Upload
peregrine-mitchell
View
215
Download
1
Tags:
Embed Size (px)
Citation preview
1
Lecture 4
Photographic Systems, Aerial Photography, and Image InterpretationFebruary 11th 2009
2
SyllabusLecture/Hourly Exam Schedule and Assigned Readings (Subject to Change)
Week Date Lecture Topic Reading Part I Remote Sensing Basics
1 26-Jan 1 Introduction to Remote Sensing Ch 1 28-Jan University Closed
2 02-Feb 2 Principles of EM radiometry and basic EM Theory Ch 204-Feb Principles of EM radiometry and basic EM Theory II
3 09-Feb 3 Atmospheric Influences on EM Radiation 11-Feb 4 Photographic Systems/Image Interpretation Ch 3,5
4 16-Feb 5 The Digital Image I Ch 4,1018-Feb The Digital Image II
5 23-Feb 6 Applications with areal and space photography 25-Feb Exam 126-FebLab 1 Introduction to ENVI – manipulation of digital imagery
3
Campbell, Chapters 3 (3.1-3.8) and 5 (5.1 to 5.11)
Unless otherwise noted, all images in this lecture are from Jensen, J.R., Remote Sensing of the
Environment - An Earth Resource Perspective, 544 pp., Prentice Hall, Upper Saddle River, NJ, 2000.
Reading Assignment
4
1. Components of a camera system2. Collection of aerial photographs 3. Categories of aerial photographs4. Photogrammetry5. Definition of image interpretation6. Reasons for using image interpretation7. Key elements of image interpretation
Lecture 4 Outline and Key Points
5Source of image from the internet
6
7
8
Joseph Niepce – 1826Created first photographic image in FranceUsed a camera obscura, exposed the scene for
8 hoursPhotographic plate was made of pewter and
was coated by bitumen suspended in lavender oil
Bitumen is a tar like substance found in crude oil – today it is used in roofing tar and asphalt pavement
When exposed to light, bitumen/oil hardened and adhered to the pewter plate
Non-hardened areas washed away
Early pioneers in photography
9
10
Emulsion layer
Base layer
Anti-halationlayer
Figure 5
11
Emulsion layers – contain light sensitive particles (silver-halide crystals) suspended in gelatin
Base or support material (polyester or cellulose acetate)
Anti-halation layer – absorbs all light that gets through first two layers to prevent reflection back into the emulsion
Film Layers
12
Based on three primary colors (red, green, blue)
When added together, these three primary colors produce white light
ACT is the basis for human vision and photographic systems
Additive Color Theory
13
Color films have 3 emulsion layers – filters are used to expose the emulsion layers to different regions of the EM spectrum
0.4 to 0.5 m: blue region of the EM spectrum
0.5 to 0.6 m: green region of the EM spectrum
0.6 to 0.7 m: red region of the EM spectrum
0.7 to 1.1 m: near infrared region of the EM spectrum
Photographic films
14
15
1. Components of a camera system2. Collection of aerial photographs 3. Categories of aerial photographs4. Photogrammetry5. Definition of image interpretation6. Reasons for using image interpretation7. Key elements of image interpretation
Lecture 4 Outline and Key Points
16
Aerial metric cameraFigure 6
17
Throughout most of the 20th century, aerial camera systems used film to record information
Aerial cameras used black and white, color and color-IR film to record data
This changed in 1986, when Kodak invented the first charged couple device that was capable of sensing and recording an entire photographic image The first digital camera recorded 1.4 million picture
elements (pixels) in a 5 by 7 inch format
Now, digital aerial camera systems are quite common
Invention of Digital Cameras
18Digital Aerial Camera System from Vexcel Corp.
