a simple task and the basics of Houdini

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Joined: Feb. 2019
Hey there!
I already tried Houdini a few years ago but sadly i gave up because of the wrong approach to understand the software.
Now i try it again with more simple steps

I have an interesting "challenge" to transfer lowpoly uvs to highpoly.

I made a nurbs model in fusion 360 so i don't have any low level subdiv cage mesh that i can uv unwrap.

My goal is to texture the highpoly mesh (exported from F360) so i can use it as a nanite asset in UE5.
To achieve this i will export a "lowpoly"/editable version of the mesh (100-200 thousand tri)that i can uv unwrap (by hand)

The Houdini part would be to import the lowpoly (LOW) and the highpoly (HIGH) meshes and then do these operations with them:

I know this is easy to any Houdini user who understand the building blocks of Houdini.
I already watched lot of videos years ago about the basics, and also tried to achieve some results, but as soon as i reached the expression part (especially outside the VEXBuilder) i just lost because of the to many possibilities.
I see a lot (to many) values and channels that can be edited and i just can't see the system in that ocean of data.

For example if i'm using fusion360 i see the main categories like sketch/body/form ect
In Substance Designer i can see all the nodes and even in the function editor i can see the main categories.
But in Houdini i totally lost because an asset can much more parameters and channels, connections than anything else in other 2d 3d programs.

I literally can't see how can i build up a proper graph because.
For example how can i get the COG info of a polygroup of LOW, and how can i manage to shot a ray from that point and hit the cog point of a polygroup of HI.
I just don't see what are the parameter list of a 3d mesh, and how can i "tame" them.

Maybe a good tutorial video or documentation would help but what i already saw just gave some hints and examples, but not the big picture.
I know Houdini is a much more complex software comparing to F360, i just don't see how can i start solve my "own problems" in Houdini

So my main question is, how should i break up my little task into Houdini building blocks, how can i see what blocks i can use (the what should i use maybe a bit simplier)?

Thank You if You read this , and for you answer in advance!
Edited by ostyascukor - May 10, 2022 18:02:37

q1gl.jpg (1.2 MB)
uv_lo2high.jpg (136.7 KB)

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Joined: May 2017
okay i am confused, why would you unwrap model by hand from an F360 export if the built-in export of fusion to .obj gives you perfect UVs? All you need to do after that is UV Layout, where you can pack them automatically, and even pack into UDIMs if you choose to do so.

i understand that does not actually answer your immediate question, just i am puzzled why make it hard, if your endgoal is Nanite mesh, and say Substance Painter will do just fine with millions of polygons and UDIMs
https://twitter.com/oossoonngg [twitter.com]
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Joined: Feb. 2019
You have absolutely right! I didn't even check it if the mesh has uv by default
It's not even bad, but I wish there would be an uv seam controller in fusion to make it perfect.
If it wouldn't be a few million polygon i would happily sew and merge the uv borders together

I also want to use displacement and wide range of dirt and leak on the texture, and that can be seam sensitive easily!

Anyhow thanks for the tip, i'll use it like this way if i can't solve the uv transfer (or i just try to sew the few million polygon )
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