Maya: Lighting

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Set Up
Turn off Color Management:
Select Windows->Settings/Preferences->Preferences
Select Color Management
Uncheck Enable Color Management
Select Save


Arnold Lights

These lights only work with the Arnold renderer.
Select Arnold->Lights

aiArea
Ai Area Light
T
his light can be scaled to change the shape of the light; it also needs to point at the scene, you may need to rotate and position it.
Under the lights attributes: set the Intensity to 1. Set the exposure to  if you scaled the light, you may need to adjust the exposure.
This image is a combination of  Ai AreaLight and Ai Skydome Light.Notice the area light reflects on the shiny objects.



aiSkydome
Ai Skydome Light
Use this light to add a background color and ambiance. Make the color white.
Keep Intensity to 1 and Exposure to 0.



aiMesh
Ai Mesh Light
Mesh lights can be used to turn polygonal surfaces into light emitting objects. (NURBS surfaces do not work with mesh light.)
First select a mesh and go to Arnold>Lights>Mesh Light
Set the intensity to 1 and Exposure to 5. Check the Light Visible option and set the samples to 4.
This image is a combination of  Ai Mesh Light and Ai Skydome Light.



aiPhotometric
Ai Photometric Light
Photometric lights use data measured from real-world lights. You can download IES profiles directly from light manufacturers.
This image is a combination of  Ai Photometric Light and Ai Skydome Light.



aiPhysicalSky
Ai Physical Sky
This light simulates a physical sky and sun.
In the Attribute Editor, set Exposure to 1 or more.
In the Render Settings window, change the Arnold Renderer tab-> Camera (AA) to 7 to clean up the noise.
(Everything else can be set to 1.)



aiHDRSkydome     HDR_map
Ai Skydome light with HDR Image map
The Skydome light has a texturable color slot where you can add an HDR image map.
Click on the map icon
map_button.jpg across from color.
Under the Render Node Window, click on File
Select an image (you can save the image above)
In the Attribute Editor, set Exposure to 1. In the Render Settings, change the Camera (AA) to 7.

Render without Environment Background

You will still have the ambient light affecting your scene.
Select the aiSkydome Light in the Outliner menu
In the Attribute Editor under Visibility, change the Camera value to 0





aiGobo_Fog
Fog with Spot Lights
Create>Lights>
Spot Light

Arnold uses a Light Filter called Gobo that can be applied to a spot light.
Any texture map or procedural shader can also be projected through the light.
Select your spot light. In the perspective window, select
Panels->Look through Selected.
Dolly and track the view to look at your objects. This will aim the light at the objects in your scene.
Use Panels->Perspective->Persp to bring the window back.

Select the light and use Display->Show->Light Manipulators to turn on controls.
Use your mouse to drag the end of the cone longer.

Click the circle with a line to switch between manipulators.

In the Attribute Editor
Input a negative Penumbra Angle.
Dropoff should be 0.
Under the Arnold drop-down, set Exposure to 7
Under the Light Filters drop-down, click on Add
Select aiGobo and click Add
On the aiGobo tab on the Attribute Editor:
Set the Filter Mode to Mix and Density to 1
Open the Render Settings, and go to Environment under the Arnold Renderer tab:
Create an aiAtmosphere Volume
 by selecting the map_button.jpg icon to the right of Atmosphere.
This image is a combination of  a Spot Light and Ai Skydome Light.



aiLightPortal
Ai Light Portal
Skydome lights can use light portals to reduce noise for interior  scenes, where the light comes in through relatively small openings. 
Instead of emitting light, they can be used to guide skydome light sampling.
Light portals must be placed to cover all windows, doors and other openings through which skydome light comes into the scene.

Place a Create>Lights>Spot Light outside of a Window in an Interior Scene
Select Arnold>Lights>Light Portal
Place the Light Portal so that it covers the entire window and points inwards.
Under the Arnold drop-down, set Exposure to 7
Open the Render Settings, and go to Environment under the Arnold Renderer tab:
Create an aiAtmosphere Volume
 by selecting the map_button.jpg icon to the right of Atmosphere
This image is a combination of  a Spot Light, a Light Portal and Skydome Light.



Mental Ray Lights
These lights work with the Mental Ray Renderer.

Install plugin, if you do not see Mental Ray options
Keep in mind that Autodesk did not develop Mental Ray; it is a plug-in for Maya, so you may have to enable it in the Plug-in Manager before you can see it as an option in your Render Settings window.
     To enable the plug-in:  Window>Settings/Preferences>Plug-in Manager
    
