Wednesday, April 7, 2010

Anisotropic: metal, compact discs (cd's) or hair

Blinn: metal surfaces but I end up using blinn for almost every object type (basically blinn can be modified to be used for almost anything at all.)

Hair Tube Shader: The shader attributes are similar to the anisotropic shader in terms of the the specularity control... besides that it's the basic Blinn shader attributes, with a few extras.
*Maya Help files say:
If you convert your Paint Effects hair system to polygons, then a default Paint Effects tube shader is created. The former color attributes you set in the hair system are converted to the tube shader, but there is no construction history for these attributes. Any shading changes you want to make after you convert Paint Effects to polygons must be done using the tube shader.

Lambert: nothing. lol well not nothing, i guess you can use it for chalk, or really dull objects... I recomend just using the Blinn shader then turn down all the specularity and reflections, to get the same effect, just with more control.

Layered Shader: allows you to use different shader types, and stack them into layers much similar to how you would with photoshop layers

Ocean Shader: water, oceans. It's attributes control things like wave size, strength, speed, etc... it's pretty straight forward for the most part.

Phong: Plastic, or tiles, or anything that has a high gloss look to it.

Phong E: same as Phong except with different specularity controls. not really any difference...just personal preference.

Ramp Shader: allows you to create cartoon type shaders, or subtle rim-light effects, etc... I usually just use it for cartoon characters if you want it to look like 2d animation/renders. But it can also be used to control the colours falloff, etc without having to deal with the sampler info node etc.

Shading Map: is used for custom shaders. I used to use it for custom cartoon shader before the ramp shader came standard with maya. You can also connect other shaders to this node such as lambert, blinn, etc...

Surface Shader: is used for custom shaders as well, along with some render passes tricks, etc.
*edit* this is what the maya help files say:
Is a material (shader) that is a wrapper node, which means that you can connect any keyable attribute to this shading group, and then connect the shading group to an object. For example, you can connect an object's Translate Position to a Surface Shader's Out Color attribute to determine the object's color by the object's position.

Use Background: I have no idea, I never used this shader in my Life. I think it has something to do with compositing photo/film footage within the 3d scene. The object won't show up in a render, but it will take on shadows, and reflections, etc..
I'll have to research this shader more ... F1/help is my best friend, so is google :P
---------------------Common Material Attributes----------------------



Color - sets the color of the shader. This can be textured, or combination of Utility Nodes can be applied to give different effects to the color shader.
Transparency - Black=0 White=1; you can choose just a color value between 0-1 or create a more complex texture to give your object a unique transparent pattern/shape.
Ambient Color - (maya says) is black by default, which means it does not affect the material's over-all color. As the ambient color becomes brighter, it affects the material's color by lightening it and blending the two colors.

If there are ambient lights in the scene, then the color and brightness of those lights are used to control how much the ambient color contributes to the final color of the material.

Incandescence - basically makes the shader appear to have it's own light source. But do not mistake it as a light source. (unless using Mental Ray) By default it's black, so no self illumination, but if you give it a value, it will only affect itself, no other shaders or materials.

Bump Mapping - Simulates a 3-dimensional surface detail. Creating the "illusion" of bumps, and scratches, etc. *NOTE: this does not physically affect the shape of the object. if you are looking to do that, Check out "displacement mapping"

Diffuse - Controls how much light in the scene is "scattered" off the object. So how much light is absorbed by the object, and then the rest is scattered off. Black is all absorbed (making the object darker) and White is all scattered light (making the object lighter) This can be mapped like any other channel. Usually you use it in conjunction with Color, Spec, and Bump.

(maya says
Translucence - Simulates the way light diffusely penetrates through translucent objects. This means that when light shines on one side of the object, the other side is partially illuminated. This can be used for effects such as clouds, fur, hair, marble, jade, wax, paper, leaves, etc.

If Translucence is set to 0 (the default) then no light shows through the object. If it is set to 1, all the light shows through.

Translucence Focus- Simulates the way light scatters more in a forward direction through translucent objects. Thin objects like a leaf, or low density objects like a cloud tend to scatter more in a forward direction.

When the Translucence Focus is 0.0, translucent light is scattered in all directions. As the focus value is raised the translucent light is scatter more in the light direction. This makes the backlit side of a leaf glow more than the front lit side. At high focus values you will see a halo or glow around the light source when seen through a translucent object.

Translucence Depth- Defines the depth of penetration into an object at which translucence decays to nothing.

When Translucence Depth is 0, translucence does not decay with respect to the distance light travels through the object.




----------------------------Specular Shading --------------------------




Eccentricity - changes the size of the shiny highlights.

