Lighting Practice 2: Atmosphere

Desert Haze

The above render was created using only a directional light and aifog. I was surprised at the atmosphere's effectiveness; an orange tint immediately transported the scene into a desert storm.  

Process:

- create a directional light, rotate to face the scene. Exposure:1  Angle:5  Samples:5

- change background colour in Arnold Render view to orange.

- render settings > Arnold > environment > aiatmosphere > aifog.  

- aifog1  distance:0.001   Height:50  Ground normal:1 in Y axis. 

- set fog colour to orange.

Volumetric Light Rays

Above, a render of the same scene now using a spot light and atmosphere volume. Light rays are achieved with a noise Gobo, which works like acetate over a torch. Atmosphere anisotropy, attenuation and colour balance were important focus points for this outcome. 

Process: 

- render settings > arnold > environment > aiatmosphere > aiatmospherevolume.

- density: 0.8  colour: navy blue  attenuation:0.102  attenuation colour: red  anisotropy:-0.651 samples:5

- create spot light > position at translate Y:25 > direct at the scene.

- code angle:70  penumbra:-16  dropoff:8  exposure:30  samples:5

- aiatmosphere volume colouring works in contrast; colour hue must be the opposite to attenuation colour hue. In this instance, red and blue. 

- select spotlight > light filters > gobo > slide map > add noise

- noise  amplitude:0.001  ratio:0.4  frequency ratio:10  frequency:60

Volumetric Deep Sea

This third render uses atmosphere volume and a spotlight once again. This time, a caustics gobo was applied. The atmosphere volume decays the caustics and, with a murky blue applied, gives the illusion of a deep sea scene. 

Process:

- create spot light facing the scene > penumbra:-16  code angle:74  dropoff:8  exposure:25
- freecausticsgenerator.com > download 1.4 and open > size:1024  super sampling:4x  motion blur:5  background colour:0  no.of frames:50

- save out sequence in directory > click render animation.

- open after effects > preferences > sequence footage import > 25fps

- drag sequence into timeline > brightness and contrast fx  brightness fx:27  contrast:29

- add blur fx  blur radius:3

- composition > add to render que > lossless > format: TIFF (turn off both boxes) > output > save to directory appropriately, replacing underscores with full stops.

- lossless > out module - video output > untick box > starting no:1

- re-open Maya > spot light filters ) gobo > colour checker box > file > tick image sequence > choose first file of sequence.

- colour balance > increase exposure > place 2D texture > repeat UV:2

- pre and post infinity: cycle

- input and output type table: linear

- create an area light > move above scene, facing downwards > change colour to murky green

- exposure:22  samples:3

- Add a blue tint to caustics

When multiple frames are rendered from this sequence, the caustics will move. 

Notes

- Clamping AA samples in the render settings removes fireflies in renders. 

- When increasing samples, the order is: atmosphere first, then lights, then shadows, and camera last.