Hello guys I don't understand why if I apply a subdivide node to a poly sphere it gets subdivided, if I connect the same subdivide node to an Alembic file geometry it doesn't work … it happens the same with other nodes, for example the uvedit node, on the sphere it works, on Alembic it doesn't. Anyone can help ?
Thank you

Ray

You have to use an Unpack SOP to convert the alembic primitive in to actual geometry that you can apply a Subdivision SOP.

Alembic primitives along with Packed primitives are archive type primitives. Houdini doesn't own the geometry, just the point that defines the primitive. The geometry is sent directly to the OpenGL viewport bypassing Houdini. Houdini updates the point primitive attributes to OpenGL to update the geometry. This is how the Transform SOP works as for packed prims and alembic prims the intrinsic point transform is sent to OpenGL to transform the geometry.

Using MiddleMouseButton on the SOP tile will give you the operator info and there you can see only the points par archive, not the points for the actual geometry.


Having said that, there is the Alembic Subdivisions on face sets. Is that what you want to work with? Or is it physically subdividing the geometry?

Thank you for your reply Jeff, I have tried using unpack node but it still doesn't work. Strange is Mantra subdivision at rendertime works fine without unpack. Maybe I'm doing something wrong importing the alembic file ? I just create a geo node, delete what's inside, create an Alembic node and import the abc file.

Anyway I need to use it just to see subdivision in the scene view, during rendering it works fine using Mantra subd at rendertime

Ok I think I got it, I connected an unpack sop node, then a convert sop (to convert from poly soup to poly), and finally a normal sop because subdivided model resulted faceted. A bit complicated for having a subd preview in the viewport, in Maya you just need to press “3” …