Importance of the night sky

1
Introduction

• Importance of the night sky
• Ambiance of night scenes
• Applications
• Films, planetarium shows, simulators, games

2
Sources of Illumination (W/m2)

• Sun 103
• Moon 10-3
• Stars 10-8

• Zodiacal light 10-7
• Airglow 10-8
• Cosmic light 10-10
• Dim misc. 10 -8 10-9

3
Model Overview
4
Moon Position

• 59 of the Moon is visible from the Earth
• Rotates around itself at the same speed as around
  the Earth
• Elliptical orbit

5
Modeling the Moon
Data from the Clementine project

• Geometric model
• Albedo map
• Elevation map
• Illuminated by
• Sun (black body)
• Earth (earthshine)
• Specialized BRDF

6
BRDF of the Moon

• Low albedo (7)
• Reddish color
• Backscattering (much brighter at full moon)
• No limb darkening (uniform disc at full moon)
• Constant across the surface
• We decouple BRDF, spectral properties and albedo

Photo by Antonio Cidadao
7
Low Moon over cityscape
8
Close-up of rendered stars
9
Fish-eye view of a clear, moonless night
10
Time-lapse rendering of stars
11
Moon and stars over the Little Matterhorn
12
Moon rising above a mountain
13
Full Moon with thin layer of clouds
14
Gibbous Moon
15
Earthshine
16
Quarter moon with daylight
17
Zodiacal light