'Texturing & Lighting'


'Brief Consideration About Materials'

by Pedro Toledo
 



Software Used :



Generic 3d Packages, 3dsmax, maya, cinema4d, xsi, zbrush, lightwave etc

Introduction :



I originally made this tutorial for a lecture I gave at CCAA, a school in Brazil where I help to run the Post-Graduation course in Game Art. It came from the need to explain some elements of the materials that are commonly misunderstood. Especially about Specular maps which, sometimes, seem to be a bit confusing for some people.

Most artists, in general, have a pretty good understanding of Diffuse, Normal and Alpha maps, but it's often on the Specular map that they will get lost and sometimes even ruin a pretty good asset.

I hope you enjoy this tutorial.


Textures & Shaders :



If the shape of an object, in 3D, is the result of its geometry, the material from which this object is made of is the result of its shader and textures. Shaders are instructions that tell the render how an object should be displayed. Textures are images that provide visual information to the shader. They can be extracted from real life photographs, they can be digital paintings, or even procedurally generated (Fig.01).


Fig.01

In this way, we use textures as inputs of a shader, defining attributes such as color, reflectivity, transparency, roughness, brightness and other characteristics of a possible material. Out of these textures, the most common are:

  • Diffuse
  • Specular (and Specular Power - aka Glossiness)
  • Normals
  • Alpha
  • Self-Illumination

Normals Maps will change the normals of a given surface. They will make the light bounce off the surface as if it had hit something other than just the polygons.

Alpha Maps define transparency. It can be on materials such as water, glass, fire, smoke... Or it can also be used for creating different silhouettes, gaps and rips on simple surfaces (Fig.02).


Fig.02



Cedric_Seaut_Character_Modeling


So, in some ways, if we disregard the truly transparent or translucent materials, like glass, where the transparency is at the core nature of the material, it would be ok to say that Alpha and Normal maps alter how we see the shape of an object more than the material itself.

Self-Illumination or Glow only defines parts of the object that emits light; that glow in the dark (Fig.03). Thus, transparency, embossing and brightness are material characteristics conferred by the respective use of the following maps: Alpha, Normals and Self-Illumination.


Fig.03

But what about all the other aspects? Those that really define the nature of a material. Is it light or dark? Smooth or rough? Clean or dirty? Reflective or matte? It is made of metal, clay, wood or plastic? Is it wet or dry? Rusty? Stained? Scratched? Old and worn, or brand new? All these variables, and many more, are controlled by two maps: Diffuse and Specular (well, maybe three maps, since there's still the Specular Power. But because this one only affects the specularity, I'll consider it as part of the Specular slot).

But what are they? Everyone who works with 3D has at least a basic understanding that Diffuse is the color of an object and Specular is the light reflected on its surface... the highlights. But this definition is somewhat simplistic. We must remember that everything we see around us in the world is only visible because they are reflecting light. In essence, everything we see, if it doesn't emit light, reflects light (Fig.04).


Fig.04

As in this example, the light-bulb will emit light in all directions and some of these rays will hit the teapot. The teapot will absorb part of the rays, in this case mostly the blues and greens, and bounce off the reds. Some of these bounced rays will pass through our pupils hitting our retinas, and this information will be sent to our brain so we can finally "see" the teapot.

The thing is, there are two ways this reflection may happen:

Diffuse reflection is a type of reflection where the light is reflected from the surface
at multiple different angles (Fig.05).


Fig.05

Page 1

Related Tutorials


If you liked reading this tutorial, you may also be interested in the following.

"Fast Ambient Occlusion in 3ds Max" by Tom Isaksen
Ambient occlusion adds great realism to your renders, but can be bit cumbersome to set up in Max, particular
if you’re using a mix of mental ray shaders and standard shaders. You could create an ambient occlusion effect
by using lights, but it can be slow to render and tricky to get the right look.



"VRay for Maya Demo" by Dennis Holmboe
My name is Dennis and I just got my hands on the “VRay For Maya” demo! A friend asked if I could explain the
basics, so here is a very simple tutorial.

Your rating:  
  Rating: 4.75, Votes: 85 
Tairo on Thu, 18 November 2010 7:05pm

Very cool tutorial, i was at the original lecture in CCAA, it was very interting. one of Brazilians best 3D Artists there is.
Graham on Thu, 18 November 2010 11:32pm

Simple and concise break down of the science of specularity Pedro! I have been studying 3d for a few years now, and I have been struggling to understand how to properly use color in my specular maps. This tutorial has finally cleared up many of the misconceptions I`ve encountered and has given me a more solid understanding of how specular reflections work in reality. I thank you so much!
Thrillhouse900 (Forums) on Fri, 19 November 2010 3:10pm

Unreal tutorial, such valuable information!Thank you!!
Mr.T on Fri, 19 November 2010 3:53pm

Amazing tutorial, thanks for your time.
Hynol on Fri, 19 November 2010 9:12pm

As I understand, velvet is conductor? ;) Also I don't quite understand why you are using color map for specular highlights in dielectric - it is mistake - using desaturated image is correct method.
Usman on Fri, 19 November 2010 10:45pm

WOW really I dont have words to thank you for this really really awesome.
Matifou on Sat, 20 November 2010 9:52pm

Great tutorial!
Thank you!
Muˇrcio Siviero on Thu, 25 November 2010 11:20am

Congratulations!!!

Very nice!!!
Ricardo Duarte on Thu, 25 November 2010 6:08pm

Great work!!! Congratulations...from Brasil! (with S!)
St on Fri, 26 November 2010 7:17pm

Informative! Thanks for sharing.
Wayne on Mon, 06 December 2010 11:52am

Thanks a loooooot!!really useful for me!!
Meysam on Tue, 14 December 2010 11:19am

so good dude . scientific and easy to understand . thank you .
Vitaly on Mon, 16 May 2011 1:50pm

Thank you very much, Pedro!
The marvellous info.
Waiting for new tutorials!
Rees on Fri, 25 November 2011 12:51pm

Quite valuable tip I would say, not sure how that gonna translate into the reflection mapping, I don't use specular mapping anymore hehe, will test it & see.
Raja Haroon on Mon, 02 January 2012 6:40am

Great Information, i think you have to make a video Tutorials about that.
Nana Ofosu-Osei on Thu, 26 April 2012 1:12pm

Thank you so much fro this excellent Tutorial. I understand so much more now.
Issac on Fri, 17 August 2012 3:40pm

Thank you very much.
Simple and Super.
Very Informative .
Samtherocker on Fri, 04 January 2013 6:27pm

Thanks for sharing this helpful information with us...You are the master!!
Nilupul Perera on Sat, 23 November 2013 4:38am

It is very useful. I am 3d loving Neurologist in Sri Lanka. Hope to see more articles from you.
Thank you soooooo much.
Cr@chrisrush.net on Thu, 03 April 2014 12:11pm

img 22 is missing

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