19
Focal length (f) – is the distance, when the lens is focused on infinity from the center of the lens to the film or focal plane where the image is in focusWide angle lenses, have short focal lengthsTelescopic lenses have longer focal lengthsArea of coverage ~ 1 / f
Focal Length
20
One can alter the focal length
of the lenses used in a camera system to vary
the area of coverage of the
system
Figure 9
21
Relationship between aircraft altitudeand ground coverage – two ways to change FOV
a. Changing the focal length of the camera lens will alter the angular coverage of the system – as the focal length gets smaller, the angular coverage increases
b. As the angular cover increases (focal length decreases), the FOV increases
Figure 23
22
Relationship between aircraft altitudeand ground coverage – two ways to change FOV
Changing the aircraft altitude will alter the ground coverage of the system
23
1. Components of a camera system2. Collection of aerial photographs 3. Categories of aerial photographs4. Photogrammetry5. Definition of image interpretation6. Reasons for using image interpretation7. Key elements of image interpretation
Lecture 4 Outline and Key Points
24
25
26
27
Vertical Photograph Camera optical axis < 3° off vertical
Low-ObliqueCamera optical axis > 3° off verticalHorizon not in image
High ObliqueCamera optical axis > 3° off verticalHorizon in image
Categories of Aerial Photographs
28
SR-71World’sFastest Aerial Camera Platform
29
30
1. Components of a camera system2. Collection of aerial photographs 3. Categories of aerial photographs4. Photogrammetry5. Definition of image interpretation6. Reasons for using image interpretation7. Key elements of image interpretation
Lecture 4 Outline and Key Points
31
The science of making accurate measurements by means of aerial photographyRequires development of specific skills
What is Photogrammetry?
32
Analogue photogrammetryVisual interpretation using hard copy
(photographs or transparencies)
Digital or analytical photogrammetryComputer analysis on digitized photography
What is Photogrammetry?
33
1. Components of a camera system2. Collection of aerial photographs 3. Categories of aerial photographs4. Photogrammetry5. Definition of image interpretation6. Reasons for using image interpretation7. Key elements of image interpretation
Lecture 4 Outline and Key Points
34
The examination and analysis of images for the purpose of identifying objects and features and judging their importance
Image/Photo Interpretation
35
1. Components of a camera system2. Collection of aerial photographs 3. Categories of aerial photographs4. Photogrammetry5. Definition of image interpretation6. Reasons for using image interpretation7. Key elements of image interpretation
Lecture 4 Outline and Key Points
36
1. Represents the fundamental process for human (visual) analysis of remote sensing imagery
2. Provides a unique spatial observation perspective
3. Provides information that cannot easily be obtained in other ways
4. Provides ability to do accurate mapping, including 3-D information
5. Can provide information beyond our visual perception range
6. Allows for change detection analyses of specific regions where satellite data are not available
Why is image interpretation such an important tool?
37
38Image from -http://rs.gso.uri.edu/amy/avhrr.html
AVHRR Image of land and sea surface temperature from thermal IR radiance measurements
Red – warmestOrangeYellowGreenBlue Purple - coldest
39
1. Represents the fundamental process for human (visual) analysis of remote sensing imagery
2. Provides a unique spatial observation perspective
3. Provides information that cannot easily be obtained in other ways
4. Provides ability to do accurate mapping, including 3-D information
5. Can provide information beyond our visual perception range
6. Allows for change detection analyses of specific regions where satellite data are not available
Why is image interpretation such an important tool?
40
While human vision provides a unique perspective, it is a limited perspective
Humans primarily observe the world from a limited, ground-level view –vertical perspective
Aerial platforms allow the viewing of an area from a more synoptic, horizontal perspective
Unique perspective of aerial imagery – the aerial/regional perspective
41
42
43
1. Represents the fundamental process for human (visual) analysis of remote sensing imagery
2. Provides a unique spatial observation perspective
3. Provides information that cannot easily be obtained in other ways
4. Provides ability to do accurate mapping, including 3-D information
5. Can provide information beyond our visual perception range
6. Allows for change detection analyses of specific regions where satellite data are not available
Why is image interpretation such an important tool?
44
45Lillesand and Kiefer 2000Figure 4.32
46
1. Represents the fundamental process for human (visual) analysis of remote sensing imagery
2. Provides a unique spatial observation perspective
3. Provides information that cannot easily be obtained in other ways
4. Provides ability to do accurate mapping, including 3-D information
5. Can provide information beyond our visual perception range
6. Allows for change detection analyses of specific regions where satellite data are not available
Why is image interpretation such an important tool?
