

If map old is set to 100 and map new is set to 400 then your entire animation will now be 4 times slower.