USD vs FBX

Version 1.2 added a second way to import your character. At the very top of the node is an Import dropdown with two choices — USD (the default) and FBX. Both produce the same shaded, animatable character with the same lookdev controller; they differ only in import speed, memory use, and a few features that depend on data Character Creator writes to one export but not the other.

The Import dropdown at the top of the Reallusion Importer node

TL;DR — what you get from each

	USD (default)	FBX
Import speed	less than a minute, even for HD characters	1 - 3 min (grows with character weight)
Memory (one loaded character)	less than 8GB, even for HD characters	~10–40 GB
RAM to plan for	16 GB min / 32 GB recommended	48 GB min / 64 GB recommended (HD)
Skin Cache needed?	No — USD loads fast without it	Recommended for heavy/HD characters
Geometry, skeleton, body + facial animation	✅ Full	✅ Full
Materials (skin, eyes, teeth, hair, clothing)	✅ Full	✅ Full
Subsurface, displacement, retarget, Split Body/Facial, Skin Fix, render rig	✅ Full	✅ Full
Real CC eye & skin values (iris color, iris size, limbus, sclera, SSS)	✅ Read from the file & auto-applied	⚠️ Not exported — generic starting defaults
Expression wrinkles	❌ Not in the USD export	✅ Yes
Hair root-to-tip ombré + highlight streaks + flow sheen	❌ Maps not in the USD export	✅ Yes
Hair flat re-dye + Lightness (Bleach)	✅ Yes	✅ Yes

Bottom line

Use USD for almost everything — it's far faster, far lighter, and better at eyes/skin because it carries Character Creator's real shader values. Switch to FBX only when you specifically need animated expression wrinkles or the full hair re-dye (root-to-tip / highlight streaks).

The best-quality workflow

An FBX character driven by USD motion clips. The expression wrinkles are the single feature that makes a Character Creator face read as alive in motion, and they're FBX-only. So when the look matters, don't treat this as an either/or:

Import the character as FBX — you get the expression wrinkles and the full hair re-dye. If all of its motion will come from clips, export it Mesh only.
Drive its animation with lightweight USD motion clips from the animation database — a USD clip loads instantly and costs almost no memory, where each FBX clip costs several gigabytes. USD clips drive an FBX-imported character perfectly (the tool turns Retarget Animation on for you, since the two formats bind different rest poses).

That combination keeps the FBX-only look features while your animation stays featherweight.

An honest caveat

This is the best-quality path, not the lightest one. An FBX-imported character is memory-heavy no matter what — that's the cost of carrying the wrinkle data, and it's unavoidable if you want wrinkles. What the USD clips save you is the animation cost: you avoid holding a heavy FBX clip (or a long baked-in FBX animation) in memory on top of the character. If you don't need wrinkles at all, a plain USD import is the lighter choice.

Why USD is so much faster and lighter

Character Creator's FBX stores every facial blendshape as a full mesh copy, and Houdini has to expand all of them on import — tens of gigabytes of RAM and a minute or more on a heavy HD character. The USD export keeps those blendshapes sparse, and the tool keeps them sparse through deformation too: only the expressions actually active on the current frame are computed. On the heaviest HD character, working footprint drops from ~26 GB via FBX to under 8 GB via USD, and raw import time drops from a minute and a half to about a second — the gap grows the heavier the character. Because USD loads so fast, the Skin Cache is unnecessary there and its controls are hidden. The only trade-off: scrubbing a very heavy HD character recomputes its face each frame, somewhat slower than FBX's cached playback — a fair trade for fitting on a normal machine.

What USD does better — real Character Creator eye & skin values

The FBX export leaves out most of Character Creator's HD eye shader, so in FBX mode the eye controls start from generic defaults you dial in by eye. The USD export carries Character Creator's actual shader values, so in USD mode the tool reads them and seeds the controller automatically — real iris color (when CC actually tinted it), iris size and limbal ring, and sclera shading and subsurface amount from the real per-character values. It's all still adjustable; these are just smarter starting points, and Reset to Defaults returns to them. See Eyes.

What USD mode does not carry

Character Creator's USD export omits some data the FBX export includes. Where that happens, the affected controls stay visible but are disabled with an "(FBX import only)" note — nothing is hidden or silently broken.

Expression wrinkles — the animated head-wrinkle system is FBX only; the USD export contains no wrinkle maps or weights. See Wrinkles.
Root-to-tip and highlight hair re-dye — Character Creator's USD export leaves out the hair root, ID, and flow maps, so the ombré recolor, highlight streaks, and flow-based sheen are FBX only. A flat re-dye and the Lightness (Bleach) control still work in USD. See Hair.

Everything else — including displacement — works in both modes.

Mixing sources

The animation database accepts both FBX and USD motion clips, in either import mode — and USD clips are far lighter (see Animation). USD binds in a T-pose while FBX binds in an A-pose, so when a clip's format differs from the Import mode the tool turns Retarget Animation on automatically. A character driven by its own embedded animation is always correct.

Switching modes

The Import dropdown swaps which file field is shown — CC5/iClone USD or CC5/iClone FBX — and rebuilds accordingly on Build Character. You can switch an existing node between modes any time; just set the matching file. Scenes saved before 1.2 load in FBX mode automatically, so nothing you built before changes.

Next: Preparing Your Character covers how to export for both modes.