You can use a few other software to do this, but the current solution in Houdini is pretty good as well.

Labs Maps Baker node, a nice solution.
Download the latest update via the SideFX Labs shelf. After that you will find the node.

This method is a relatively fast way to get better Height map from the existing high res. geo, to use as a displacement map on the also existing LOD0 geometry.
This is not ideal because the high res. model is usually not match well to the LOD models (in terms of form) for open objects (the closed ones are good), also the high res. model is not enough high res for displacement baking.
note: The best way would be the ZBrush way: download the ZTool than redo all the proxy generation and displace baking part (way to much time) but that should give you the best possible result.

STEPS

  1. Create two file nodes, one for the LOD0 and one for the High res.

  2. Add a normal node after the LOD0 file node

  3. Add a subdivide node after that (OpenSubdiv Catmull-Clark, depth: 2).
    This is necessary to match the later subdivided positions of the vertices and normals.
    Without this you’ll get visible artifacts.

  4. Connect the the two results into the Labs Maps Baker node. LOD0 branch goes into the first, high res branch goes into the second input.

  5. Save the Houdini file

  6. Turn off all unnecessary parts (Vertex Color, AO)

  7. Turn on the Height part and switch to EXR

  8. Select the resolution, 4K should be enough (again, not enough data on the high res. geo).

  9. Bake

You can create a simple HDA from this. I did. :)

The result will be a black zeroed displacement map so use the map accordingly.
In this case I check the results in Maya/Arnold.
The EXR is used with a Displacement shader.
Settings: Out Alpha, Alpha Is Luminance: On, Alpha Offset: 0 (because the the non-displacing value is the black, Displace Scale value: 1, geo subdiv: 5, Auto Bump: On).
For the rendering check, I also turned off the Normal map intensity for both shader.

The high res geo (left) vs the LOD0 geo with displacement preview in Maya (with the rebaked displacement map).

Arnold render

Looks perfect to me. :)

Cheers, D

LABS MAPS BAKER FEATURES

  • Transfer maps form one geo to another (different UVs, similar objects)
    Diffuse Map, Normal Map, Opacity Map, Roughness Map, Metallic Map
    You can use custom naming convention as well.

  • It’s pretty robust (although it could be much faster), so you can transfer maps form hires to hires (scanned objects, very high resolution geometries <about 20 million polygons each>)

  • Generate, bake maps: Vertex Color, AO, Thickness, Curvature, World Normal, Height (aka Displace), Alpha, Position, Material ID

  • Multi Frame feature

  • Different Tracing Modes

  • Custom Cage Geometry

  • Custom Attributes

  • Automatic UDIM support

  • Currently the maximum texture size is 8192 px