Metal Surfaces

Metal, generic, non-raytraced - a quickly rendered, matt, generic metal
Metal, steel, raytraced - highly reflective, polished steel
Metal, aluminium, raytraced - blurry, reflective aluminium
Metal, rusty / weathered - rusty, scratched metal

Metal, generic, non-raytraced

This material is nice for a quick and easily rendered metal look to smaller or unimportant objects

I did not use the Metal or Strauss shaders but rather the Oren-Nayer-Blinn (ONB) because I wanted a better control over highlights.

Basically it's all just about decreasing Glossiness to 0-10 and upping the Specular to 75 and up on a very dark material (here grey 128). This results in very broad but shiny highlights with a quick falloff to deep, dark shadow areas.
To vary the structure, I also used a scratchy texturemap in the Specular slot.

Just by changing Diffuse color and specularitites you should be able to create a wide range of metals.

The included scratchmap is a low-res version of the one I use and is also included in the matlib

download matlib (68kb)

Metal, steel, raytraced

I often see newbies asking how to make chrome or other reflective metals. Rather than give the same answer every time, I decided to put up this tutorial.

I used the Blinn shader rather than Metal on a raytrace material because I like the better control over highlights. A black or very dark blue in the Diffuse channel will prevent the metal from looking washed-out and dull.
Specular Level is shot up to way above 100 (378 here) and Glossiness to around 50, resulting in sharp and bright highlights.

I used a mask with falloff in the Reflect channel to have the metal reflect more with increasing perpendicularity to the viewer. This is a real-life phenomenon that occures to any shiny surface; a ceramic coffee mug will actually reflect along the sides perpendiular to you. (in fact almost any surface will change its look depending on the angle it's seen from). For chrome, add full Reflect. Silver has a slightly lighter Diffuse color and is less reflective than chrome.

Most importantly though is the surrounding area of the metal. If you use a reflective material, you will of course need something to reflect! This is the actual secret behind chrome, silver or steel. Not the material itself, but its environment.

I usually use an environment map for general reflections and add in boxes or cylinders of black and white for specific accents. Placing these objects is a matter of trial-and-error and loads of testrenders as it's not possible to see it in realtime.
A trick is to place a lightsource in the scene and then use Place Highlight (Align rollout) on your reflective object. Then you put your black or white objects where the light ends up.

To speed up raytracing I strongly recommend everyone to use Blur's RayFX raytrace and shadow plugins. The image above shows lines in the reflections which is a known bug in the version I used, but it only occures sometimes.

I added a small scene without lightsources as an example for environmental reflections

download matlib (5kb)
download scene - R3.x (27kb)
get RayFX

Metal, aluminium, raytraced

I used the Oren-Nayer-Blinn (ONB) shader rather than Metal on a raytrace material because I like the better control over highlights. ONB also gave it a softer look.

A light grey in Diffuse is fine for aluminium as it will lighten up and wash out the reflections.

Specular Level is shot up to 190 and Glossiness way down to 0-5, resulting in broad but bright highlights.

Using a mask with falloff in the Reflect channel to have the metal reflect more with increasing perpendicularity to the viewer would add realism, but isn't that necessary since it will be blurred anyway.

In the Raytracer Controls rollout I used the Multiresolution Adaptive Antialiaser and upped its Blur/Defocus to 2 (Offset), 4 (Aspect), 0,5 (Defocus) and 1 (DF aspect).

As with all reflective materials, the surrounding area is most important. If you use a reflective material, you will of course need something to reflect!

I usually use an environment map for general reflections and add in boxes or cylinders of black and white for specific accents. Placing these objects is a matter of trial-and-error and loads of testrenders as it's not possible to see it in realtime.
A trick is to place a lightsource in the scene and then use Place Highlight (Align rollout) on your reflective object. Then you put your black or white objects where the light ends up.

To speed up raytracing I strongly recommend everyone to use Blur's RayFX raytrace and shadow plugins.

The included scratchmap is a low-res version of the one I use and also included in the matlib.

I also added a small scene without lightsources as an example for environmental reflections.

download matlib (68kb)
download scene - R3.x (27kb)
get RayFX

Metal, rusty / weathered

Corroding metal is no big trick. The most important thing is to use your Diffuse textures or procedurals in the specularity slots as well, since the shinyness has to vary over the surface. I often use the very same textures in Diffuse, specularities and Bump and just darken, lighten or contrast them more using Color Correct in MAX.

I used two materials here, one overall, tileable, rusty map and one for clean metal. I then mixed these together using a scratchy texture. It's a good thing to mix tileable maps with others using noise-, smoke-, dirt- or other procedurals or texturemaps. This will prevent repeated patterns and give the surface a varied appearance.

Having different maps for rust, metal, dirt and other weathered effects and then mix them together using masks will ease corrections later.

The maps below are low-res versions of the rust- and scratchmap I use and are also included in the matlib

d_scratchmask_tn.jpeg

d_scratchmask_tn.jpeg

download matlib (56kb)
get Color Correct

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