# 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](../static/import-mode-dropdown.png) ## 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 | !!!success 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](../using/animation.md#add-animation) — 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](../using/animation.md#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. !!!info 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](../reference/performance.md) 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](../using/eyes.md). ## 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](../using/wrinkles.md). * **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](../using/hair.md). Everything else — including **displacement** — works in both modes. !!!info Mixing sources The animation database accepts **both FBX and USD motion clips, in either import mode** — and USD clips are far lighter (see [Animation](../using/animation.md)). 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](preparing-your-character.md) covers how to export for **both** modes.