Lighting

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Arnold Lights
These lights work with the Arnold renderer only.


aiArea
Select Arnold->Lights->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
     Adjust the Exposure to 6
This image is a combination of  Ai AreaLight and Ai Skydome Light. Notice the rectangular shape of the area light reflects on the shiny objects.




aiSkydome
Select Arnold->Lights->Skydome Light
Use this light to add a background color and ambiance.
Typically the Color will be dark grey.
Keep Intensity  1 and Exposure  0
Under Visibility set Camera to 0
This keeps the background and the alpha channel transparent.
Do not use this with bump maps, there is a bug.


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




aiPhotometric
Select
Arnold->Lights->Photometric Light
Photometric lights use data measured from real-world lights.
Download IES profiles directly from light manufacturers.
This image is a combination of  Ai Photometric Light and Ai Skydome Light.



aiPhysicalSky
Select Arnold->Lights->Physical Sky
This light simulates a physical sky and sun.
In the Attribute Editor, set Exposure to 1 or more.
Under Visibility set Camera to 0
This keeps the background and the alpha channel transparent.



aiHDRSkydome    

HDR_map
Select
Arnold->Lights->Skydome Light with an HDR Image map
You can add an HDR image map.
Click on the
map icon map_button.jpg across from Color
     Click on File
     Select an image (you can use the image above)
In the Attribute Editor set Exposure to 1
Under Visibility set Camera to 0
This keeps the background and the alpha channel transparent.




aiGobo_Fog
Fog with Spot Lights

Select Create->Lights->
Spot Light


Select your spot light in the perspective view
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.
Click the circle with a line to switch between manipulators.
Use your mouse to drag the end of the cone longer.

In the Attribute Editor
Input a negative Penumbra Angle.

Under the Arnold drop-down
     Set Exposure to 1
Under the Light Filters drop-down, click on Add
Select aiGobo and click Add
On the aiGobo tab in the Attribute Editor
     Set the Filter Mode to mix and Density to 1

Open the Render Settings, under the Arnold Renderer tab, open Environment
     Select the map_button.jpg icon to the right of Atmosphere
    Choose Craaete aiAtmosphereVolume
In the Attribute Editor
          Input Density 1 or more
This image is a combination of  a Spot Light and Ai Skydome Light.



aiLightPortal
Select Arnold->Lights->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.

Select Arnold->Lights->Light Portal
Place the Light Portal so that it covers the entire window and points inwards.
This image is a combination of  a Light Portal and Skydome Light.



Render Settings.
Press this icon upper right or middle  srender_settings
Under the Common tab:
Under the File Output
arrow:
Choose Image format: Tif
Uncheck Dither


With these settings below, your scene will render faster with a preview quality.
Under the Arnold Renderer tab:
Under the Sampling arrow:
     Set Camera (AA) to 2      (default 3)
     Set Diffuse to 2      (default 2)
     Set Specular to 1      (default 2)
     Set Transmission to 0      (
default 2)
     Set SSS to 0      (
default 2)
     Set Volume Indirect to 0      (
default 2)

Under the Ray Depth arrow
     Set Total to 1      (
default 10)
     Set Diffuse
to 1      (
default 1)
     Set Specular
to 1      (
default 1)
     Set Transmisssion
to 0      (
default 8)
     Set Volume
to 0      (
default 0)
     Set Transparency Depth
to 0      (
default 10)

Click Close
to close the window



Maya Software Render Lights
Maya software render is slower with newer computers, it does not utilize the new processors and graphics cards. (Maya Renderer can be faster with old processors.)
These lights work with Maya, Arnold and Mental Ray.
g_point.jpg
Select Create->Lights->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 Lights 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
Select Create->Lights->Directional Light
This light will work in Unity. None of the other lights work in Unity.
This light has no attenuation, it similar to our sun. Everything in the scene is illuminated equally.

Set the intensity of this light at 1.2
units.
Use rotate to change the direction of the light.
The location of the light does not matter as it does not change the shadows or highlights.



g_ambient.jpg
Select Create->Lights->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
Select Create->Lights->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, use the gobo above procedure for 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
Select Create->Lights->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. You will to change the intensity of you scale this light. 
If raytraced this light can produce soft shadows, this can take a long time to render.
When rendering with Arnold: under the Arnold drop-down change the Exposure to 6.



g_volume.jpgr
Select Create->Lights->Volume Light
(Works with Maya Software Render and 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.



Mental Ray Lights
Most of these lights work with the Maya Software render and the Mental Ray Renderer, supported up to Maya 2018.

Install plug-in, if you do not see Mental Ray options
Download the plugin from:
https://forum.nvidia-arc.com/showthread.php?16283-Now-Available-Mental-Ray-for-Maya-2018
Mental Ray is a plug-in for Maya, 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 the Loaded box and Auto Load box next to Mayatomr.mll

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 gray

Open
Render Settings
srender_settings
Under the Quality tab
     Change
Indirect Diffuse (GI) Mode to  Finalgather
     This gets rid of graininess.



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


mrPhysicalAreaLight
Select 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, this 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.
srender_settings
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.
srender_settings
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.