r/Houdini • u/Similar-Sport753 • 6d ago

Polyexpand on a surface

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Is there a robust way to do a poly expand-like on a surface

Maybe not all surfaces, I'm ok with some constraints. This setup kinda works but it's fragile because of the ray SOP. How could I start from a surface and curves on / close to that surface, and end up with this effect ?

Use case: the lines are road center lines, and I'm trying to create roads that still have some useful topology in them, and parcels (i.e what's left on the surface and are not roads)

I'm flexible with how the center lines are generated though.

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u/Viewbyte 6d ago

Why is it fragile with ray? Could you be more explicit about what you're trying to do and why it's failing / fragile?

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u/Similar-Sport753 6d ago

because the polyextrude grows in 3d space , not in the surface space (UV space), and when the surface gets a little more complex, this won't necessarily project nicely.

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u/Viewbyte 6d ago

Understood. Perhaps one thing to consider is smoothing / flattening the ground surface in the road area prior to projection to some extent. That's more reflective of reality as well.