New to Houdini. Reading tutorials, etc. But this one has me and the instructor stumped.

I've created a simple flat nurbs curve, mirrored, joined, extruded, removed caps, and added a Refine to subdivide the edges along V (first V = 0, sec V = 1, divisions = 3). Finally, I added an Edit node and scaled the middle cv's of the edge division outward to create a rounded edge. Instead of a nice curve developing from top to bottom, we're getting a sharp, faceted “V” shape. We can see no adverse settings in the network to account for this. The effect is the same as if the tangent handles on a bezier curve were made discontinous or “broken.”

Any ideas how to get rounded edges on an extruded shape? Using a Round sop doesn't work. Making a nurbs box with similar divisions and adding Round to it kinda works, but the two “halves” of the rounded edges can't be made to “join” exactly in the middle without the round results going haywire.

The object being made is a Waccom 6 x 9 tablet, so the end result has a thin profile with rounded corners and rounded edges. Rounded corners, no problem… rounded edges… problem. Of course, due to the UV nature of the object, Fillet or Bridge won't work cleanly around the entire edge, thus the reason for trying Refine on a curve extrusion.

Thanks for the your help.

Dean Scott,
SCAD.

Hi Dean,

Houdini's viewport has a low default Level of Detail setting that causes Nurbs curves/surfaces to display in-accurately sometimes. Type ‘d’ in the viewport, go to the Viewport tab & increase the Level of Detail until you are satisfied.

Of course, if the above doesn't help, post a reply & we'll take it further.

Cheers!
steven

stevenong
Houdini's viewport has a low default Level of Detail setting that causes Nurbs curves/surfaces to display in-accurately sometimes.

Thanks, Steven. I'm not convinced that this is the issue since the same sharp edges show up in the render. The render's shading also shows the edges to be “detached” from the top and bottom caps of the extrusion, that is, where the caps and the extruded edge meet does not have a smooth shading that blends the angles… it's very sharp as though the cap and the edge where separate objects. I come as a 10 year user of Lightwave and in it this is called the smoothing angle. So, even though the angle formed by these two surfaces is less than 90 degrees, the shading is sharp as though it were greater than 90 deg. Even the default box created with a new geo shows up in OGL with strange shading that indicates the edges are being smoothed over… that is, not sharp.

Even though that's part of the problem, the main concern is getting the nurbs curves formed by scaling out the central cv's of the extruded edge to be curved and not straight segments.

Now, we can get something of an acceptable result by setting the Refine sop to 5 divisions verses 3, scaling only the middle row of cv's, converting to polys, which makes a really dense mesh on the edge, then smoothing, but I'd rather keep this as nurbs-only.

Is it possible to extract part of your SOP network & copy-n-paste that into a new hip file & post the hip file somewhere? Please zip or archive it before posting because sometimes Netscape or Mozilla likes to expand the hip file as text which messes it up.

I can take a look at it & I'm sure some others will too.

Cheers!
steven

stevenong
I can take a look at it & I'm sure some others will too.

That shouldn't be neccessary. I was able to find another way to model the tablet… used a box with the neccessary subdivisions and edited the heck out of it.

However, do the following…

make a grid or circle, extrude, add a refine (no U and play with the V silders and/or divisions), then scale out the middle cv's.

Compare the result to this method…

make a grid or circle, duplicate so there are three of them spaced apart, skin, then scale out the middle cv's on the edge.

If you look real close at the cv's of the first case, those associated with the V isoparms of the edges are farther offset than the rest along the edge of the extruded shape, a circle for example. Now the cv's for the skinned method are all evenly offset above the surface.