Practice 0: Intro to Maya/Arnold First Class

CS22/122 Loeb

In this class we use Maya to build the object and determine it's shape and then we use a built in software package called Arnold to add materials to that object.

Arnold uses software to recreate the physical world.

When you look at an object, we see it because there is light in the environment. We can learn about the object by the way the light bounces off that object.

This exercise will let you play a bit with the materials we put onto objects in order to see how cool Arnold is and get a feel for the process.

The first thing you notice when you look at an object is usually the color.

You might notice the reflections

Or the highlights that make an object look shiny (caused by refractions)

And the light might go through the object, making it look transparent or translucent

Let's play around and see how that works!

Go to the Files to Download For Class Folder

If you are ever looking for the Files to Download for Class Folder, it is linked from the class website menu or HERE.

  • Download the entire first class folder

While it is zipping and downloading....

*It is extremely important to set up your project every time you start working on Maya. You first set up the new project, and later you just make sure you are working within that project, in the correct directory structure.

It is very tempting to get lazy and just work on the desktop. THAT IS A MISTAKE! You won't feel it at first, but as you continue working and your scenes get more complex, the problems will start to escalate and you will regret taking shortcuts.*

To reiterate---Every time you work in Maya, you need to set up your project or make sure you are in the correct project.

Start a new project.

Go to File>Project Window.

Click on New in the upper right corner.

Create a project called yourName_Practice

In this course will make a separate project for each of the assignments plus one for the practice sheets and the in-class exercises.

Right now, create one for the practice sheets and in-class workshops.

and click "Accept" to accept the default folders in your project.

To make Maya projects easier to find in the future

  • Open the Finder on your Mac.
  • In the Documents Folder go to Maya>projects
  • Drag the projects folder to the sidebar of the Finder under Favorites as shown above.

  • You want to drag it so that a line shows in the sidebar creating space for this new folder. Don't add the projects to another folder!

This creates a shortcut for finding your project folder.

Double click on the zip file when it is downloaded.

  • In the first class folder, you will find
    • A file named first Class Arnold.ma
    • dreifaltigkeitsberg_2k.exr

Drag "first class arnold" file into the scenes folder for the Practice project.

Drag the exr image into the sourceimages folder for the Practice project.

It is critical that you work with your files organized correctly or you will run into problems with texturing and rendering. Never use a project directly off the desktop. Work from the projects folder located in the documents folder (and in your favorites panel on your finder)

You can open the file in two ways.

  • Double click on the file name in your finder (or right click and choose Maya2022.3)
  • Open Maya 2022.3 and choose "open"

The project folder opens. Choose the scene you are looking for, in this case, "first class arnold"

Your view panel should show the perspective viewport as below

If you don't see the background, hit the "6" key for texture view.

Next, make sure you are working in the Modeling - Standard Workspace

Here is what your are looking at in this scene:

  • five polgon spheres on polygon bases

  • a checkered table cloth
  • an Arnold skydome Light

Check it out: Zoom out (use the scroll wheel on your mouse) and you will see that the scene is inside a large sphere, called an Arnold SkyDome Light This dome casts a white light inward.

Scroll back in so the scene is as it was or use a trick by hitting the"open bracket key" [ which moves through the camera views you have used since your last save. You may need to click off the sphere and into the viewport to have this work.

Another navigation trick is to select an object, say one of the spheres, and hit the "f" key to frame in on that object.

The "a" key frames all the objects in the scene, which takes you too far out for this particular scene because all objects includes the sky dome, but it is worth trying.

The Outliner Window

Open the Outliner if it isn't open, by clicking on the name on the left of the UI. (if it isn't showing go to Windows>Outliner to open it). This is a very useful window to use.

I created a group called all_RenderBalls. Click on the plus signs by the group name and it opens up the objects in the group.

Anytime you see a + sign by a name in the Outliner, it means there are more objects or nodes parented to that object or group. You can keep clicking on the + signs until you see all the individual objects in this scene.

aiSurfaceShader

  • Select the left-most sphere and hit "f" to frame up on it.
  • Hit the "3" key to smooth the object in the viewer.
  • Select the base and shift select the sphere as shown above.
  • Objects that are selected are white. The last selected object is green.

Our goal is to assign new materials (shaders) to the spheres and bases to play around with what Arnold (our rendering software) can do.

By default, when you create an object it has a flat shader (no highlights) called a lambert. We want a material (I will use the term material and shader interchangeably) that has more interest.

Try rendering as it is. You can go to the Arnold tab and hit the render icon, or go to Arnold>Render

You will notice the checkerboard is actually green and white and the render ball is a flat gray color.

Adding new materials

To change the flat gray to give it color, or make it shiny, reflective, or transparent, we need to assign a new material to the object. The material on there now is Lambert1. We never change that in any way as that is the default for any object you create.