47
Can create a 3-D view using aerial photographs collected from slightly different vantage points
Using a stereoscope, allows an interpreter to view the earth’s surface in three dimensions
Extremely valuable for interpreting landforms and other 3-D features
Stereoscopic imagery can be processed to generate accurate 3-d maps (e.g., accurate in the x,y,z dimensions) of the earth’s surface
Stereoscopic viewing
48
1. Represents the fundamental process for human (visual) analysis of remote sensing imagery
2. Provides a unique spatial observation perspective
3. Provides information that cannot easily be obtained in other ways
4. Provides ability to do accurate mapping, including 3-D information
5. Can provide information beyond our visual perception range
6. Allows for change detection analyses of specific regions where satellite data are not available
Why is image interpretation such an important tool?
49
50
1. Represents the fundamental process for human (visual) analysis of remote sensing imagery
2. Provides a unique spatial observation perspective
3. Provides information that cannot easily be obtained in other ways
4. Provides ability to do accurate mapping, including 3-D information
5. Can provide information beyond our visual perception range
6. Allows for change detection analyses of specific regions where satellite data are not available
Why is image interpretation such an important tool?
51Lillesand and Kiefer 2000Figure 4.26
Monitoring Land Cover Change
1937
1955
1968
1990
52
1. Components of a camera system2. Collection of aerial photographs 3. Categories of aerial photographs4. Photogrammetry5. Definition of image interpretation6. Reasons for using image interpretation7. Key elements of image interpretation
Lecture 4 Outline and Key Points
53
Analysis of the cartographic information in the image
Examination of image characteristics
Key Steps in Image Interpretation
54
Analysis of image characteristicsSize (length, width, perimeter, area)ShapeShadowTone/colorPatternTextureSite/situation/association
Key Stepsin Image Interpretation
55
56
57
Shape
58
Shape
59
60
The presence of a shadow provides important information on the relative positions of objects
61
62Lillesand and Kiefer 2000Figure 4.41
63
1. Provide information on relative height2. Contain indirect information on geometric
characteristics of some features3. Provide a unique means for interpreting
topographic features4. Areas that are in shadows lack information
4 important aspects of shadows
64
BW photograph collected with Near infrared film
Image tone – variations in image tone (e.g., the grey scale from white to black) allow for discrimination of different forest cover types
Dark area is a pine stand and the light colored forests are deciduous trees
(see next slide)
65
Vegetation Reflectance
00.050.1
0.150.2
0.250.3
0.350.4
0.450.5
300 400 500 600 700 800 900 1000
Wavelength (nanometers)
Refle
ctance
Maple Pine
Blue Green Red
Infrared
Maple trees have a brighter tone
Pine trees have a darker tone
Reflectance controls image tone
66Shape & Tone
67
Texture – characteristic placement and arrangement of repetitions of tone and color in an image
Pattern – systematic or random arrangement of discrete objects within a scene
Texture and Pattern
68Texture & Pattern
69Texture & Pattern
70Texture & Pattern
71
Determining where an image was collected often provides key information on features within the image
Location provides context for interpreting an image
Importance of Location
72
73
1. Components of a camera system2. Collection of aerial photographs 3. Categories of aerial photographs4. Photogrammetry5. Definition of image interpretation6. Reasons for using image interpretation7. Key elements of image interpretation
Lecture 4 Outline and Key Points
74
SyllabusLecture/Hourly Exam Schedule and Assigned Readings (Subject to Change)
Week Date Lecture Topic Reading Part I Remote Sensing Basics
1 26-Jan 1 Introduction to Remote Sensing Ch 1 28-Jan University Closed
2 02-Feb 2 Principles of EM radiometry and basic EM Theory Ch 204-Feb Principles of EM radiometry and basic EM Theory II
3 09-Feb 3 Atmospheric Influences on EM Radiation 11-Feb 4 Photographic Systems/Image Interpretation Ch 3,5
4 16-Feb 5 The Digital Image I Ch 4,1018-Feb The Digital Image II
5 23-Feb 6 Applications with areal and space photography 25-Feb Exam 126-FebLab 1 Introduction to ENVI – manipulation of digital imagery