Fur and getting guides to work

[jim c]

By the way, if you don't mind, can you post how this works for you? I'd love to see more people posting about how they do this. There's almost no detailed info out there on this, which really surprised me when I started.

[jim c]

PS: there's more info here too,

[dobin]

The problem:

So at this point we are trying to get the hair that has been groomed in Maya moved over into Houdini in order to render it along with everything else. Converting it to polygons and exporting it is heavy and impractical at render time....

export splines from Maya in iges format...if you got spline animations you could write a simple mel/python script to export iges sequence of files and import them in Houdini using File SOP.

Edited August 18, 2011 by dobin

[Mister Fidget]

@ dobin:

Thanks for the suggestion. However, I haven't been able to get the IGES format to export anything other than the groomed NURBS curves hair guides (which I have already exported and imported previously with the FBX format). Besides, it isn't so much the hair animation I am trying to get out as it is the groom. The animation and simulation of the hair I can do in Houdini pretty easily. But I can't seem to get the Fur SOP or the Fur HDA to recognize the previously groomed curves as guides.

@ jim c:

Thanks jim. I have been able to get the Houdini generated hair guides to flow in the same direction as the original groom without much fuss using the flowfield SOP and your example file.

Original Maya groom:

Houdini groom:

Obviously, I haven't put in any time yet on shading, length maps, etc. But at least being able to get the general shape and flow is encouraging.

Sadly, I don't think the flowfield solution will work. I know that I can install the flowfield SOP on my user account at the school, but I don't have control over what the other students working on the shots will/can do. Also (and probably most importantly), I don't have control over the installed version of Houdini on any of our render farm's server blades here at the University. We have a decent number of shots, so being able to render on the farm will be helpful in rendering the remainder of the film in a reasonable amount of time.

Since the flowfield solution is probably not the best option (given the above reasons), I am trying to figure out how the scattered guides created in the Fur HDA are recognized as legitimate hair guides so I can force the HDA to view the the scattered Maya hair guides as legitimate. I guess my new modified question is if anyone knows what is special about the hair guides that are scattered using a Fur SOP (which is how the scattered guides are generated in the Fur HDA in H11) that allows the Fur procedural shader to recognize them as legit hair guides to drive hair generation?

Edited August 19, 2011 by Mister Fidget

[Mister Fidget]

Good news everyone! I figured it out how to drive hair using imported guide curves without using the flowfield SOP! The flowfield SOP is a good solution for individual artists working on a project in isolation, but if someone has to share their work on a collaborative project then using an experimental node like flowfield can create a sticky situation (like for instance, my situation that I explained in the last post).

I am including an image of the hair as driven by only the imported guide hairs. I still need to work out some problems that are causing the procedurally generated hairs to not shape quite right (as is probably obvious from the image), but at least the main hurdle of getting the foreign guide hairs recognized properly has been overcome.

You are right jim c: there seems to be very little out there on the topic of grooming long hair in Houdini. There seems to be just as little about successfully importing guide curves from outside applications. If either one was easier/more documented I think that a lot more hair would be done in Houdini. Thus, I will post the file once I have cleaned it up some so that others can dissect the process I went through. I'll also explain the concepts of what I did for the learning and benefit of others. Thanks again jim; I could not have figured it out without your instructions and example file.

[michael]

sorry this took so long

please find attached a very simple hip file with a nice VOP SOP that SESI sent me way back...

it will maintain the length of a curve (~99.9% anyway)

maintain_length_vop_example.hip

[dobin]

that's a very good example but even though it's not very easy to animate long hair in Houdini. Thats why i've suggested to use animated guides from Maya...ability to use start curve attract and siffness there come very handy when you want to maintain the shape of the animated hair.

Here is an example how to use splines from Maya as hair guides in Houdini:

hair_external_guides.hip

[jim c]

Michael, thanks for posting that!

Is this only for H11? Because when I open it in H10 I get errors and warning about various missing components.

[michael]

hmmm...

not sure - I can't think of anything in the file that would be just in 11 and not 10....

the only important part is the VOP - the rest is just a demo of what it does...

[Owl]

importing curves and animated meshes from 3d party is sort of simple after you figure some things out (had same problems and got a lot of help at odforce).

I've modified dobins file as an example(rebuilt the skin mesh to show that it then matches/sorts curves according to skin mesh). You can import iges curves and skin(animated).

hair_external_guides_2.hip

[abvfx]

It would be great if you could import zbrush Fibermesh and convert the polys into guide curves. I tried with the same method of converting blenders guides into curves but it didnt work .

edit: I figured a way.

Edited February 3, 2012 by phrenzy84

[Sifis]

I figured a way.

Hey phrenzy84, can you share your method? A Hip file maybe?

[webbyeasy]

sorry for reopening an old thread, I'm on H15 and importing guide curves via Almebic and it works fine, but I can't find anything documentation on using animated guides.

 

I've spent a bit of time diving around in the new fur setup and there appears to be a timeshift / framehold for the imported groom. When I bypass that things start to break, 

 

How do I hook in my animated curves into the fur system? I've tried manually pointing the object merge on the dynamic guide to the curves but that doesnt work at all.

 

thanks everyone.