Edit Review: Autodesk Combustion 4

Combustion 4 is the latest upgrade to the Autodesk's popular compositing program, one that is increasingly influenced by the company's hardware-based systems, Flame and Inferno. This is a good thing because Combustion fits in comfortably as a backroom graphics option at facilities based around what are probably the most successful high-end compositing tools in the industry. Combustion has also gained traction in the pure desktop market, partially because of its RPF integration with 3ds Max.

Combustion 4''s new Diamond Keyer provides advanced control and algorithms for changing the color of an object in a scene.

A little background first. There are two ways to represent processes in a compositing program: layer view and schematic view, also called a process tree or node-based view. After Effects uses layers, while Combustion, Shake, and Nuke use nodes. Combustion's schematic view is elegant and exposes the flow of data in a complex shot. Combustion calls the effects applied to the data Operators. Proponents of layers or schematic-style layouts are not given to moderation in their likes and dislikes. For them, it's a matter of habit and preference. In the end, this is not a quality issue — it's all about workflow.

C4 is a mid-sized release; nothing earthshaking, but it provides a few big features and enough small enhancements to make upgrading an easy decision. In short, there are no major changes to the product, just more value overall to a product that is a powerful and mature compositing tool. There are no major holes in C4's capabilities and at this point the product can handle any VFX or motion-graphics project that you can throw at it.

One of the easiest new features to understand is the Diamond Keyer, which is based on the Color Warper tool in Flame. The Keyer is useful for isolating elements in a scene for special color treatment or other effects. Previously, Combustion users turned to the Discreet Keyer for these types of effects, but the Diamond Keyer has more sophisticated control and algorithms. However, while the Discreet Keyer also had matte cleanup tools built in to the main key controls, the Diamond Keyer does not. It's not a big deal, though — you simply add Operators, Matte Controls, and Spill Suppression to perform these final refinements.

If you were using the Diamond Keyer for look development, one of C4's other new features, Capsules, will be very useful. Capsules are collections of Operators. A Capsule essentially is a template of effects designed for a single particular end result that might be useful in the future. One example might be the isolated color effect from the movie Pleasantville. The Diamond Keyer and other operators could be used so a person's face is the only color in a black-and-white scene. You could save the Operators for the finished shot along with their parameter settings as Capules to be shared with other Combustion artists. In the past, you would have had to save an entire project to accomplish the same kind of archiving. Capsules are small in size and easy to send over the Internet or a network. Unfortunately, Capsules are not recognized by Flint, Flame, or Inferno, which is an odd oversight, considering that the programs are often part of the same pipeline.

C4 has also added the Timewarp Operator. This is a basic time-remapping tool for changing the speed of footage. The time effects can be keyframed to allow for dynamic slowdowns and speedups. They include specific interpolations such as Skip Repeat, Blend, Adaptive, and Trail. Time remapping is accomplished through frame blending or frame repeats/skipping, but not with more sophisticated per-pixel vector analysis that allows for the creation of interpolated frames. This is typically added through the use of third-party plug-ins such as Re:Vision Effects Twixtor or the Foundry's Kronos. For now, C4 has all the basic time-remapping algorithms that are useful for many situations, but not the higher-level slo-mo effects that were added to After Effects in version 7.0.

RPF and RLA file formats are generated in 3ds Max and contain a G-buffer (graphics buffer) with in-depth information from the 3D scene. This allows 3D scenes to be brought into Combustion and effects and special 3D post filters to be added in Combustion while operating as though they were applied in the original scene. For example, a glow could be added to a police car's flashing lights in a profile shot as the car speeds through the woods. The camera might be tracking from within the woods. The glow should be obscured by foreground trees but visible in front of background trees. If this is a 3D scene created in Max, you can add the glow in Combustion, and RPF files will supply the depth information to properly occlude the glow. This is a powerful capability and even allows for the relighting of scenes. However, files from other 3D programs may not have a G-buffer. C4's G-buffer builder allows you to add this capability to other file formats, including video footage.

Combustion has had Bezier controls for masking, drawing, and selecting, but now C4 adds B-splines to the toolset. B-splines use fewer parameters per point compared with Beziers, but choosing which one to use is job-dependent and a matter of practice. In any case, C4 now allows you to decide which tool is best.

Point grouping is another new feature that is a clear winner for anyone doing rotoscope work. PG lets you mask an entire shape and then select a group or subset of the entire mask and make it a separate selection. Typically in roto work, the best way to mask a moving object that changes shape, such as a walking character, is to create an outline for every articulated shape — in this case the arms, legs, head, and torso. You set the pivot point for each shape so that it operates like a character model. Shapes are moved and rotated to follow the character rather than rotoscoping the person as a single shape on every frame. This way you are creating an animated character out of individual roto shapes. Point grouping gives you a tool to do this easily, and the individual shapes are parented to the main group.

C4 also adds a number of small features that are obvious plusses, such as grids, rulers, and guide lines. Shapes and objects can be snapped to any of these guide tools, but curiously, text is the exception. However, for motion graphics, these are essential tools. A small feature I really like is the Compare tool. This was previously available in the color corrector but is now present in every viewport. Compare allows you to save five settings or Operators and view them simultaneously. This is more than a frame store because you can preview moving footage. You can split the frame horizontally or vertically, with a different version of your footage running on each side of the split. Or you can draw a rectangle selection on any part of the frame. This is enormously useful and, frankly, an essential tool in any compositing program. C4's implementation of the Compare tool is a feature you can expect to use all the time.

A studio-level feature that will be welcome to IT and render TDs is command-line rendering. Now you can control renders from outside of Combustion.

Most users will upgrade for one or two of the bigger features such as the Timewarp Operator or Diamond Keyer. This is a full-featured product that is capable of providing all the compositing power necessary for a boutique motion graphics or VFX shop. It is a particular favorite of artists with Flint, Flame, and Inferno experience for obvious reasons. The learning curve is a bit steep and the node-based approach is not for everyone, but this is an excellent product and one of the best tools in its price range.

Company: Autodesk
San Rafael, Calif.; (415) 507-5000
www.discreet.com

Product: Combustion 4

Assets: New Diamond Keyer, Timewarp Operator, and point grouping.

Caveats: Steep learning curve. Node-based approach may not appeal to all.

Demographic: Motion graphics artists.

PRICE: $995
($249 UPGRADE FROM 3)