Practice 0: Intro to Maya/Arnold First Class

CS22. Loeb W19

Let's have some fun. Go to the Files to Download For Class Folder

(in the Class Google Drive Folder) This is where you will find files for class and folders for turning in your homework.

Download the entire project folder, Called "lorie_practice" from the Google Drive.

  • 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.

This creates a shortcut for finding your project folder.

  • Drag the "lorie_practice" project directory/folder into the projects folder.

This puts the project you downloaded, plus all the files associated with it, into the proper directory on Maya.

*It is critical that you work with your files organized correctly or you will run into problems with texturing later on!


Within the lorie_practice project, you will find several sub-folders/directories (I'll use the term folder and directory interchangably - they are the same thing).

Open the Scenes Directory and double click on the Practice1_First Class Arnold.mb file to open it in Maya.

If you don't see the checkerboard on the plane, hit the 6 key on your keyboard to show textures.

Here is what your are looking at in this scene:

Scroll 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 that has an image of a field and some trees wrapped onto it. It is a High Dynamic Range Image (HDRI) that wraps correctly on the sphere and casts a light onto the objects that is projected through that image to make the objects seem like they belong in that scene.

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, but it is worth trying.

The Outliner Window (if it isn't showing go to Windows>Outliner to open it) shows all the objects in your scene. This is a very useful window to use.

I created a group called ShaderSpheres that has all the spheres and bases in it.

Nestled inside the group, are five ShadeingSpheres. Click on the plus sign next to those groups and you see the two objects that are in that group.

You can select and rename objects from the Outliner or by clicking on it in the ViewPort window. Shift click to select more than one object.

When an object is white it means it is selected. When it is green, it means it is the last selected object.

aiSurfaceShader

  • Select ShadingSphere (sphere and base) as shown above.
  • Let's assign a material to it.
  • I've already created a shader so we will use it for this sphere.
  • Right click on the sphere and base as shown
  • Assign Existing Material
  • Choose Shader1 from the dropdown list

  • Open the Attribute Window
  • Choose "shader1" tab
  • Under Base, change the color by clicking in the color box and selecting any color you'd like.
  • Make the weight 1.0 (100%) For some reason, the default is always .8 or 80%.
  • Deslect the sphere and base to see how it looks.

Let's do a render to see how it looks.

In the Arnold shelf, click the Render IPR button. It may take a moment to open.

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.

Let's make the base a different color. Select it. Right click on it, but this time, choose "Assign New Material"

The Assign New Material window opens. Under Arnold, choose Shader and then aiStandardSurface.

Repeat the steps above but choose aiStandardSurface4 tab in the Attribute Editor (or whatever number it is in your scene) and change that color, make it's weight 1.0.

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?