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FOR 220 Aerial Photo Interpretation and Forest
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Lecture 15 Photo Interpretation
Paine (1981) Chapters 13 and 17 Paine and Kiser
(2003) Chapters 15 and 21
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Photo Interpretation
Defined
The act of examining photographic images for the
purpose of identifying objects and judging their
significance.
Objective
To be able to recognize landscape features on a
aerial photograph and make inferences about the
environment.
Requirements

• Long hours of practice
• Ground visitations
• Have a background in earth sciences and
  biological sciences

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Photo Interpretation
Paine lists seven principles of
photointerpretation

• Size (Relative or Absolute)
• Shape
• Shadows
• Tone or Color
• Texture
• Pattern
• Association/Location

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Photo Interpretation Seven Basic Principles
Principle 1 Absolute and Relative Size
Relative size the size of an unknown object in
relation to the size of a known
object. Absolute size the actual size of a
landscape features, requires an understanding of
the photo scale.
From Paine 1981
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Photo Interpretation Seven Basic Principles
Principle 1 Absolute and Relative Size
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Photo Interpretation Seven Basic Principles
Principle 2 Shape
We must be able to recognize landscape features
on a photograph by their shape as viewed from
above. Example transportation systems and
their type railroad, highway, secondary
roads Example vegetation powerlines, airport
runways
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Photo Interpretation Seven Basic Principles
Principle 2 Shape
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Photo Interpretation Seven Basic Principles
Principle 3 Shadows
Give clues to the profile shape and relative
sizes of landscape features. Can obscure detail
in other landscape features.
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Photo Interpretation Seven Basic Principles
Principle 4 Tone or Color
Remember BW photography about 200 shades of
gray Color photography thousands of shades of
color Tone is described in terms of
pattern uniform, mottled, banded, etc. .....
and in terms of boundary sharpness sharp,
distinct, gradual, fuzzy Tone (and color) varies
both within and between photographs, between
seasons of the year, and with the position of the
sun in relation to the camera.
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Photo Interpretation Seven Basic Principles
Principle 4 Tone or Color Black and White Images
Panchromatic
BW Infrared
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Photo Interpretation Seven Basic Principles
Principle 4 Tone or Color Color Images
Natural (Visible Spectrum)
Color Infrared
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Photo Interpretation Seven Basic Principles
Principle 5 Texture
The result of changes in tone, or the arrangement
of tone on a landscape Textures very fine,
fine, medium, coarse, very coarse
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Photo Interpretation Seven Basic Principles
Principle 5 Texture
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Photo Interpretation Seven Basic Principles
Principle 5 Texture
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Photo Interpretation Seven Basic Principles
Principle 5 Texture
In General
Forests spectrum of textures Grasslands
typically have very fine textures. Shrublands/cha
pparal have medium textures.
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Photo Interpretation Seven Basic Principles
Principle 6 Pattern
The spatial arrangement of objects on a
landscape Human-made well-defined geometric
patterns made up of smooth lines and
curves Natural not as uniform
How is pattern different than texture?
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Photo Interpretation Seven Basic Principles
Principle 6 Pattern
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Photo Interpretation Seven Basic Principles
Principle 6 Pattern
Which one is yours?
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Photo Interpretation Seven Basic Principles
Principle 6 Pattern
Whats going on here?
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Photo Interpretation Seven Basic Principles
Principle 6 Pattern
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Photo Interpretation Seven Basic Principles
Principle 6 Pattern
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Photo Interpretation Seven Basic Principles
Principle 7 Location, Association, Convergence
of Evidence
A reasoning process to relate an object to its
surroundings. Biological association is
important in resource management. Requires
knowledge of biological and geomorphic
processes. Uses shape, size, textural, pattern,
and tonal/color information.
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Photo Interpretation Seven Basic Principles
Principle 7 Location, Association, Convergence
of Evidence
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Photo Interpretation Seven Basic Principles
Principle 7 Location, Association, Convergence
of Evidence
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Photo Interpretation Seven Basic Principles
Principle 7 Location, Association, Convergence
of Evidence
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Photo Interpretation Seven Basic Principles
Principle 7 Location, Association, Convergence
of Evidence
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Photo Interpretation Techniques
Stereoscopic Examination
Three-dimensional viewing is essential for
certain interpretation tasks. More detail can be
observed stereoscopically than without.
Stereograms / Interpretation keys
Identification examples. Something to compare
what you are seeing against.
Magnification
Enhancement of images is a valuable tool. Grain
of imagery may become noticeable, and render the
interpretation useless.
Photo Measurements
Help define the scale / size of landscape features
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Photo Interpretation Techniques
Conversion Tables
Convert measured variables to close
approximations of other characteristics of
the landscape. (Example diameter crown width
tables)
Statistical Analysis
Estimate a characteristic of the landscape seen
in a photo based on previous relationships
developed with field work.
Templates
Transparent overlays placed on a photo to assist
in measuring length, height, area, and
distance measurements.
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What is this?
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What is this?
Made by humans?
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What happened here?
1975
Very high altitude color-infrared Aerial
photography.
1992
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What are these?
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Why are the oak trees dense here?
What vegetation type is this?
FOR 220 Aerial Photo Interpretation and Forest
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