Assign a new material to the object.

  • RMB click on the sphere/base and go to Assign New Material

  • This opens a new window.
  • Choose Arnold>Shader
  • Choose aiStandardSurface

This replaces the default shader with the aiStandardSurface shader on all selected objects. In this case, the sphere and base. Both objects now have the same shader, so if you change the shader settings on one, it changes it for the other.

You will see in the render window that the sphere and base are now a shiny white.

  • Open the Attribute Window for the aiStandardSurface node
  • Change the name to M_base or M_baseColor

  • Under Base, change the color by clicking in the color box and selecting any color you'd like.

You will notice that the ViewPort window updates with the new color, and the color is on both the sphere and the base as would be expected. And the render changes color as well.

  • Make the weight 1.0 (100%) (In Maya 2022 it is automatically 1.0 but in earlier versions it defaults to .8)
  • Deslect the sphere and base to see how it looks.

The nice thing about the Arnold Render IPR window is that it updates as you move around in the Viewport.

You will also notice that the sphere and base are pretty shiny, they have a lot of specular highlights. Let's make it a flat color.

  • Turn the Specular weight down to 0

See the difference in render view?

  • Diffuse Roughness (under color in the Attribute Editor) spreads the color around a bit so it has a bit more, well, roughness. You can play with that a bit to see the difference.

  • Next in the Attribute Editor is Metalness. Metalness makes the color more metal-like. It can be confused with reflection, but they are different in that this isn't adjusting the reflection, it is adjusting the quality of the base color itself. Still, it makes the material quite shiny and reflective.

  • Try turning up Metalness

This makes it look like polished metal or a Christmas tree ornament.

The Diffuse Roughness is at 0 and grayed out when the Metalness is at 1.0. You can play around with decreasing the Metalness attribute value and increasing roughness. This makes it more of a matte metal finish.

This is a good time to SAVE!!! Hit Command + s

A good rule of thumb is to either have Auto Save on, or to just remember to save often, particularly if you've done enough work that it would be painful to lose it!

Using aiStandardSurface Shader and the Specularity Settings

Select ShadingSphere1 group (sphere and base) and assign a new material. Again, choose Arnold>Shader>aiStandardSurface. In the attribute editor, rename this material to M_specularity

aiStandardSurface is super flexible and can act much like a large number of materials, from wax to chrome, to glass. I will go into more detail on how shaders work, refraction, reflection, and transmission soon, but for now, let's just play. Specularity, simply put, is the way light bounces off an object's surface material.

  • Turn all the attribute value settings in the Base section of the material Attribute Editor to "0".
  • The object has no base color now.
  • It only has specular attributes.
  • Let's adjust those to see what happens.

The sphere is black and has specular highlights.

  • Start by reducing the Specular Weight.

  • At it looks like a flat black sphere.

  • Put the weight back to 1.0

  • Try changing the color of the specular highlight to something bright like yellow.

You may start noticing that the highlights are more yellow, especially around ridges along the base. If you can't see it, try turning the view in the ViewPort

The reflections you see are not based on the color but are strictly influenced by the specular algorithms in the shader material. In real life, we can't separate out shading attributes like this, so it can be a bit confusing.

Roughness in specularity is at .1 by default (10%). The rougher it is the more it looks like a matte finish, and at a specular roughness of 1.0 it is practically flat.

IOR stands for the Index of Refraction or Fresnel effect. A Fresnel lens focuses the light so it is seen differently from different sides. You can see this in a window. From straight on you only see out the window but from the side you often just see the reflection of the room. IOR is based on real life materials and you can find the actual IOR for various materials online at sites such as this.

Anisotropy makes the specualrity into bands like a CD that has ridges. You can play with that. Rotation, rotates the direction of the "ridges".

Play around with changing both the color, the metalness, and the specular highlight color to see what sorts of things you can create.

Transmission

Transmission is light that passes through an object, making it look translucent or transparent.

Assign a new material (aiStandardSurface) to the next sphere and base.

  • Rename the material to M_transmission

Leave everything at the standard settings and go to the Transmission Tab.

  • Change the Weight to make it a bigger number, even to 1.0 (100%)

It becomes clear but it looks funky.

In Arnold, in order for a transparent object to render well, you need to change another setting on the object itself.

In the Attribute Editor for the object gemoetry, to into the sphere shap and the Arnold Tab.

Uncheck Opaque

You need to turn off opaque for every object that you want to have transmission.

You can play a bit with the scatter, depth and anisotropy if you'd like to see how those work.

Presets

Arnold has some preset settings to help you simulate various materials in one easy step. Let's try it.

  • Assign a new material to the next sphere and base to the right.

  • Name it M_presets

To the right of the name is a Presets Tab. Select it, choose a material from the drop down list and replace. See what happens.

Very cool stuff, eh?