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Houdini to Unreal Heterogeneous VDB Pipeline

//Unreal Prerequisites for Houdini -


  • Scene positioned at 0,0,0 or close to 0,0,0 (world space)


  • Single animations on single layer or single actor, no multiple animations on multiple actors. If absolutely necessary, bake down animation 


  • Start Sequences from frame 1000 - gives time for sim preroll (Houdini does not like negative frames)


  • Scene cleanup (Disposing assets not needed in the level). Heavy scenes create problems when rendering heterogeneous volumes and cause glitches.


  • Preferably avoid use of blueprints, Blueprints are not recognized / interpreted by Houdini.


//Troubleshooting Unreal Scenes - 


  • Check if hardware ray tracing is on/off


  • Check if Nanite is on/off on terrain


  • Check compatibility of assets with Unreal Versions


  • Check if volumetric shadows is turned on/off for lights in Unreal


//Houdini to Unreal VDB Pipeline - (Example .hip download (Simulate at Origin))


  • Import models into Houdini with convert units checked on in filmbox FBX dialog box (Houdini will scale down the whole scene by 100 units)


  • Extract transform and rotation and simulate at origin, use match size in the end to reapply xform transformation


  • Export VDBs out of Houdini by multiplying sim cache by a factor of 100


  • Import into Unreal, input into VDB material and add it to a heterogenous volume


  • When importing into unreal, change values as follows - Rotation (90, 0, 0) and scale (1, -1, 1)

  • Attach heterogeneous volume to the actor to reapply lost xform transformation




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