Efficient USD Export in Solaris: Separating Geometry and Animation

When exporting animated assets from SideFX Houdini’s Solaris, it’s easy to run into inefficiencies if geometry and animation are baked into the same USD file. In that setup, every frame rewrites the full mesh—even when the topology never changes. A better method is to split static geometry from time-varying animation data.

Step 1: Geometry Export

Bring your geometry into Solaris with a SOP Import LOP. Disable time samples and remove unnecessary attributes so only the static topology is written. Save this as a compact .usdc.

Next, set up a Payload Layer so the geometry can be referenced later without inflating your main file. Use a Payload LOP to attach the geometry to the correct primitive path, then write out a .usda as your main geometry layer.

Step 2: Animation Export

For animation, use a separate SOP Import LOP. Import only attributes that actually change over time (e.g., P, N) and skip topology data. Export these animated attributes with a USD ROP over your chosen frame range as a .usda.

Step 3: Combine in Solaris

In your final scene, pull both layers back in with Reference LOPs:

• One referencing the geometry USD

• One referencing the animation USD

Both should target the same primitive path. The static payload provides the mesh, while the animation layer applies time-sampled updates.

This setup keeps exports lightweight, modular, and scalable:

• Geometry is written once and reused.

• Animation layers remain small and efficient.

• Updates to either geometry or animation can be swapped independently.

By separating static and animated data, you cut down file size and gain far more flexibility when managing assets across a larger USD pipeline.