… for Visual Effects

Tip #656: Keyframe Interpolation Tips

Larry Jordan – LarryJordan.com

Interpolation is the process of estimating unknown values that fall between known values.

Interpolation is the process of estimating unknown values that fall between known values. The key phrase is: “between two known values.” (By comparison, extrapolation attempts to figure out where a line is going outside of a set of known points.)

Interpolation is at the heart of keyframe animation. We set a starting point and an ending point, then the software calculates all the points in the middle. What the interpolation settings determine is how those points are calculated.

Because interpolation generates the property values between keyframes, interpolation is sometimes called tweening. Interpolation between keyframes can be used to animate movement, effects, audio levels, image adjustments, transparency, color changes, and many other visual and audio elements.

Temporal interpolation is the interpolation of values in time; spatial interpolation is the interpolation of values in space. Some properties—such as Opacity—have only a temporal component. Other properties—such as Position—also have spatial components.

• Constant: When applied to a keyframe or curve segment, this method holds the keyframe at its current value and then abruptly changes to the new value at the next keyframe.
• Linear: When applied to a keyframe, this method creates a uniform distribution of values through the keyframe from its two adjacent keyframes. When applied to a segment, this method creates uniform distribution of values between points.
• Bezier: This method lets you manipulate the keyframe curve manually by dragging the tangent handles. If multiple Bezier keyframes are selected, or Bezier interpolation is applied to the curve segment, the handles of all selected keyframes are modified.
• Continuous: This method behaves like Bezier interpolation, but without access to the tangent handles (which are calculated automatically).
• Exponential: This method creates an exponential curve between the current keyframe and the next, changing the value slowly at first, then reaching its maximum rate of acceleration as it approaches the next keyframe.
• Logarithmic: This method creates a logarithmic curve between the current keyframe and the next, changing the value rapidly at first, then slowing drastically as it approaches the next keyframe.

EXTRA CREDIT

Here’s an Apple Support article to learn more.

… for Visual Effects

Tip #633: Storyboarding Visual Effects

Larry Jordan – LarryJordan.com

Storyboards and production design are integral to all visual effects.

This tip, written by visual effects artist, Miguel Cima, first appeared in StoryboardThat.com. This is a summary.

From the very beginning of the creative process, imagination is in play. Before a thing exists, it must be visualized in the mind. This happens in filmmaking all along the way. First the screenplay must be written, a necessary text exercise which does not allow for initial images. Then comes the storyboard. At this point, the first spark of what lies inside the artist’s mind comes to life.

Deep into film’s history, various techniques have been employed to insert imagery which was not filmed on set with things which were. Regardless of how special visual effects are accomplished, one central challenge has always been consistently presented to filmmakers: how can a scene be filmed when much of it cannot be seen at all? Here are some of the more common visual effects used in live action feature films, and how the filmmaker can approach mastering the art of “see you later.”

• Animation. The good news for the filmmakers is that a well-crafted storyboard will serve as a guide in pre-production to get cast and crew familiar with the idea of what the final frames and sequences will look like. When combined with character illustrations and production design renderings, a full picture can be grasped to help translate not only the action, but the mood of what will be added in later.
• Miniatures. One of the oldest tricks in the special visual effects book is the use of miniatures. Traditionally, this meant building scale models of environments to represent very large sets like entire cities, massive vehicles, huge structures, and so forth.
• Matte Paintings. Another time-honored method to add large-scale environments is the Matte Painting. There’s a few different ways to do it, but essentially, an artist paints a highly detailed photo-realistic set piece, often on a massive scale, to depict what a set could not.
• Stop Motion. There’s a certain charm to stop motion animation, even if the final product cannot mask what it is. From old classics like King Kong to 2015’s Oscar-Nominated Anomalisa, there’s a texture to exposing fully posable models one frame at a time that CGI can never recreate.
• Doubling. Everybody seems to love twins. And clones. Whatever the case, every time you see a double of a character on screen, it is almost invariably the technique of doubling which you are watching (as opposed to using real-life twins, triplets, etc.). But as always, doing early tests with the tech on hand can do an even better job on performance prep.

EXTRA CREDIT

The article itself, as well as the illustrations, are a fun, easy read.

… for Visual Effects

Tip #615: Node vs Layer Compositing

Larry Jordan – LarryJordan.com

Nodes scale better, while layers are faster.

There are two radically different digital compositing workflows: node-based compositing and layer-based compositing.

Node-based compositing represents an entire composite as a procedural map, intuitively laying out the progression from source input to final output. (This is, in fact, the way all compositing applications internally handle composites.)

Node-based compositing interface allows great flexibility, including the ability to modify the parameters of an earlier image processing step “in context” (while viewing the final composite). Node-based compositing packages often handle keyframing and time effects poorly, as their workflow does not stem directly from a timeline, as do layer-based compositing packages. Software which incorporates a node based interface include Natron, Blender, Blackmagic Fusion, and The Foundry’s Nuke.

Layer-based compositing represents each media object in a composite as a separate layer within a timeline, each with its own time bounds, effects, and keyframes. All the layers are stacked, one above the next, in any desired order; with the bottom layer usually rendered as a base in the finished image.

Layer-based compositing is very well suited for rapid 2D and limited 3D effects such as in motion graphics, but becomes awkward for more complex composites entailing numerous layers.

Nodes or Layers: Which is better?

To be honest, there is no right or wrong answer. They both can achieve the same effects. Software preference will factor greatly into your decision. The more that you use one software type, the more you will become accustomed to that system. Just remember that layers are not great for huge projects with many items and effects; likewise, projects with little footage and few effects are sometimes not the most efficient for nodes. What it really boils down to is personal preference. A great rule of thumb is go big and go nodes or keep it small and stick with layers.

EXTRA CREDIT

Here’s a nice article, written by Wéland Bourne, explaining the differences between these two systems and comparing different effects software.