This is a good question, since tangents have several meanings in the world of animation, and particularly in computer animation. Tangents typically refer to an aspect of a key frame, in that they define how the computer should ‘in-between’ the frames that are not specifically defined by keys (known as “key frames”). Since computer animators do not draw each frame, tangents help keep animation control of the frames in between these special key frames. If something needs to ‘ease in’ to a key (imaging the height of a bouncing ball at the top of it’s arc), then the tangent may be flat. If the motion does an abrupt ‘about face’ (such as the height of the same ball when it strikes the ground and is sent back upward), then the tangent might be much sharper.Tangents in this sense are absolutely critical... so I’m guessing that the question at hand doesn’t actually pertain to this sort of tangent.
What I think the question is referring to is something having to do with the arcs of motion. Arcs are a very important principle of animation, since many natural or organic movements are defined in terms of an arc. Very rarely do we move from point A to point B in a direct, straight line – it’s just not natural. Robots may move this way, but humans, or dogs, or blades of grass actually are much more likely to move in a fluid, arcing sort of way.
The term “tangents” in this area may be referring to an invisible line that something moving sort of ‘bumps’ into. Sometimes called “walls,” these imaginary boundaries can be seen in animation that may need with it’s arcs. I recall a shot I was working on in which a character swung his hands up over his head. Other animators pointed out that half way up the arc, the hand seemed to ‘bounce’ off a wall that wasn’t there. It turned out that my arc was actually move like a sideways “V” and once I noticed it, it was quite obvious, and quite distracting. Fixing it wasn’t exactly simple (sometimes the successive breaking of joints means that tracking down the source of the problem is tricky) but in the end I was able to clean up the arc, which improved the shot immensely.
Cleaning up arcs is a very important step of the final polish pass when animating, and it’s one of the things that can distinguish really really excellent animation from animation that is just ‘really good.’
Happy Animating!
Animation Mentor Staff
3 comments:
Wow, all true. What I usually take it to mean is when a shape is neither in front of or behind another shape, but just touching the edge. That creates a lot of visual attention. Good or bad is how and when you use it in your poses and staging.
Hi, I agree with Cmbancroft. 'To avoid tangents' is to avoid having lines in de visual graphic shape touching eachother as it both attracks the eye and makes the image flat. Making the shapes overlap eachother would communicate depth more clearly as we can see which shape is in front of the other. This also is a part of 'keeping a clear silhouette' of course.
But all rules are there to be broken. Take a look at 'Brendan and the Secret of Kells', which is an Irish animated feature just out now in Europe, where I did an internship on. They use a style in which they do create tangents in the poses to purposely make the image flat. This 2D film is utilising every aspect of its flat nature. It taps into the illumination from the Middle Ages that it's based on. Check it out:
http://www.thesecretofkells.com/
Some clips (in French):
http://twitchfilm.net/site/view/three-new-clips-for-tom-moores-brendan-and-the-secret-of-kells/
Good post. I find though, that avoiding tangents in animation is the same as avoiding them in an image. When the point/edge of a body part intersects with another body part or prop/environment, it causes a confusing silhouette.
An actual mathematical tangent is when a line runs alone the edge of a circle http://tinyurl.com/cbykux
When that happens in a drawing, it usually makes the drawing/pose look flat and confusing.
So in terms of avoiding in animation, it revolves around a pose of the character. If the character is doing a walk cycle, and the hand is brought up to the face to show exaggeration, if the hand edge touches the face edge, it looks like he's punching himself since there's not clear depth to show whether or not the hand is in the front or behind the face.
Hope this helps.
Phil
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