Having only a beginners understanding of construction using nurbs in Houdini, I wonder if someone could outline for me the correct worklow set of proceedures for creating a human form, (just the basic shape), in a “piece by piece” fashion. In other words how would one proceed from lathing some basic shapes such as the torso, arms, legs, head and neck, and then “join them smoothly together?

I have had good luck using the ”paste“ operator creating detailed head features and ”pasting“ them on a low density base surface, but trying to use the same operation for pasting, let's say, a head and neck onto a torso does not yield, for me, expected results.

I have been able to use the ”join" operator successfully, but have not been able to extract base curves from, let's say, an arm surface, project that onto the torso, trim the torso and then join the two together. Must be missing something.

Thanks,

Greg Smith

Hey Greg,

Have you tried using a carve sop to extract your curve?

You also might be interested in this thread over at odforce:

http://odforce.net/forum/index.php?act=ST&f=19&t=1389&s=2e12522fc81fb95ab7c69701a265d670 [odforce.net]

hth,
dave

i was also getting so frustrated with not being able to loft etc, thanks, im glad i found this thread.

does anyone know if you can simply skin some circles, cap - then fillet the edge? thats ideally what id like to do..

mta: make sure that you're working with profile curves. as for your second question, try putting down a nurbs box and then appending a round sop. is that what you mean?

hehe i edited my post just as you responded - i managed to get this bridging working, happy about that..

YES the round sop is exactly what i needed, thanks a lot - impressive result.

by profile curves do you mean those you create yourself, or extract with carve - i.e. able to be lofted?

i should have just checked the cap paramaters more closely - theres a rounding option ops:

houdini is worth every minute of it's learning curve 8)

Although I have read the suggested thread over at ODforum, and have tried numerous experiments, I cannot get the bridge or the join to work properly on my premade NURBS geometry, and have a lot of trouble with the “carve” operation. I'm sure it is something simply out of order on my part, but if someone could point out the error in my madness, I'd be really grateful.

Here is the process, step-by-step, that I tried:

Revolve a NURBS shape from a NURBS curve.

In the same SOP, revolve another NURBS shape from another NURBS curve

Invoke a “carve” operation on the first NURBS shape, extracting a profile, (sometimes this works and lets me grab one of the dotted profiles, sometimes not)

Invoke a “project” operation selecting the extracted curve profile and correctly orienting the project onto the surface of the 2nd NURBS shape

Invoke a “trim” operation on the 2nd NURBS shape, creating a matching hole

Invoke a “profile” operation and attempt to extract the curve that defines the hole on the 2nd NURBS shape, (don't think this works for me)

Invoke a “bridge” operation, selecting both curves to bridge between

Get a twisted mess for a connection, (if I even get this far)

I am creating the process in the Viewport, without really looking at the SOP network, so maybe I've done something out of order.

Thanks for thinking about this,

Greg Smith

with the carve, i selected the last V, and set it to 1 - this took the carve (extracted the curve) from the lowest point on the tube (using geometry like the ODforce page).

I didn't need to use a profile SOP, but to get this to work I had to turn on profile numbers (right hand side of viewport, below the show points, edges etc buttons.) then i saw that the tube was 1.0 and the grid 0.0 … i entered those into the bridge and voila!

the videos from sidefx and 3dbuzz are awesome, but only basic nurbs unfortunately. i read sidefx are releasing more videos late in the year, hopefully medium-advanced nurbs is one of them 8)

My example in that odforce thread uses 2 carve sops on the tube object.

first use was to extract 3d curves, so that I could do the trim.

Second use was to extract 2d profile so I could bridge.

I couldn't get it to work without extracting the second profile just for the bridge. However, I didnt try too hard.

After reading Shannon's post I remembered I also had to do the 2 carves on the tube, sorry for any confusion.

progress, but the same bridge SOP that made the tube work generates this on some real geometry



the round shape is a revolve, i first added a primitive SOP to that and rotated the seam away from where i trimmed.. this is the best looking i could get the bridge, tried many combinations of changes. i thought of trying a reverse on the outer spline in the bridge but this didnt help. it's probably something simple causing this but im out of ideas.