hairfx crazyness

[Ruairi]

Hey, I've just recently bought my own personal copy of Vray, so hello!

It's pretty damn cool, I have to say, but (and there's always a but) I've run into a couple of problems getting a character set up to render on a series of commercials I'm working on

I'm trying to get a character working with hairfx fur and rendered in vray. Since I can't use decent motion blur or depth of field with hairFX rendered hair, I'm attempting to render it as geometry, but keep getting this "object has changing topology, unable to motion blur" type error on the hair objects, so the surface they are emitting from is blurring fine, but the actual hairs themselves are fully sharp, which naturally look crap in a rendered sequence as the fur is getting "left behind" when the character moves quickly. any idea why it might *think* the topology is changing, when the vertex count of the base object is so obviously not?

anyone come across this before?

the other thing is, I'd like to simulate the look of anamorphic lenses, and there's no aspect ratio controls for defocusing (I've posted this in the wishlist area too)

cheers,
Ruairi Robinson

[egz]

Hi Ruairi,

I've had some problems with hairFX and motion blur when using geometry hair. The solution was to clone the hair emitter, and hide the original. That way the object generating the hairs isn't rendered. VRay or HairFX seems to have some problems when one object depends on another (hairs depend on their emitter in this case). As far as I can recall the problem was related to the order in which the objects are created internally in vray.

I second your lens aspect ratio wish

[Ruairi]

Hey Egz - I saw your post about this earlier, and attempted this - unfortunately the skin on this character goes nuts when you try and clone him, so I couldn't even get as far as testing it.

It seems like an odd thing to have to do as a workaround - besides, the scene file containing this character is already 100 odd megs in size with all the cloth sim crap and morph targets etc, that adding any more redundant detail just seems insane (There are going to be 3-4 characters like this in the scene at any given time)

Hi Ruairi,

I've had some problems with hairFX and motion blur when using geometry hair. The solution was to clone the hair emitter, and hide the original. That way the object generating the hairs isn't rendered. VRay or HairFX seems to have some problems when one object depends on another (hairs depend on their emitter in this case). As far as I can recall the problem was related to the order in which the objects are created internally in vray.

I second your lens aspect ratio wish

[egz]

Hey Egz - I saw your post about this earlier, and attempted this - unfortunately the skin on this character goes nuts when you try and clone him, so I couldn't even get as far as testing it.

It seems like an odd thing to have to do as a workaround - besides, the scene file containing this character is already 100 odd megs in size with all the cloth sim crap and morph targets etc, that adding any more redundant detail just seems insane (There are going to be 3-4 characters like this in the scene at any given time)

I agree, the workaround is undesireable when you have large scenes. Hopefully Vlado and Ivan (at DDAG) can figure it out. You should report the problem to DDAG/TutboSquid as well. The more people that report the problem, the more attention they will give it.

[Ruairi]

got a workaround from Vlado that seems to work perfectly:

- Unlink the hairfxView object from its emitter
- Apply a Linked XForm modifier to the hairfxView and attach it to the emitter
- Apply SimCloth



fixes the cloth dynamics thingy anyway!

[egz]

cool, good to know!

[Da_elf]

how good is hairFX compaired to shag hair? were there lots of improvements?

[Syclone1]

Glad you got it sorted out Ruairi...

-dave

[Ruairi]

cool, good to know!

Whooops - I had 2 problems, and I posted the fix for the OTHER one here.

Problem 1) - when using simcloth 3 to to dynamics, when the mesh moves too fast the hair is occasionally "left behind" like the frame substeps are not accurate enough (increasing the simcloth substeps made no difference - the solution for this is the one I already listed above. It's also a neater workaround than the one EGZ listed previously because you don't need redundant copies of geometry, which is painful on large scenes when you are trying to keep things as trim as possible.

Problem 2) geometry ain't motion blurring properly, because the vertex count is changing on the hair mesh. Apparently, middle strand randomization causes the vertex count to change, so setting this back to zero makes the hair mblur perfectly in Vray, result = joy!

apparently the way middle strand randomization works will be changed in hairfx 1.6 so that it preserves vertex count.

so now I can get geometry hair working with vray Depth of field and motion blur and GI and it all works fucking great, so thanks to Ivan and Vlado for sorting things out

I like HairFX a lot more now that it's working properly

The most frustrating part of it currently is the way you work with guide splines, you have to have each guide hair as a separate spline with a separate , non instanced model hair modifier on each hair, so to move a point on another hair you gotta keep going in and out of sub object modes on each - it would be great if you could just have them all as the one object, and be able to select and move multiple points on multiple guide splines at once. And the dynamics suck ass, but it seems to work pretty well with simcloth, so I guess that's ok

It also misses the kind of grooming tools that Ornatrix has, but seeing as I couldn't get the demo of Ornatrix to work for more than 5 minutes without crashing, I'm not sure I'd trust it in production just yet.

[egz]

The scene I had problems with didn't use SimCloth, and it only had short bristle in selected locations on a fairly low poly character. So in that case the duplicate geometry trick worked like a charm. I'll keep the linked xform workaround in mind for more complicated scenes in the future, unless they find a way to fix it first