Motion blur, smears, and multiples

Have you come up with a good Moho trick? Need help solving an animation problem? Come on in.

Moderators: Víctor Paredes, Belgarath, slowtiger

Post Reply
User avatar
slowtiger
Posts: 6176
Joined: Thu Feb 16, 2006 6:53 pm
Location: Berlin, Germany
Contact:

Motion blur, smears, and multiples

Post by slowtiger »

This is gong to be a more general post not about the technique, but the aesthetics of these three devices.

Motion blur comes from life action photography/film and occurs when an object moves too fast for the fastest shutter speed to give a sharp impression. You all know how it looks like, here's a good example:
Image
Faster moving elements leave longer trails than slower ones. Bright elements are better visible than dark ones, and you need a good brightness contrast between moving elements and still backgrounds (or vice versa). Trails are curved in the path of motion: the hedge in the back has straight blur, the feet have curved blur.

CGI animation (like by Pixar) naturally uses this device to imitate a real-life-like look. In general they use motion blur in the same circumstances, scenes and camera angles as if it would appear in life action. It doesn't define a movement, it only refines a certain look and adds a little bit of extra "smoothness" to the animation. If it were left out, the animation might look a little bit jerkier, or give that odd effect of recent digital video in bright light (like sports documentation) where they use an extremely short shutter speed so each frame of video is of pristine sharpness. The effect is very much like the one of stroboscopic films.

2D drawn animation used something similar, the smear, not to enhance visual realism, but to indicate very fast exaggerated movement. This is not an artifact created by the shutter, but a graphic symbol with its own rules of application.
Image
Image
As you can see, the swishes (done with drybrush) indicate arcs of movement within a single frame - no software could figure this out by itself. Often the smear is combined with a multiple. A multiple (also called ghost image) is a frame containing several frames of motion in one - like this:
Image
The rules can be written like this:
  • - All swishes follow the path of motion.
    - Very fast movement is done in a continuous swish.
    - Movement over a longer screen distance can have multiples, their spacing is the same as it would be in normal, slower motion.
    - Multiples often only show the outline of one side, not both. An approaching element has the front outline visible, a departing element has the back outline visible.
    - Showing both outlines is recommended for vibrating or back-and-forth motions.
    - Multiples omit most details and concentrate on the visible ones with the best contrast.
    - Lines parallel to motion path are drawn, others more likely left out.
    - Usually the swish is done in only 1 frame, for a very fast movement. There can be a "swish trail echo" for some frames afterwards, but not more than 5 or so.
    - Repeating movement, like running legs or spinning wheels, use the same 3 or 5 shwishes repeatedly. Any multiples will have to be spaced differently in all frames, they must not follow an A-B-A pattern because then they would appear blinking. Also don't use the same number of multiples in each frame.
    - Having one smear between extremes gives a very snappy impression, like a hit. Inbetweens for a slow in/out have to maintain the spacing of the multiples within the smear.
As you can see it's impossible to implement these rules into any motion blur software. Besides, I think motion blur on drawn characters looks like crap.

Pure multiples (without smear) are also used to show impossibly fast movements in a very short time, or even several movements at once. I couldn't find any good examples yet, but there are many: at Disney (Alice in Wonderland: the carpenter, Donald in several shorts) and Tex Avery.

(Very entertaining screen grab collections can be found here: http://animationsmears.tumblr.com/ and here: http://tralfaz.blogspot.com/)

I did just a little test for myself with this GIF I found (the Shadoks, by Jacques Rouxel):
Image
I wondered if the animation could be enhanced without losing that snappy quality, so I added inbetweens, squashes, and a multiple:
Image
AS 9.5 MacPro Quadcore 3GHz 16GB OS 10.6.8 Quicktime 7.6.6
AS 11 MacPro 12core 3GHz 32GB OS 10.11 Quicktime 10.7.3
Moho 13.5 iMac Quadcore 2,9GHz 16GB OS 10.15

Moho 14.1 Mac Mini Plus OS 13.5
User avatar
KenW
Posts: 129
Joined: Tue Jul 17, 2007 8:08 pm
Location: Virginia, USA
Contact:

Re: Motion blur, smears, and multiples

Post by KenW »

Thanks Slowtiger,

Very good read here, and gives one a lot to contemplate when thinking of using this effect. :shock:
Danimal
Posts: 1584
Joined: Thu Nov 15, 2007 3:06 pm
Location: The Danimal Kingdom
Contact:

Re: Motion blur, smears, and multiples

Post by Danimal »

Simply OUTSTANDING post, slowtiger! Thank you!
~Danimal
User avatar
heyvern
Posts: 7035
Joined: Fri Sep 02, 2005 4:49 am

Re: Motion blur, smears, and multiples

Post by heyvern »

Awesome description.
I use to use that single motion frame trick with animated gifs a long time ago. You could make a 3 frame gif look like 20 frames by just inserting a single motion blurred frame and moving it slightly. Very effective.

----

In the ongoing discussion of "real" motion blur versus "cartoon" motion blur, a new "multipass" feature in Anime Studio could potentially be used to create the "smear" and "multiples" described pretty effectively.

For example, if you could have "motion curves" within the sub frames, multiple key frames of movement "between" two frames, the resulting motion blur could simulate a smear or multiples. By setting the amount of passes to a low amount so that you can "see" the steps, that single frame would look very much like the cartoon examples of a smear following the line of action. If sub key frames were available you could also SCALE elements within the blur to create the small to large "smear". This could potentially be done using bezier interpolation of a multipass feature rather than actually having keys to move around.

Just a thought.
User avatar
J. Baker
Posts: 1063
Joined: Wed Mar 23, 2005 7:22 pm
Location: USA
Contact:

Re: Motion blur, smears, and multiples

Post by J. Baker »

Just in case anyone didn't see the old motion blur topic, here's a tool (MoBlur for Windows & Mac) to create that effect...
http://www.flashpulse.com/animestudio/moblur.zip

Example created using Anime Studio and MoBlur...
Image
Post Reply