hi!
I don't know, probably it is a very stupid question.

subdivide SOP or render polys as subdivs is not working as expected on GRID.
I know it seems lame, but i just need it to work as it should work with maya or renderman.

The problem is that the grid corners are not rounded (see pic).
This prevents me for getting a rounded corner shape without deleting the corner points.

Other shapes are OK, only a simple polygonal grid behaving strange.

Yes I´ve noticed this as well and it happens at corner point that have only two edges connected. Is this really following the catmull clark scheme ? If I remember correctly s-div surfaces will subdivide and smooth any “open” edges. Actually I’ve seen this behavior in another application, mudbox, where it behaves the opposite meaning it will smooth out the edges that have a maximum of two edges connected to one point and crease the edges on any inner edges that 2 or more. The nicest way of handling subdivision that I´ve seen is MentalRay integration into XSI where you have catmull clark subdivision for quads in combination loop scheme for triangles. This basically means that for any triangles it will triangulate divide and for quads it will use regular division and it gives the user absolutely no poles that will pinch the surface. It would be nice to read a little bit more in-depth about Houdini subdivision other than what can be found in the manual. SideFX team?

Hi, bumping this quite old thread, because I couldn't find any info, other than this old odforce thread, with no clear answer either
http://forums.odforce.net/index.php?/topic/12184-subdividing-boundary-edges/page__hl__subdivide__fromsearch__1 [forums.odforce.net]

Catmull clark subdiv is supposed to smooth borders.
See http://th.wikipedia.org/wiki/%E0%B9%84%E0%B8%9F%E0%B8%A5%E0%B9%8C:Catmull-Clark_subdivision_of_4_planes.png [th.wikipedia.org]

I'd like to randomly unfuse points, and create cracks in the geo by subdividing, without preserving border edges. Subdivide and then Smooth op kinda works, but doesn't give maya's result.

Cheers
Vincent

Not a stupid question at all, not sure why the subd works differently in Houdini but have to imagine it has something to do with this being a completely flat shape.

If you want to make rounded corners without creating an ngon try these steps:

1. Take the existing grid and connect it to a bound sop.
2. Add upper and lower padding.
3. Knife tool to create holding edges.
4. Apply subd sop.
5. Delete everything but the top face.
6. (Optionally) Connect to a match size sop to 0 out its coordinates

You guys need to put it in the correct setting. Although it is counterintuitive I have to admit.

That could only be Houdini...

Sharpen Edge Boundaries to round them
Add SOP to remove geometry
and now in H20 - quoted from the sneak peak video... "Ability to sharpen heightfields with Heightfield Blur"

You couldn't make it up.

Mike_A
That could only be Houdini...

Sharpen Edge Boundaries to round them

It's because subdivision surfaces distinguish between edges and corners. So the "Sharpen Edge Boundaries" mode only sharpens the edges, leaving the corners rounded.

Seems ass backwards to me. Couldn't they have inverted the logic and had a checkbox for 'Round corners'?

Mike_A
Seems ass backwards to me. Couldn't they have inverted the logic and had a checkbox for 'Round corners'?

Maybe. There's three different sharpening modes for point attributes though, so I guess 3x checkboxes could get confusing as well as it would allow for several combinations that aren't meaningful.

Mike_A
and now in H20 - quoted from the sneak peak video... "Ability to sharpen heightfields with Heightfield Blur"

Sharpen and blur are nearly the same operation, except one has negative weights.