September 13, 2022 Workshop 5 Notes

LIGHTING AND MATERIALS, MAYA SOFTWARE RENDERING OPTION

This workshop is developed after techniques described in the Robinson text,. it contains examples that are reinforced by background concepts in Chapters Chapter 14 + Chapter 15 (part), pages 349 402 

1. Shaders in Maya are based upon standard rendering algorithms and include the following types:  

• Lambert – flat – cosine shading (Lambert’s law)
• Phong – typical phong (spectral highlight)
• Phong E – spectral highlight in white
• Blinn – metallic objects
• Anistropic – good for material with grooves
• Layered Shader – more than one material
• Ramp Shader – ramp color (eye ball)
• Shadows …. Map of shadow lines from viewpoint of light sources (geo calculation)

These types of shaders are acessible through the hypershade dialog box or Window/Rendering Editors/Hypershade

2. Lighting types & 3 point lighting  - Chapter 14

Lighting types commonly used are 1) Ambient, 2) Distant/Directional, 3) Point and 4) Spot Light which appear from left to right in the Rendering Shelf tab in Maya. Ambient light provides general background illumination. A Distant/Directional light provides parallel light rays from a specific angular orientation, and may be used to mimic such distant lights as sunlight or moonlight. A point light is an omni-directional light that sends light out in all directions from a single location. A directional light sends light in a specific direction at a specific angle from a source location to a target location. 

Key and Fill Lighting: A typical three point lighting setup has a Spot light (also known as a Key light) to the upper right of model at full intensity to provide high contrast shadows, a Point light (also known as a fill light) to the upper left of the model at lower intensity filling in middle gray values, and a back spot light (also known as a back key light) at lower intensity than the front spot light and that provides some three-dimensional depth to the rendering.   

Key light set at full intenstity and positioned using the show manipulator tool (selected tool on left-hand side of Application window).

3. Materials Some Definition of Textures and Methods

Materials reference attribute nodes that determine look of an object. This includes

Texture – an material  that is mapped to object
      Types:  procedural (based on an algorithm) and
                    image (based on a photograph).

Bump Map – image read for its gray scale value that makes a material have the appearance of a surface relief

4. Menu items in Hypershade window (Left to Right)

From left to right the icons above the work area window (see above) have the following functions . Ignore for now those functions which are grayed out:

Clear Graph bar – clears out any nodes in work area
Add selected nodes to graph
Remove selected nodes from graph
Rearrange graph
Clear graph materials on selected objects
Hide attributes on selected nodes
Show connected attributes on selected nodes
Show primary attributes on selected nodes
Show attributes from custom attribute view
Toggle the display of attribute filter field
Toggle the icon swatch size
Turn on grid in graph window
Turn on gravity grid in graph windows

5. Basic material properties:

Color – RGB or HSV selection model color
Transparency – degree to which material is transparent
Ambient Color – brightness or darkness of whole material
Incandescence – create appearance of giving light
Bump mapping – makes a surface appear bumpy

6. Example of use of simple material definition and assignment

Change color of an object

1. from Windows menu select Rendering Editors -> Hypershade
   
   
   
   
2. Select create materials
3. Click Lambert (cosine shaded object)
4. Double click the new material to invoke attribute editor 
5. Select field next to color on right-hand side of screen.
6. Choose color from rgb or hsv model/accept
   
   
   
   
   
7. Drag material with middle button onto surface from icon in work are to object. Or select surface and select material with right mouse button, select “Assign Material to Selection”

6. Texture mapping nurbs surface

Prepare brick.jpg file or somephoto.jpg file. Make a material from a lamber shader. In the color selection area on the right-hand side of  the the screen, select the checkered symbol and follow the dialog box to load the brick.jpg file.