Specular Roll Off - changes the blend between the highlights and the non highlighted parts of the surface.

Specular Color - the color of the highlights of an object. *NOTE: for plastic shiny surfaces, use a white-ish color. For Metal use the same color as your color channel, but crank the value up over 1

Reflectivity - (maya says) Gives the surface the ability to reflect its surroundings or the Reflected Color (similar to Specular Roll Off). The valid range is 0 to infinity. The slider range is 0 (no reflections) to 1 (clear reflections). The default value is 0.5.

Reflectivity values for common surface materials are car paint (0.4), glass (0.7), mirror (1), chrome (1).


Reflected Color - is the color of light reflected from the material. When raytracing, this color will mix (multiplies) with the color of your light, allowing you to "tint" the reflection.
*NOTE:
If you are not raytracing, you can map an image, texture, or environment map to the Reflected Color attribute to create fake reflections, which is faster and uses less memory than raytracing.




--------------------------------Special Effects -----------------------




Hide Source - if this is checked on, you will not see your geometry, just the the glow in the shape of your object. If it's off, you will see both your object and your glow.

Glow Intensity - is a multiplier to the GLOW SHADER (check out glow shader for more glow attributes)
*NOTE: do not get this confused with the incandescence attribute. Glow is addes as a post-process, Meaning that it is applied after the render is done. Incandescence is applied during the main rendering and does not actually make your surface glow, but rather make it appear "brighter"
The Glow will add a halo around your surface. Something Incandescence cannot do.
*NOTE: if you use the glow shader, take off the "auto exposure" in the glow shader attributes, if you do not, you will get flickering in your animation. and make your glow look inconsistant.



----------------------------------Matte Opacity -----------------------



This is mostly used for compositing. I do not have a lot of knowledge on this subject but, Basically it controls your alpha masks for that object. allowing you to change/animate the channels for compositing needs.

BLACK HOLE: maya sets the channels mask value to zero. if the object has transparency's in it. any objects behind it will not appear in the mask channel (alpha channel)

OPACITY GAIN: Sets the channels mask, then Multiplies the mask values for the object by the matte opacity values. so if the matte opacity is 1. it stays unchanged. If it's 0.5 the mask values for the object are half their original settings.
SOLID MATTE: sets the mask to a constant value. If object is transparent, any objects behind it will appear in the mask channel (alpha channel)




------------------------------Raytrace Options --------------------------



Refractions: turned off by default. if turned on, it will make your shader refract light when rendering in ray tracing. You will not see a difference if the REFRACTIVE INDEX is set to 1.
Refractive Index : Default is 1 (nothing changes)
It defines how much a ray of light bends when it passes through your object. This will only work if you have a partially or completely transparent object.
Index Presets:
Air: 1.0
Water: 1.33
Gasoline: 1.45
Crystal: 2.00
Glass: 1.5
Ice: 1.309
Quartz: 1.6
Ruby: 1.77
Sapphire: 1.77
Salt: 1.54
Alcohol: 1.329
Emerald: 1.57
Polystyrene: 1.55

Refraction Limit: Maya files say Ray Depth Limit. which i think means how many times a ray of light can pass through a surface. just remember the higher the number is, the slower the render.
*NOTE: To simulate realistic looking glass, set the Refraction Limit value to 9 or 10.

Light Absorbance: How light-absorbing the material is. so if the value is zero, it allows light to go through completely. and the higher the value, the less light passes through.
*NOTE: the thicker a material, the less light gets through. the thinner it is, the more the light will go through.

Surface Thickness: simulates the thickness of a transparent object used for things enclosed surfaces, for example; like a window or windshield. it won't work as well as an actual modelled window pane.

Shadow Attenuation: Simulates caustics. for example liquid or glass shadows have a brighter center. simulating "focused light".
Values go from zero to one. 0-1. 0.5 is default. to turn it off use zero. the closer to 1 the more intense the shadow's bright center gets intense.

Chromatic Aberration: (maya says) Different wavelengths of light refract at different angles when passing through a transparent surface during raytracing. Chromatic Aberration only affects light rays as they pass through the second surface of a transparent object (the first exit ray).
So, it doesn't affect the light unless it's leaving an object... going in only, it does nothing.




-------------------------------Vector Renderer Control -------------------



*need to activate the vector renderer in WINDOW>SETTINGS/PREFERENCES>PLUG-IN MANAGER
once activated go to render globals and choose it like you would for Mental Ray.
All the attributes are really quite forward. You can do default settings, in the render settings window.
or customize them per object by selecting the "Overwrite Default Values" in the shaders "Vector Renderer Control"




---------------------------------Mental Ray ----------------------------





Reflection/Refraction Blur: (maya says)Determines the blurriness of the reflection or refraction by calculating the angle (in degrees) between the perfect reflection or refraction direction and the jittered ray direction. A value of 0 creates a perfectly specular interaction; a value of 90 a perfectly diffuse reflection or refraction. Values of 10 to 30 are good starting points.

