Spline curves are a method to represent motion in Maya and they can be found and edited in the Graph Editor.

how do they work?

They represent changes in value over time.

as the curve travels to the right it means that is traveling during time and as the same curve decreases or increases means that is changing in value. However the up and down values do not indicate that that in the viewport the object is going up or down such as it happens for rotation values, but for translate y attributes there is a direct visual correlation to the viewport.

Splines and spacing

how changes in the spline curves affect the spacing of a motion?

the large it is the change in value the larger it would be the amount of movement and slight change in value lead to a small amount of movement and when the curve is horizontal the curve attribute would be still with no value changes.

Tangents types

tangents are handles around a key frame and are employed to adjust the curve’s angle and direction before and after the key. There can be found several Ganges types in maya and can be used as a starting point. Such as auto tangent function which adjust the key tangents automatically depending on their location: keys at the extremity are flat and transitional keys, where the curve is the same direction on both sides is smooth and as the keys are edited the tangents will automatically orient. When refining an animation though, is not used one type of tangents for all the keys but different type of tangents depending on the key. Spline tangents make a smooth transition between keys and don’t flatten out. Clamped tangents are similar to spline tangents but they will not overshoot on adjacent keys close in value. Linear tangents make a straight line from key to key and very sharp transition useful for when a ball hits the ground for instance. Flat tangents which make the tangent flat common to use at extremes keys and in transitional keys it will create a decrease in velocity. Stepped keys do not interpolate and will hold still until the next key frame creating a stair-like keys they are used for blocking in full animation. Plateau tangents don’t overshoot and flatten out extreme keys.

this is a chart of common uses for these tangents types:

Tangent handles

tangent handles help create any type of curve we want. There are two types of tangent handles: weighted and non-weighted (all the same length and have the same amount of influence on a curve). Usually the tangents handles are unified and move together, however if we use the break tangents button the handles become dashed moving independently. Weighted tangents have differed Ing length which depend on the distance in value between key frames.

advantages of handles:

• it helps shaping the curves

• scale the curve more accurately

• it can create sharp angles with fewer keys

Disadvantages of handles

• Have less control over larger spacing areas
• spacing can be affected by editing close keys

Reference book

Naas, P., n.d. How to cheat in Maya 2017.