Chrome Material

[nboy22]

i would like to make a Clean and nice Reflective Chrome. like on hub caps on cars. I'm a bit stumped on how to achieve this affect and i would preferably want to use a Blinn for it. Could anyone tell me the settings to complete this affect?

[joojaa]

go to www.pixho.com for good starting points. Get the metal presets.

[nboy22]

yes.. i've seen that before, i've gotten the silver shader, but you must do a whole bunch of other stuff just to achieve that look.. because it is done with a ansiotropic material or whatever.. what i'm talking about is making a blinn, because those ansiotropic ones you need to do environment mapping and all this other stuff, you can't just throw lights on it and make it look good .. i'm only a beginner pretty much

[bmcaff]

Aaah, we all wish it was as simple as throwing lights on it to make it look good. Unfortunately the nature of chrome means that lights don't do much good. By this I mean it has no (or little) diffuse component to be affected by lights. Chrome acts just like a mirror and is defined by its environment.
To answer you question chrome can be acheived very easily by using a very simple blinn shader.( There should be some examples oon the Alias website)
Set the colour and/or the diffuse to black/zero.
Set reflectivity to 1 and have a high spec rolloff and low eccentricity with 100% white specular colour. Put a simple spherical environment map in the reflected colour channel and use an image as texture map or for really simple studio chrome try a black and white gradient ramp (works better to have a black horizon line in the center fading to white at the bottom... experiment here).
It also helps (but is not necessary) to raytrace so it reflects the model
Chrome obviously is most effective on curved or organic surfaces and rarely looks good on flat planes, don't forget to have nice radii on all your edges.

[nboy22]

thanks.. that's more of what i wanted. but i'm still confused on what an environment map is, i know what a ramp shader is.. but not environment map, do you have any tutorials on environment maps?

[joojaa]

You can quite easily just turn the pixhos verison to a phong shader (sharper highlight more closer to what the chrome should have) from the doopdown menu. And start working from that.

Environment map, is a way to simulate a reflective environment. Its cheap and usualy quite effective at comveying the fact that this is a reflective material. You could think of it as a big sphere (well its shape depends on how its wrapped it can also be a cube of pictures) surrounding the object. Except it works without raytracing, or in conjunction as follows. If you happen to raytrace then the reflection map acts as the color of the surronding whan the ray misses everything.

It is a cheap means to make convincing reflections without modelling a interesting environment to reflect.

[nboy22]

so on this ramp shader i would just use a Black to White color Ramp for the chrome? cause that would seem most logical

[bmcaff]

It depends on the look your after. Like I said, if you want a pure & simple studio chrome then a simple black & white gradient (horizon in middle) would work. For the classic dessert chrome (you see this in alot of 50's american car renderings) then make a ramp with a blue to white grad in the top half and a dark brown to sandy yellow in the bottom half (horizon line where the white and brown meet). There is no hard and fast rule and you should experiment with different ramps and colours 'til you get what you want.

The look you get from using ramps is not so realistic as using an image map but sometimes it gives a nicer result, especially for cars or products. Most high quality photos of cars and products for marketing and magazines are shot in a studio and have simple reflections. The reason is that it helps communicate the form of the object more effectively. The key to acheiving any material in 3D is observation of the real world material. You should also try to find some basic shading and lighting tutorials.. try http://www.learning-maya.com/

[nboy22]

Do you think one of you guys could make an Example and zip it up and send it to me at b_clark_22@hotmail.com ?? .. I'm still having alot of trouble getting this to work.. I can't quite get it to look like chrome, it's too black.

[bmcaff]

Here is the sample image (emailed the wire file)

http://www.bmcaff.com/post/studiochrome.jpg

This is the most basic chrome as I described above.