Weight Map (XSI) to Houdini /PyroFX

[marc0s]

Hello together,

I am quite new to Houdini (indie) and most of the informations I can find by searching the board.
So thx for the mass of input and that great application. Gave us some pretty nice results in the last time we never had before!

Anyway - since I/we still use alot Softimage and many of my fellows do only work with it, the addoption takes some time and like right now, I got some weight map stuff from a friend I have to use.

I'll attache (if it works, otherwise put a link below the text) a video of the weight map for more understanding.
Actually, the weight map shall control PyroFX emission.

My first thought was, to create an animated texture map of the weight map and use that to control the PyroFX emission.

But maybe there is a smarter way to get the weight map + the geometry into houdini - Alembic with vertex attributes maybe?
I already tried that and of course, stuck on getting the attributes of the weight map into the alembic file and import that into houdini and again getting the attributes to create a weight map in houdini.

Another way that works but is very slow and rough: emitting particles in Softimage, using a Polygonizer and export the geometry as an alembic file.
Or, but there I again stuck, just exporting the particles from Softimage into Houdini and emit Pyro from these particles.

What would be one good way?

Thank you very much and have a nice weekend

marc0s
 

Weights Grow.m4v

[merlino]

Marcos, I think the easiest way is to export the alembic with the weight map as vertex colors. Then when you create the fuel source (your "fluid source" node after the emitting geometry) you should set "Scale by Source Attribute" ON and set "Cd" as source attribute. It should works this way. Maybe you should promote the Cd attribute from vertex to point, but I'm not sure it's necessary. Let me know if it works! 

Cheers,

Marco

[marc0s]

1 hour ago, merlino said:

Marcos, I think the easiest way is to export the alembic with the weight map as vertex colors. Then when you create the fuel source (your "fluid source" node after the emitting geometry) you should set "Scale by Source Attribute" ON and set "Cd" as source attribute. It should works this way. Maybe you should promote the Cd attribute from vertex to point, but I'm not sure it's necessary. Let me know if it works! 

Cheers,

Marco

Hey Marco,

thx for your reply.

Just trying to find out, how to store custom attributes from Softimage in Alembic, to import them in Houdini.
Exporting the geometry as alembic gives me zero custom attributes in Houdini. The middle mouse Button over the the alembic geometry should tell me, if there is a custom attribute, right? Or do I have to copy the attributes first?

So when I figured out, how to store attributes from ICE into Alembic, I'll test that.

marc0s
 

[Atom]

You may have to actually unpack the Alembic before the middle-click will reveal the attributes. Drop down an Unpack after the Alembic node then middle click on the Unpack to inspect attributes.

[marc0s]

ah okay, thx - at least I get one more attribute beside the Point Attribute (P) - a Primitive Attribute 'Path'.

 

[marc0s]

okay, just found out, that softimage does not support exporting color/vertex on a Polymesh:

Quote

NOTE:Softimage supports exporting only the following object(s) to Alembic format:

PointCloud — Shape instancing, particle animation through ICE attributes (position, color, size, orientation), and most of the ICE data types

PolyMesh — Shape animation, UVs, FaceSets

Null rig

 

So, maybe a solution would be emitting from pointcloud? I could create a pointcloud thats based on the weight map.
Than convert the points to VDB or something would be my first idea....

 

[Mandrake0]

maybe you can try the PLY file format?

it supports custom attributes and you can check the file with the editor it has exported the attributes.

[marc0s]

1 hour ago, Mandrake0 said:

maybe you can try the PLY file format?

it supports custom attributes and you can check the file with the editor it has exported the attributes.

the problem is, that I dont get the custom attributes exported - at least not on the mesh. Exporting ICE Particles with custom attributes is working just fine, but on Polymesh not.

[marc0s]

ahhh, exporting/importing vertex from Softimage is even more easy than I thought
I just had to convert the weights to vertex first and export as FBX.

So, I finally have a grid with Alpha, Cd, and N attributes.

Like Marco mentioned, I set the " Scale by Source Attribute" at the geometry under "SDF from Geometry".
But where to put the Source Attribute? In the "Source Attribute" (green)?
When I do this, nothing happens. How can I find the link to the original density (since its green, the density is set somwhere else?)?
 

I attached the vertex.fbx, but I think, thats correct since I can see the Cd attribute.

vertex.fbx

[merlino]

You almost did it! Just few more steps:

Do the "attribute promote" of "Cd" from vertex attribute to point attribute before the "fluid source" node.

To clear the linked value (green) do CTRL+Shift+LMB on that greened "density" and put Cd there.

It should works

[marc0s]

yes!!!

that was easy actually, hehhe.
Now I just have one more problem, but that seems to be a Softimage problem.
The FBX does not save the vertex animation, only first frame... either I find a solution for that, or Ill bake the vertex into a texture map sequence...
Lots of work do get it done, but lots of learning, too.

Now, since I understand how to promote from vertex to point attribute, it shouldn't be a big problem to promote from texture map sequence color to point attribute.

thx alot for the lesson