Hair render issue

[chipmasque]

It's kind of hard to visualize the problem you describe without seeing some images. Could you post some illustrative renders and maybe some screen shots of your particle system and hair material setup?

In answer to your question, in my experience frame-by-frame adjustments of static hair particles haven't been necessary, but that doesn't cover all possibilities by any means.

[orozimbo]

Sorry chip, it´s really hard to analise the situation without some reference. This images were render with the same setup but two diferent cameras. Note the hair has two very diferent look. The first image is a closeup, the second was render in a low resolution (almost DV) e the last one was render in HD and downsized to the same resolution.

Any suggestion?

[chipmasque]

I'm assuming that since you called these Static particles that you're using the 2.45 release rather than a development (SVN) build with the new hair system.

Looks to me like the static particles are being rendered as if the strands are essentiallly dimensionless in thickness, i.e. always 1 pixel. At distance, that would make for a thicker and more solid appearance than in closeups.

In your material specs, have you used the Strands parameter (Links & Pipeline tab) to set a beginning and ending dimension? If not, try that, it may help.

Also try using a Blend Texture to taper the opacity from root to tip, that can give some "shading dimension." Right now it looks as if the strands are a constant opacity. The Manual has some info about using this method.

Very nice character and setting, btw, very evocative use of shadows.

[Hunkadoodledoo]

It seems like I addressed this before here or on BlenderArtists...I never understood how the hair thickness settings were zoom and resolution independant. If you set your strand widths to 2 pixels start and 1 pixel end, it doesn't matter how far away or close the camera is - the strands with render 2 pixels wide at the base and 1 pixel wide at the tip. If you render your image at 800x600 and at 1600x1200, the larger image will appear to have thinner strands (even though they are still just 2 pixels wide at the base and 1 pixel wide at the tip). I just never understood that choice. Maybe it will change in 2.46.

I know that sometimes, having static strand render widths may be seen as a feature, but it seems like if you want strands that appear the same no matter how you render the image, you would make it scale dynamically with the camera distance and image dimensions.

Funny you should mention this...I began a hairball animation that will show this in action. Maybe I'll post tomorrow? I dunno. I have the flu....Frowny face.

[chipmasque]

You can set strand parameters in Blender units afaik. This should be a solution to the problem you describe, no?

[orozimbo]

wow! I´d really like to know about the improvements in peach project, but I choose use the last stabe version ´cause I don´t have a programer team to support me if any bugs pop up suddenly (I´m already behind my schedule). About the particle setup, I indeed made some ajustment´s in strands and in the opacity blend texture (in fact that was what I´m trying to do to compensate the inconsistent look).

Hunkadoodledoo, I´m glad to realiesed I´m not the only one with the problem. Please, let me see the result of your efforts.

By the way Chip, what you mean with "Blender units afaik"?

[chipmasque]

By the way Chip, what you mean with "Blender units afaik"?Apologies, I was mistaken about this. The current 2.45 release doesn't have the option for specifying strand dimensions in Blender units, the development SVN builds do. I've been experimenting with these lately, and thought it was an option for the earlier build as well.

The next release, 2.46, is slated for March/April btw, if your schedule can allow for the wait. Many new & improved features from what I've seen and read.

[Hunkadoodledoo]

The current 2.45 release doesn't have the option for specifying strand dimensions in Blender units, the development SVN builds do.

Good to know! I was rendering my hairball test at work, but I was put on bed rest for my illness, so I wasn't able to post it. Hopefully I can on Monday. Although, with the changes mentioned here, it almost seems unnecessary.

[chipmasque]

The new hair particles are still in development, and not completely without probs. I'm testing the "Blender untis" setting myself at the moment, not sure if it's doing what I expected. I've also had some strange issues with child-particle strands growing out of places they shouldn't. Not all smooth sailing yet, at least not for me.

EDIT_____

Here's some test renders, previews of what I assume will be in 2.46:
http://img182.imageshack.us/img182/3628/bustranddimsvl1.jpg

I'm using only parent strands to break up the contours of an otherwise all-mesh "wig" for my model. Scene scale is 1 Blender Unit (BU) = 1 cm, and the values in the images are in BU's. Model is built to life size at the scene scale, approx. 175 cm tall. The variable strand weight's a real boon, makes it possible to tailor the strands to the look of the bump-mapped hair mesh surface. The wig mesh is also a soft-body object, so I'll be testing the movement aspects of the strands with some overnight renders.

This was done with an SVN build from a while back, I had some problems with the most recent "Trunk" build, none of the mesh's image textures would show or be used if I had a particle emitter on the mesh. Ah, life on the bleedin' edge :D

[orozimbo]

Hey Chip, your model is gorgeous! But the exemplo doesn´t show the our problem. Yet, I believe you, by the description, when you tell me it can solve the problem and I indeed will postpone the render ´til the next stable version of blender.

Thank´s you two guys!

[chipmasque]

You're right, orozimbo, I'll see if I can post some comparative shots showing the appearance at different camera distances later on. Right now I'm stuggling with making the strands animate well, so it may be a while. But at least it shows that the strands are not just pixels-width-based, which is where your problems arises, I believe.

And thank you for your comment on the model :)

EDIT: Here's a comparison of near and far renditions of the same hair system

http://img152.imageshack.us/img152/7313/nearhairfarhairtj4.jpg

As you can see, she's beside herself with joy at getting a new 'do... ;)

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