Object Properties And Displacement via Sops?

[daeschri]

When working in Maya and using displacement, we can apply the displacement via the displacement node set.
No matter where the mesh is in the outliner hierarchy or if its moved it still remains part of the displacement set and gets the displacement map regardless of shader.


In Houdini we can get a similar result by adding the object properties to the desired geometry container in the obj context and then using the displacement options in it to apply displacement.

This is not ideal or as useful as we often object merge the contents of a geo container into another geo container etc before it's rendered.
When we use this method the displacement of the original geo is now applied only to the original geo container that has the object properties.
So in Houdini adding displacement via object properties is not really usable unless the rendered object is the geo container with the object properties.

My Question is this, can we have an object properties sop?

Applying object properties via sops to packed objects would provide a better Houdini experience and similar workflow to what we have in Maya.
By this I mean regardless of obj network location, changes via object merges would not impact the displacement.
It would now come along for the ride just like material assignments currently do if assigned via material sops.

We can always use displacement via material assignments, but we'd like the option to keep using displacement without it being tied to the material.

Any chance that object properties or settings like displacement could have a Sops option? Or is this not a possibility in Houdini?

David Eschrich
CG Technical Supervisor
Zoic Studios.

[chakarov]

Hello daeschri , we are thinking of support of obj/hair/displacement properties assigned via attributes, but because this is not easy to implement. So in first place we want to collect data from users which properties they need the most. Can you share a list of obj/hair properties which you and your studio wants to be supported via attributes.

[daeschri]

I'd request the ability for any parameter that is on the object or hair properties to be optionally created via sop primitive attributes. But to start, subdiv and displacement options would be great and the most critical for us.

[bdancer]

Those properties only make sense for the whole "object" (e.g. you can't set geom_splines=1 for one hair strand and geom_splines=0 for another)... so basically my question is - will this be ok to work for packed prims only?
Cause I'm really not sure how to process if those will be applied per-polygon...

[daeschri]

Packed prims will absolutely work. In this example I'd be using a packed prim via delayed load alembic. Being able to add some kind of attribute to drive what gets subdivided at render time would speed up our workflow. In this example I have 4 packed prims and I only want 1 of the 4 packed prims to be subdivided at render time.

[ronald_a]

just to add my 2c:

even beeing able to tell which packed abc gets subdivided and which not would be great.

it would also be nice if you could provide a sop which does the attribute assignment(pretty much with a similar ui as the displacement properties). one could of course build such an hda but having it directly in vfh would mean that any updated funtionality (e.g. new parameters) would be visible to everyone using the sop without combing through the forum or some releasenotes to see what attributes are available.

[daeschri]

Has there been any further consideration around this topic? It would go a long way to improving life with vray in Houdini.

[ronald_a]

This has been in there for a while now

[bdancer]

> This has been in there for a while now

SOP object properties node is also there for quite a while - have you tried it?

[daeschri]

Well, this is great news and no, haven't tried it as I didn't know it was implemented. Must have overlooked any communications mentioning it was added. I'll be asking the team to give it a go. Thank you!

[daeschri]

So far this is doing mostly all what we needed. A huge thank you.

Can you confirm the workflow for specifying a texture to be used for displacement with this method though?
I don't see the texture field to specify it in the objPropSop.

Instead I'm applying displacement within the material, and then I'm using the prim attribute vray_displ_use to toggle what gets displaced or not. It this the intended workflow?

Or are we able to set the texture path using the objPropSo or some other vray attribute?

Again, this is a huge gain overall. Very happy to have this ability to set attrs via sops and get what we want.

[bdancer]

> Can you confirm the workflow for specifying a texture to be used for displacement with this method though?
> It this the intended workflow?

Yes.

[bkirch]

Which release build of VRay for Houdini was this feature implemented in? Is there any documentation? We are using Houdini 18.5.596 and VRay 5.10.20, which is dated Jun 2021. I realize that is much older than the dates of this thread.

[Gosho.Genchev]

Hey bkirch ,

The Object Properties SOP was introduced between 08-15 March, 2022 in the nightly builds. Additional fixes were implemented in the following week. Builds from April, 2022 would include all the fixes.

I've added a ticket for our documentation team to prepare some additional info.

Best regards!

[tsvetomira.girginova]

Dear bkirch, hello.

Just to mention, if you experience any difficulties of finding the needed nightly builds or there is a lack of access, please contact our Chaos License Management Team via our contact form and choose respectively License Management under Request Type.

Kind regards,
TS