Kristinka Hair Tests

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rray
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Re: Kristinka Hair Tests

Post by rray » 14 Mar 2010, 21:58

RayKrH20.jpg
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scaron
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Re: Kristinka Hair Tests

Post by scaron » 15 Mar 2010, 01:50

these are amazing... keep em coming!

izze
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Re: Kristinka Hair Tests

Post by izze » 16 Mar 2010, 17:45

Hey rray, can you please share more information about linking the strand size to camera distance? How to go about that? The hair I have looks great until I pull the camera back, then it gets thicker. Thanks!

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Re: Kristinka Hair Tests

Post by miga » 16 Mar 2010, 19:46

rray wrote:Experimenting with weight maps--
Image
That one looks really nice!

edit: Oh, quoting images doesn't work; I'm talking about the curly short black hair

Moderator edit: go to the image properties, copy the image url & place it inbetween [img] tags... - HB

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rray
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Re: Kristinka Hair Tests

Post by rray » 16 Mar 2010, 22:37

Thanks Steven, I will continue the spamming^^

izze, I've never done this but try something like this.
The hair will have to get thinner when it's further away from the camera. There's usually a ^2 somewhere in the equation when it comes to distance/size relationship but I don't know the exact math.
I would try 1/(ctr_dist_cam(emitter_nurbs)^2) as a factor for the hair thickness.
Also if you intend to modify the camera's fov, I would work this in as a factor as well.
So unless there's something fundementally wrong with my maths here (probably is :ymblushing: ) you would set something like 1/(ctr_dist_cam(emitter_nurbs)^2) * (1/Camera.camera.fov) * 5 as the expression for "size" in kH_Emit_Guides (try different values for the "5" depending on the hair thickness you want)

miga, thanks!
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izze
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Re: Kristinka Hair Tests

Post by izze » 17 Mar 2010, 17:35

Thanks for the info. Great tests!

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rray
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Re: Kristinka Hair Tests

Post by rray » 17 Mar 2010, 20:38

Btw: I just read on the Softimage mailing list, the pixel size unit thing was changed in 2011.
*-:) *-:)
RayKrH22.jpg
lit by devebec's building.hdr. The optimize compound helps a lot fitting all those hair into 2 GB RAM
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Ahmidou
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Re: Kristinka Hair Tests

Post by Ahmidou » 18 Mar 2010, 12:06

yes, it's working now ;)

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Hirazi Blue
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Re: Kristinka Hair Tests

Post by Hirazi Blue » 18 Mar 2010, 12:11

@rray - Tutorial? :ympray: :D
...

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rray
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Re: Kristinka Hair Tests

Post by rray » 19 Mar 2010, 23:54

~o) There is something in the making

Don't want to promis too much :^o could take a bit
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druitre
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Re: Kristinka Hair Tests

Post by druitre » 20 Mar 2010, 16:27

Btw: I just read on the Softimage mailing list, the pixel size unit thing was changed in 2011.
What will (all of) the consequences of that change be? From this thread I understand at the moment there's a problem when rendering animations with K-hair (the hair thickness doesn't stay constant relative to world space), right? Is it a MR issue or something else?

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Mathaeus
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Re: Kristinka Hair Tests

Post by Mathaeus » 20 Mar 2010, 16:39

It's Softimage issue, that can be fixed by adding a few nodes. Consequence is that hairs looks thinner with camera zoom and reverse, also, render region and final render can look different...

For animations, without some wild camera movements, I found the current option a bit better, to be honest. Seems to be much easier to get correct anti aliasing...
The renderer "turtle" used by this scene, is not currently available. The "turtle" renderer will be used instead.

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druitre
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Re: Kristinka Hair Tests

Post by druitre » 20 Mar 2010, 17:03

Hi Mathaeus,

sorry, I don't understand your answer. Do you say that after 'adding a few nodes', the hair won't 'look thinner with camera zoom'?

And when you say 'I found the current option a bit better', do you mean not using those 'few nodes' is better than using them or do you mean the difference between 2010 and 2011?

Also, with 'camera zoom', do you mean lens angle or camera distance?

I think a better way to put my initial question would be: what is that pixel size unit issue, what's it about and what problems will be gone with the fix?

thanks, Jasper

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Mathaeus
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Re: Kristinka Hair Tests

Post by Mathaeus » 20 Mar 2010, 19:28

druitre wrote:Hi Mathaeus,
I think a better way to put my initial question would be: what is that pixel size unit issue, what's it about and what problems will be gone with the fix?
thanks, Jasper
Actually, I would call that 'choice', more than 'issue'. Rendering a lot of thin, overlapping objects, that's always a challenge. Regardless of world or screen space, you'll have to 'do something' with, for example, thin grass which is far away from camera, that constantly 'buzzing' from frame to frame. At this stage, current, screen space, seems to be easier to control.

It's not big deal to create compound that changes strand size according to output resolution, distance to camera and camera angle, but this one can kill the playback. Also you still won't get it right in render region, unless you manually enter a some 'estimate' values.

Anyway, I'll try to create compound.
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Mathaeus
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Re: Kristinka Hair Tests

Post by Mathaeus » 20 Mar 2010, 20:56

Hi,

I think that is the formula in ICE language. "1024" is screen resolution (I think it's horizontal resolution), "0.1" is strand thickness in SI units. Probably it's good idea to ad "clamp" node at the end, for keeping strand size in desired screen units. This one uses point position ("strand root"). For more accurate, but slower calculation, strand position may be used instead.

Cheers

screen shot of ICE tree
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Ahmidou
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Re: Kristinka Hair Tests

Post by Ahmidou » 21 Mar 2010, 12:19

Actually, the pixel size unit limitation was not changed in 2011 but you'll now have the choice between screen space and world space size.

Hey Mathaeus I found some lecture for you :D
http://www.disneyanimation.com/library/ ... umHair.pdf

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