1. Nurbs surfaces U horizontal – V vertical map from lower left corner to upper right
2. Can map TIF, JPG and Maya’s IFF
3. Create Lambert material
4. In Hypershade panel double click on icon.
5. Add brick file to material
6. Select object, right click on lambert material and assign to object.
7. Double click on pace2dTexture node
8. See red square on object: middle mouse button - drag center to move, drag corners to rotate,
9. Repeat UV … to repeat pattern (do 4 in each of U and V)

7. Ramp texture (eyeball)

1. Create Phone E shader
2. Double click on the icon (gets attributes window), and then click checkerboard icon on the color.
3. In response to the dialog box to "Select a Render Node", select a "ramp" shader.
4. Change top shader to black by lowering color solider to left.
5. Move middle shader (default color is green) closer to top
6. Click on ramp 1/5th way to bottom, place new position indicator just below 2nd one (above).
7. Click and drag bottom indicator just below new one (3rd one).
8. Click on color swatch for above indicator and select white.
9. Change shader type to U Ramp if needed (rathern than a default V Ramp)and assign to sphere (in Maya 2018 it appears that you may need to try using a Type V Ramp and a type U Ramp before detemining which type is more effective).

8. Layered Shader

1. Create two blinn shaders red and blue.
2. In blue shade, double clock on icon, and then on transparency color select fractal.
3. Create layered shader
4. Double click on layered shader material.
5. With the middle mouse button drag blue and red materials from the Hypershade into the red square under Layered Shader Attributes. (note blue shader comes before red shader)
6. Click X under original green shader to remove it.
7. On blue blinn shader, use fractal to define transparency
8. Apply the shader to a sphere.
9. In Render view, click on the Redo Previous Render Icon. Red can be seen through the blue due to fractal transparency.

9. Bump Map

1. Create Lambert ahder and assign to plane via MMB.
2. Double-click on Lambert shader
3. Click map button next to bump mapping and select bulge.
4. Select render icon (upper right hand side of screen) to see bump map..
5. To change bump depth/chose graph materials on selected objects icon in hypershade panel and select lambert object.
6. Select bump2d node, increase bump depth , & render (render icon)
   
   
   

10. Projection Map

1. Create NURBS plane.
2. Create a lambert material in Hypershade and apply to plane.
3. Double-click on the lambert material in Hypershade
4. In attribute editor, click on map next to color slider.
5. Click the file button (select a file).
6. Click file1 tab at top of attribute editor.
7. Click on folder icon next to Image Name
8. Open your own image.
9. Goto perspective view and select key #6 to render.
10. Select the place2d texture utility in the hypershade window/
11. Experiment with rotate frame, repeat UV and rotate UV options.

[If surface appears to be moving through texture, then in Rendering mode, select the surface, and then from the Texturing menu select “Create Texture Reference Object”]

11. To Improve Quality of Rendering

1. Select object.
2. In hypershade panel, choose Graph Materials on Selected Objects Icon.
3. Double-click on the material in Hypershade.
4. In Attribute editor, under Hardware Texturing, click arrow to expand options.
5. Change “Texture Quality” setting to High. Only do this for temporary viewing since it slows Maya down.
   
   
   
   

11. 3D Paint Tool

1. Create Lambert material and assign it to a new NURBS sphere.
2. Select the sphere.
3. From Texturing Menu, select box next to 3D Paint Tool.
4. Scroll down until you see File Textures.
5. Click the Assign Textures button, determine resolution, and click Assign Textures {note project setup must include texture area
6. In perspective view, hold “b” key and move mouse left & right to size brush.
7. Click and drag on surface to paint.
8. Select swatch next to floor color and choose yellow at top of Color Choose.
9. Click “Flood Paint”
10. Change paint color and paint smiley face on surface.
11. Click on the change brush button, scroll down Visor and select hair folder.
12. Choose hair type and paint on to sphere.
13. Clear surface with flood button.
14. Select brush adjacent to Artisan to return to normal brush.
15. Decrease capacity of brush to see color beneath
16. Can edit image in Photoshop directly from directory.
17. [techniques can also be used for Attributes and Transparency, pull-down menu under file textures.

12. VRAY Preview

Tutorials on VRay and Maya are published on the Chaos Group Web site. We will be exploreing VRay in the next workshop and it will be covered by workshop notes 8. This Chaos Group online tutorial primer is directly relevant to our needs.