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View Full Version : Tire WIP - Help Adding more "Realism" Needed!


JellyFire
11-20-2006, 12:08 AM
I am in the mid stages of making a car for a short animation I'm doing, so today I got the wheel done. I feel that it's a bit on the week side, it doesn't help much that it's an old style tire that looks a bit cartoony in the first place. But I would like to add more "Realism" to it.

I'm by no means new to 3D or Maya, but I have only just started learning rendering techniques properly over the last few days! I'm progressing (what I persieve to be) quickly, but need a bit of a push in the right direction on this one.

Ok, so the tire with the big round chrome hubCap is my attempt, I still have to apply a little bump to the side of the rubber, but I want to work on it alot more. It seems rubberish, but more like a brand new tire straight out of the show room. The second image is of a tire I saw floating around in the 3DSMax forum, It has a really nice "feel" to it, I would like to aim for a render of that standard on the rubber. It has a kinda dusty look, like it's been rolling around on concrete and got a bit Chalky...

Hope you Render Guys have an idea how to achieve this, I want to be bleeding pixels at the end of the week!!! Really push myself at getting some nice results.
Thanks for any advice!
JellyFire

faultymoose
11-20-2006, 12:31 AM
The quality of lighting might be your biggest problem here. Remembering that specular highlights are in fact reflections of real world light sources (bright surfaces, the sky, the sun, lightbulbs, etc.)

Shader specular in Maya seeks to simulate these reflections with the use of a fairly generic highlight. It can be great for quick tests, but if you're really pushing for realism, you will at the very least need to break up the specular channel with a greyscale map. I'd probably soften that highlight quite a lot, add some more lights to your test scene (try GI Joe or something to help even the overall scene illumination).

The ultimate in realism would be to turn off specular all together and create an environment (could be as simple as some very bright white planes) for the tire to reflect. Give it a low reflectivity and a huge degree of blur. Of course, this will up your render times dramatically, and in all honesty would be unecessary overkill in most cases. You should be able to achieve a realistically reflective material by playing with specular channels and mapping the specular colour so it's a little 'dirtier'.

Also, obeying the fresnel effect is a great way to instantly improve the realism of a surface.

JellyFire
11-20-2006, 12:39 AM
There is a quick HDRI dome in there for test purposes, I've decided to keep on modelling with the car and work of the quality once it's all in the scene. I believe most of it will be hidden by body work and Shadows.

I will check out GI Joe, I've seen it's name mentioned a few times. Also what do you think of applying shaders to lights? I watched a tutorial where the guy added a light shader called phisical light I think. (I'm in MR of course)

Could you expand on the fresnel effect and tell me why it would add more realism?
Thanks for your reply ;)
JellyFire

faultymoose
11-20-2006, 12:47 AM
GI Joe is just a quick and easy solution to provide a decent AO effect from within Maya software, using a dome of lights.

The fresnel effect (the 's' is silent) describes the way in which a surface becomes more reflective and less transparent at glancing angles.

So for example, a glass bottle will be significantly more reflective and less transparent along the edges (those faces that are perpendicular to the camera's aim vector) than across the 'front' faces.

Every object in real life exhibits this to some degree. Even diffuse surfaces such as skin and paper. I'm a little OCD about it, but I set up a basic fresnel network on every single shader I create. Sometimes the effect is extremely subtle (only 5 percent difference between facing versus glancing angles, for example) and sometimes it's almost the full range of 1% - 100%

To do so, plug a Sampling Info node's 'facing ratio' attribute into a ramp shader's v-coord, set the ramp to a simple black > white gradient, then plug the ramp into the object's reflection/specularity channels. You can now adjust the values of the ramp's high and low colors to adjust the degree of falloff.

As another general tip, I usually set the diffuse to the inverse of the reflectivity (ie. if reflectivity is ramped from 0.2 > 0.4, then diffuse will be ramped from 0.8 > 0.6). This is just a guideline, but it might help.

acidream
11-20-2006, 09:41 AM
One thing I have done in the past for dark rubbery type surfaces is to make a 3d cloud and turn off the "soft edges" checkbox and make both color 1 and 2 black, then bring color 2 up just a tad so it's a dark grey, and put this to the color attribute. It breaks up the solid black color just a tad bit, I think it helps the realism. Depending on how chalky you want the tire, you can increase the colors up from black a bit. I think you can see something similar to this in the tire on the right.

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11-20-2006, 09:41 AM
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