October 22, 2015 Workshop 11 Notes
LIGHTING
AND MATERIALS, RENDER FARMING
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:
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
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.
Once the image map has been loaded into the definition of the material, it is included in the symbolic graph of the material (left-hand side of image below). Double-clicking on the Place2D texture tool activates interactive placement options.7. Ramp texture (eyeball)
8. Layered Shader
9. Bump Map
10.
Projection Map
[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
11. 3D Paint Tool
RENDER FARMING
The render farm server containts a cluster of central processing units for concentrated rendering. The render farm is launched from a utility named "BackBurner" within Maya and must be used within a restricted set of file lcoations, but doesn't require you to remain logged in to view the result. Details on the use of the render server are describe in the link below. Before trying to use the render server see important warning below.
WARNING: Due to administrative restrictions on our system, it is essential that within the dialog for BackBurner, DO NOT check the option to "Manually Start Job" (see image below for a correct setting with "Manually Start Job" unchecked). If you do check on this option, then it will suspend the job and block the queue for other jobs sent to the render server. Only a system administrator will be able to clear the job and this could cause a significant disruption to all users of the system.