Lecture 3: Spatial data photointerpretation and basic color theory

1
Tuesday, 13 January
Lecture 3 Spatial data - photointerpretation and
basic color theory
http//webvision.med.utah.edu/KallColor.html
(to Opponent Color Theory above Fig. 15) -
color theory http//www.bway.net/jscruggs/film.h
tml - color film (short)
2
Previous lecture Photographs and digital
images Structure of brightness elements in
images Detection Resolution Signal noise Point
extended targets
3
Photo Interpretation
Color Separation Images
What is the role of textural information
in photo- interpretation?
4
Full spatial information
5
What can be said in B/W? What can be said about
color alone? Where does most of the useful
information come from?
6
Color
Color is a sensation that can be predicted and
controlled Color has 3 dimensions and can be
simulated by radiances at three different
ls In natural color those are red, green and
blue but In remote sensing any 3 may be combined
as a false-color image Therefore we need to
understand color Color is created by selective
absorption, so we need to understand that first
7
The electromagnetic spectrum
Light is energy - Q hn in ergs or joules (J)
where h Plancks constant, 6.6310-34 J s n
frequency (s-1) c/l (c speed of light,
3.00x108 ms-1, l wavelength (µm,nm,mm,cm,m)
For SI units frequently used in Remote Sensing,
see back cover of text
8
Lets start with how humans sense color Cells
within the eye absorb light of 3 wavelength
ranges RGB They send signals to the brain
proportional to how much light is
absorbed The brain turns these signals into
the sensation of color Color has three
attributes hue, saturation, and intensity or
lightness color (perception) is related to
radiance (physical flux)
9
(No Transcript)
10
Additive Color
11
Additive Color

Spectral yellow
12
Additive mixtures
g
r
b
13
A D D I T I V E M I X I N G
14
Additive mixing
15
Additive mixing
16
Lighting, viewing geometry, resolution
17
(No Transcript)
18
Expanding the FOV adds contextual information
Apollo capsule
19
What cues indicate the direction of the sun?
20
Familiar scenes are interpreted more easily
21
Illuminated DEM
What information is present in a B/W image beyond
shape and lighting alone?
B/W image
22
(No Transcript)
23
Death Valley, California
Natural Color
Not much more color information than on the Moon
24
Mt. Rainier
25
Amazon
July
January
26
Surfaces from Lidar Data
1) Canopy Top (Hillshade Treeshade)
2
3
1
2) Bare Earth (Hillshade Only)

3) Tree Height (Treeshade Only)
0
500
N
Approx. Scale (meters)
27
What can be said in B/W? What can be said about
color alone? Where does most of the useful
information come from?
28

• Next lecture
• The spectrum
• Color theory
• Absorption,
• Photogrammetry