Concerning game asset pipelines:
Has anyone developed a system in Houdini that can ingest a model from a place like Turbosquid and spit out said model to Unreal or Unity with things like LODs, all while maintaining all hierarchy and transforms? Creating LODs is easy enough with Labs tools, but maintaining all hierarchy and transforms... That seems to be the hard part.

Use the fbx exporter (sop or out are fine). Set the a name attribute to follow the naming convention of automatic seeting LOD in either UE or Unity (mainly adding "_LODx" suffix. There is a "build hierarchy from path" function in the fbx exporter of unity. Using that when exporting the mesh, houdini will split the geometry into different objects according to the primitive attribute you set. The name of the object will be the string value of the attribute.

If you have multiple objects with LODs inside one fbx (e.g. a_LOD0, a_LOD1, b_LOD0, b_LOD1. c_LOD0, c_LOD1, all in one fbx), you will probably need to script the engine to set the lod.

Thanks for the tips. I should have mentioned that I am familiar with the path attribute for rebuilding the hierarchies. The most challenging part for me is to maintain all the transforms as well as hierarchy. Houdini wants to make all the pivots centroid, which is not what I'm wanting. I've tried copying over intrinsic attributes from the original FBX import, but this seems to create wonky exports in Unity even when everything looks correct in Houdini. I am able to maintain all the original pivots and transforms when I import objects that have no hierarchy, strangely.

So I can get it to export hierarchy using the path attribute, and I can get it to maintain transforms if exporting with no hierarchy, but I can't have both! It's definitely a head-scratcher.

andylewisart
Thanks for the tips. I should have mentioned that I am familiar with the path attribute for rebuilding the hierarchies. The most challenging part for me is to maintain all the transforms as well as hierarchy. Houdini wants to make all the pivots centroid, which is not what I'm wanting. I've tried copying over intrinsic attributes from the original FBX import, but this seems to create wonky exports in Unity even when everything looks correct in Houdini. I am able to maintain all the original pivots and transforms when I import objects that have no hierarchy, strangely.

So I can get it to export hierarchy using the path attribute, and I can get it to maintain transforms if exporting with no hierarchy, but I can't have both! It's definitely a head-scratcher.

Using path attribute only support a certain amount of transform with packed primitives. If you want full control of the transform and pivot. You will need to write a python script to split the geometry into different geometry node and wrap them into a subnet then export them. Then you can edit the transform of the geometry node. I did that serval times before and it works great if there are not too many objects (say <100).

Anyway python will be your friend.

For maintaing transform form imported fbx, I saw some articles online about it before but unfortunately I can't remember where I saw them