Reflection/Refraction Rays: Defines how many rays to use to sample the random deviation from the perfect specular direction.
*NOTE: In general, more rays are required for more blurry reflections or refractions. Other sampling parameters also affect this setting: per-object samples and the Render Settings sample setting supersample in image space. If you increase any of these two settings, you may be able to reduce the number of rays without loss of quality, while significantly improving performance.

Irradiance: the ability to bounce indirect photons. (maya help files suggests using this with baking illumination and color.
*I don't know a lot on this subject so I can't add to this section. yet.

Irradiance Color: the color of the bounced photons.

This next one isn't on the blinn shader but it can be useful if you run across it when rendering with mental ray:

Occlusion Mask:Lets you see the soft shadow, produced by final gathering, of an object on a surface that uses the Use Background shader. These soft shadows are also captured in the alpha channel of the image for compositing purposes.

You can set values for Occlusion Mask between 0 (no shadows) to 1 (full shadows), or map the attribute.



Photon Attributes: Set attributes to Derive From Maya, or turn the option off and set remaining attributes, such as Specular Color and Diffuse, so that they are calculated using mental ray. Alternatively, you can change the settings in the Maya sections of the Attribute Editor (Common Material Attributes, and so on) and click Take Settings From Maya to compute the equivalent mental ray values for these attributes.





------------------------------------Node Behavior ----------------------



Caching: turn caching on to temporarily store the nodes input evaluations in a cache file. Whenever maya needs this information it is quickly accessed from this cache file, instead of having to re-calculate the nodes input.
*NOTE: the cache file is destroyed when you change an attribute. Also, Caching uses more memory, which could affect maya's performance.

(maya says)
Node State:
Normal- Causes the node to behave normally, according to the defined settings and effects. This is the default.

HasNoEffect - Disables any effects on the node so that fewer calculations are necessary at the time of redraw. The effect does not render until you reset the Node State back to Normal. Maya evaluates the nodes in the node's history, but not the node itself.

For example, if you translate a cluster to deform a geometry, then set the Node State of the cluster node to HasNoEffect, the geometry appears undeformed, as though the translation had not occurred. To view the effect, change the Node State back to Normal.

Blocking - Temporarily hides the node and does not display the results of any input (input evaluations) to the node. This can speed the redraw. It is also useful when you have complex scenes and want to edit only one aspect of a node. Blocked nodes do not render.

For example, if you have a complex revolved surface and want to edit the curve, but don't want to wait while the curve redraws, select Blocking and edit the curve. To display the modified revolved surface, reset the Node State to Normal.

*NOTE:

* The "HasNoEffect" state has a different meaning for each node type. Some node types do not implement the state, in which case the state acts just like "Normal".
* The "Waiting" node states are used internally by Maya to keep track of nodes that are waiting for a view update in the Hypergraph. You should not normally set nodes to a "Waiting" state.




---------------------------------Hardware Shading --------------------



no idea
it doesn't show up in renders...
Possibly affect hardware renders? *not sure*



------------------------------Hardware Texturing-----------------------



allows you to preview your textures and channels right in your viewport only, it doesn't change how the objects render.
Glows and Bumps will not show up in this you'll need to render the scene to see those effects.



------------------------------------Extra Attributes --------------------



any custom attributes you've added through ATTRIBUTES>ADD ATTRIBUTES

Monday, March 8, 2010

ambient occlusion

http://www.game-artist.net/forums/spotlight-articles/1317-tutorial-ambient-occlusion-maya-alchemist101.html

Saturday, March 6, 2010

set driven key

http://caad.arch.ethz.ch/info/maya/manual/UserGuide/Animation/KeyframeMoPath/03_understanding_key.doc5.html

Thursday, February 4, 2010

update

Just changed the template of my blog so that I can post bigger images. I had to resize them to smaller than 400px in width before...no more of that.
I'll post up pictures of my character design and layouts soon.

Tuesday, January 26, 2010

on lighting

http://www.itchy-animation.co.uk/tutorials/light.htm

http://www.3dtotal.com/team/Tutorials_3/basic_maya_lighting/basic_maya02.php

http://warpedspace.org/lightingT/part1.htm

http://www.creativecrash.com/maya/tutorials/rendering-lighting/c/faking-global-illumination