Check both the Loaded box and the Auto Load box next to Mayatomr.mll and xgenMR.py

mrEnvironment_before   mrEnvironment
Environment Based Lighting
This creates ambiance by changing the environment's background color.
Select the Render Camera:
     In the perspective view, choose View->Camera Attribute Editor...
          Under Environment, change the background color to grey
Open the Render Settings:
Under the Common tab, click on the Render Options drop-down and uncheck Enable Default Light.
Under the Scene tab, click on the Environment drop-down and check Emit Environment Light
In order to get rid of the graininess, increase the Overall Quality, Lighting Quality, and Environment Lighting Quality to 1 under the Quality tab in the Render Settings.
WARNING!! This is a really slow way to render. Uncheck Emit Environment Light


mrObjectLight
Object Light
Mesh lights can be used to turn polygonal surfaces into light emitting objects. NURBS surfaces do not work with mesh light.
First select a mesh and go to Create>Lights>Object Light
Set the intensity
to 100
This image is a combination of Environment lighting and Object Light
.



mrPhysicalAreaLight
Physical Area Light
Create>Lights>Physical Area Light
This light can be scaled to change the shape of the light.
Set the Intensity of this light to 100. 
If raytraced this light can produce soft shadows, although it can take a long time to render.
This image is a combination of Environment lighting and Physical Area Light



mrPhysicalSun
Physical Sun
The best way to access this light is thru the Render Settings window.
Under the Scene tab in the Environment drop-down, click on the Create button next to Physical Sun and Sky
Set the Intensity to 1



mrImageBasedLighting    HDR_map

Image Based Lighting
Access this light thru the Render Settings window.
Under the Scene tab in the Environment drop-down, click on the Create button next to Image Based Lighting
Add a HDR image file to the Image Name
You can use the Hypershade Editor->Utilities tab to look at the environment later:  hypershade
     Under Attribute Editor: mentalrayShape tab->Light Emission drop-down: Emit Light should be checked off (it slows down the render)


Mental Ray Notes:
Render Settings->Scene tab    Emit Environment Light can slow down a render a lot.
If you do use Emit Environment Light, check the Env. Lighting Quality settings in the Quality tab for Environment Light.
Render Settings->Common tab->Render Options  Make Sure to turn off Default Lights



Maya Software Render Lights

Maya software render is slower on newer computers, it does not utilize the new processors and graphics cards.
g_point.jpg
Point Light
This light is like a light bulb, it points in all directions. A good default intensity is 1.2
When rendering with Arnold: under the Arnold drop-down change the Exposure to 6



g_light_decay
Linear Decay
(This decay works with Mental Ray and Maya Software render, not Arnold)
In the attribute editor for the point light, select Decay Rate->Linear

Use Create->Measure Tools->Distance Tool to measure the distance between the light and the object you would like illuminated.
Use this value for the Light's Intensity, you can input a value above the slider.
Play with Quadratic, you will need to turn up the intensity to over 100.




g_directional.jpg
Directional Light
This light has no attenuation, it similar to our sun. Everything in the scene is illuminated equally.
Leave the intensity of this light at 1 unit. When rendering with Arnold the exposure should be set to 1 (under Arnold drop-down).
Use rotate to change the direction of the light.
The location of the light does not matter as it does not change the attribute of the light.



g_ambient.jpg
Ambient Light
(Works with Mental Ray and Maya Software render, not  Arnold )
This light works well as a fill light. It helps illuminate dark shadow areas that can tend to make an object flat.
No highlights. Avoid using this light as the key light, it tends to be very low contrast. The default settings are bad, set the color to a dark gray.



g_spot.jpg
Spot Light
This light creates a cone of light, notice the ring of light on the ground. Leave the intensity of this light at 1 unit.
When rendering with Arnold: under the Arnold drop-down change the Exposure to 6.
spot_light_controls
Fog with Spot Lights
(Works with Mental Ray, not  Arnold )
Select your spot light. In the perspective window, select Panels->Look through Selected.
Dolly and track the view to look at your objects. This will aim the light at the objects in your scene.
Use Panels->Perspective->Persp to bring the window back.

Select the light and use Display->Show->Light Manipulators to turn on controls.
Use your mouse to drag the end of the cone longer.

Click the circle with a line to switch between manipulators.

In the Attribute Editor
Input a negative Penumbra Angle.
Input Dropoff 10
Under
Light Effects
, click the map button map_button next to Light Fog.

Under Shadows, under Raytrace Shadow Attributes
Select Use Ray Trace Shadows
Input Light radius .15 for soft shadows
Input
Shadow rays 40, to fix speckels

spot_light_fog



g_area.jpg
Area Light
This light can be scaled to change the shape of the light.  Notice the long rectangular highlights. Set the Intensity of this light to 1.2. 
If raytraced this light can produce soft shadows, although it can take a long time to render.
When rendering with Arnold: under the Arnold drop-down change the Exposure to 6.



g_volume.jpgr
Volume Light
(Works with Mental Ray, not  Arnold )
This light can be scaled to change the shape of the light. Object must be inside the light to be illuminated.  
Notice the beam of light, this was created with a box shaped area light, squished in the Z axis.



Raytraced Shadows
Open Windows->Rendering Editors->Render Settings... render_settings_button
Under Maya Software tab:
Under Raytracing Quality
    
Check  Raytracing
    
Input Shadows 2
    
Input Bias .2 This will make round objects look less jaggy.