Planet Rotation Smoothness

Hey all, fairly new at all this, but I’ve created some planets for some intros.
I’ve done some animations with them both from png/jpg/bmp image sequences and direct to avi or others. My question is, what should I do to ensure that the rotation is as smooth as possible?

I seen it go from ok to jumpy. My initial thought was to change the slope of my IPO to make full rotations, 365 deg, take longer (like in 500 or more frames) so that there are more frames in the movement. So essentially I would have a long sequence with fairly slow rotation, then speed it up if needed in my video editing software. Am I going about this the right way?

Not really IMO. Creating more frames only to remove them later (which is what will happen when you adjust the time in a video editor, assuming you’re using the same frame rate in all instances) seems both redundant and a possible source for glitches – how good is your video 'ware at re-sampling? Will it re-sample at a perfectly consistent rate? If not, you may get less-than-smooth results.

What seems the better way to go is to determine the exact length (i.e., time) you need for the rotation sequence, how much rotation is best in that time to get the smoothness you want, then render just the necessary number of frames (with perhaps a little head and tail padding) and no more.

Finding the right timing may take a few trial runs, but here’s a way I’ve used that cuts down on total Blender rendering time:

After making your best guess at the sequence time and rotation rate, rather than doing a full render, output a “playblast” using the “Render this window…” button that’s at the right side of every 3D Window menu bar. CTRL+RMB this button to do a quickly-rendered animation of the 3D window view – no lighting, no textures, just the movement, but that’s the important thing at this point. Use whatever your target frame rate will be. You can output to any convenient format just as with a full render.

Place this “playblast/pre-viz” in your video editor and try the timing. If it needs tweaking, you can adjust it in Blender and run out another quick-render. Once you get it as you want it, set up for full render and make the “beauty” version.

In the past I’ve used a video app (Virtual Dub) to output versions of a base sequence with different lengths by jiggling the frame rates on output, but I’ve found that the playblast approach is both faster and more accurate; you can get things perfect down to the exact frame before spending the time on a full render.

Ok, so I really do need the help. I just did a 300 frame series at something like 1200xsomething as png’s. They’re jumpy.

To answer your question, right now I’m using Sony Vegas. I import them as an image sequence. Its worked for lots of other images, but this is the first time I’ve tried it with an real animation.
I’ll try your suggestion, but should I be doing it as a still image sequence?
Or video? Or doing it with Blender’s sequence editor?

I’m using Sony Vegas, so I’m not sure how good it is at fast/slow motion.

So should I be using an image sequence or trying different video formats?

Sorry if this a double post, something wacky going on with the forums.

Not sure why my previous replies are not showing up…

Anyway, should I be using frames like png’s or trying different video formats? I will say that I have had some smooth outputs in video, but not had one yet from an image sequence. Why would this be?

I just tried the Cinepak and it is so far the smoothest, however, 250 frames are only 14mb and it looks like its lower resolution or highly compressed, not bad, but I’m pretty good at spotting improply compressed images, so it bugs me.

How are you viewing the image sequence? The player utility you use may be having some probs with an image sequence depending on (among other things) the size of your renders – large images demand more system resources. Keep in mind that an image sequence viewed in a player/viewer is basically the same as uncompressed video, and may represent many hundreds of Mb of data for the player/viewer to chew on.

Video formats are probably playing back more smoothly because you have some kind of compression activated. Try outputting the same “smooth” sequences to raw (uncompressed) AVI – one of the output options in Blender – and see if your player “chokes” on it.

I never knew about the playblasts (in fact I’d never noticed the render this button).
Thanks for the great tip - that’ll save me loads of time.

I’ve been doing large png’s. I’m sure that has something to do with it.

Is there some better format I should be using? I really don’t care too much about size, just quality and clean playback.

Y’welcome. Blender karma actually – I was unaware of it also until not but a few months ago (been a user over 2 years), when I got the same tip on this forum. Just passin’ it on :D.

@ mapman – for image sequences I can’t say that any one image format is better than another, as long as it’s not lossy like JPEG. I’ve used mainly BMP (but that results in large files) and TGA (which can be compressed, lossless, and is much more compact).

In my experience most playback/viewer utilities (you didn’t identify yours, btw) tend to get balky trying to play an image sequence of large pixel dimensions. In doing some large-scale sequences for a client I made all my pre-vis and approval videos at 1/2-scale so they would be sure to play back well even if uncompressed, then rendered the finals at 100% scale but used a compression scheme in the final output to make the playback reliable at that size. Generally the upper end for uncompressed playback is around [1024 width] X [whatever depth your aspect ratio requires]. Anything over that and every player/viewer utility I’ve used gets uneven in its performance, but of course your experience may vary.

Alt A in the 3d window will also animate in the same way, but does not make a file.

I’m using Sony Vegas. It has an image sequence import that seems to work pretty well. Its gets a little goofy on playback but the final render is always good. When I’ve had trouble with jumpy rotations, its carried all the way through to a test dvd. That is why I thought that maybe each rotation frame was a little too fast, so I started trying to slow it down and increase the animation length. How about messing with the fps?