GEOGRAPHY 372
Lecture 1 – Introduction to Remote Sensing
26 January 2009
1
Lab Meetings2
Section 01019 to 11 am, Thursday
Section 010211 am to 1 pm, Thursday
Lab Meetings This Week3
Short meeting to review syllabus/policies etc., and also to tease out any technical difficulties. MANDATORY!!!
For those in Section 0101: We will meet this week from 10:00 – 11:00
For those in Section 0102: We will meet this week from 11:00 – 12:00
Course Textbook4
Campbell, J.B., Introduction to Remote Sensing, 4th edition, The Gulford Press, 2007.
Class Web Page5
All class materials will be placed on the Department of Geographies Courses Webpage:
http://www.geog.umd.edu/
Click onto Academics/Course Information/
Course Materials/GEOG 372
Summary of Remote Sensing Courses in the Department of Geography6
GEOG 372 – Introduction to Remote Sensing
GEOG 472 – Principles of Remote SensingGEOG671 – Remote sensing
instrumentation and observing systemsGEOG672 – Physical principles of remote
sensing and land surface characterizationGeog 788A – Seminar in Remote Sensing
Course Goals
7
Provide the student with a basic understanding of the science and technology of remote sensing of the environment
Provide a strong foundation for GEOG 472 Enable the student to understand the
differences between the various satellite remote sensing systems that are in existence today
Enable the student to differentiate between the different types of information products generated from data collected by these systems
Introduce students to the basics of digital image processing
Lecture Structure8
Part 1 – Remote Sensing Basics Part 2 – Remote Sensing in the Visible
and Near IR Region of the EM Spectrum Part 3 – Thermal and Microwave Remote
Sensing
Lab Schedule9
There will be 9-10 full labs throughout the course of the term
Each lab will last 2 hours The first full lab will be during week 4 or
5
Grading – Lab Exercises10
Each lab is worth an equal proportion of your grade, though the number of questions may not be equal.
Lab exercises turned in late will not receive full credit.
Late Lab Exercises11
Up to 4 days late – 80% maximum 5 to 7 days late – 50% maximum 8 to 14 days late – 20% maximum > 14 days late – 0 credit
Policy on Lecture Material12
At the end of each lecture, I will post a pdf file that contains
1. The figures, pictures, and tables used in that days lecture
2. A summary of the key points and concepts introduced during the lecture
Keys for success in GEOG 37213
1. Attend lectures and labs2. Read assignment prior to class3. During lectures, listen and synthesize
information into key points4. Review lecture materials and readings at the
end of each week: keep up and make sure you understand key points and concepts
5. Ask questions!!!6. Attend all labs and turn in assignments on time
Honor Code 14
The University has a nationally recognized Honor Code, administered by the Student Honor Council. The Student Honor Council proposed and the University Senate approved an Honor Pledge. The University of Maryland Honor Pledge reads:
"I pledge on my honor that I have not given or received any unauthorized assistance on this assignment/examination.“
This honor code must be handwritten and signed on all assignments and exams.
Lecture 1 Outline/Key Points15
1. Definition of remote sensing2. Key elements of a remote sensing
system3. Definition of remote sensing (revisited)4. Why remote sensing???5. Categories of remote sensors6. Resolution and Remote Sensing7. Key epochs or eras in remote sensing
Reading Assignment16
Campbell, Chapter 1 Tatum, A.J., S.J. Goetz, and S.I. Hay, Fifty
years of earth observation satellites, American Scientist 96:390-398, 2008.
What is Remote Sensing?17
Remote sensing uses the radiant energy that is reflected, emitted, or scattered from the Earth and its atmosphere from various portions (“wavelengths”) of the electromagnetic (EM) spectrum – referred to as electromagnetic radiation
Our eyes are only sensitive to the “visible light” portion of the EM spectrum
What is remote sensing?18
Definition 1 – Remote sensing is the acquiring of information about an object or scene without touching it through using electromagnetic energy
a. RS deals with systems whose data can be used to recreate images
b. RS deals with detection of the atmosphere, oceans, or land surface
Lecture 1 Outline/Key Points19
1. Definition of remote sensing2. Key elements of a remote sensing
system3. Definition of remote sensing (revisited)4. Why remote sensing???5. Categories of remote sensors6. Resolution and Remote Sensing7. Key epochs or eras in remote sensing
Elements of a Remote Sensing System20
2. Area or scene of interest
3. Sensing Device
4. Data Recorder
5. Information Production System
6. Information Delivery System
1. Information User
Basic Remote Sensing System21
Sun Camera System
22
Balloon Photo of Boston ca. 1860s
Lecture 1 Outline/Key Points23
1. Definition of remote sensing2. Key elements of a remote sensing
system3. Definition of remote sensing (revisited)4. Why remote sensing???5. Categories of remote sensors6. Resolution and Remote Sensing7. Key epochs or eras in remote sensing
What is remote sensing?24
Definition 2 – Remote sensing is the non-contact recording of information from the UV, visible, IR, and microwave regions of the EM spectrum by means of a variety of electro-optical systems, and the generation and delivery of information products based on the processing of these data
Lecture 1 Outline/Key Points25
1. Definition of remote sensing2. Key elements of a remote sensing
system3. Definition of remote sensing (revisited)4. Why remote sensing???5. Categories of remote sensors6. Resolution and Remote Sensing7. Key epochs or eras in remote sensing
Why Remote Sensing?
26 1. Electromagnetic energy being detected by remote sensors is dependent on the characteristic of the surface or atmosphere being sensed – Remote sensing provides unique information
2. Many portions of the earth’s surface and atmosphere are difficult to sample and measure using in situ measurements Only way to systematically collect data in
many regions
3. Remote sensors can continuously collect data Reliable and consistent source of information
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28
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Moderate Burn All Years
y = 0.3299x - 18.268
R2 = 0.82
-18
-16
-14
-12
-10
-8
-6
-4
-2
0
0 10 20 30 40 50
6 cm % Volumetric Moisture
ERS-2 Backscatter (dB)
All Years
2003-4 Validation Sites
Linear (All Years)
Radar backscatter (image intensity) in burned forests is proportional to soil moisture
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31MODIS Sea Surface Temperatures
Lecture 1 Outline/Key Points32
1. Definition of remote sensing2. Key elements of a remote sensing
system3. Definition of remote sensing (revisited)4. Why remote sensing???5. Categories of remote sensors6. Resolution and Remote Sensing7. Key epochs or eras in remote sensing
EM Spectrum Regions Used in Remote Sensing
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1. Ultraviolet ( < 0.4 m)2. Visible ( 0.4 m < < 0.7 m)3. Reflected IR ( 0.7 m < < 2.8 m)4. Emitted (thermal) IR ( 2.4 m < <
20 m)5. Microwave ( 1 cm < < 1 m)
= EM radiation wavelength
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35
Thermal IR Sensors36
Thermal IR deals with the Far IR region of the EM spectrum, wavelengths between 2.4 and 20 um
Most Thermal IR scanners use wavelengths between 8 and 15 um
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Figure 1-18 from Elachi, C., Introduction to the Physics and Techniques of Remote Sensing, 413 pp., John Wiley & Sons, New York, 1987.
Microwave remote sensing instruments operate at wavelengths greater than 1 mm
38
Radar systems operate in the microwave region of the EM
spectrum
Figure from Jensen
Categories of Remote Sensors
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Remote sensors are based on 1. Specific regions of the EM spectrum2. The types of EM energy being detected3. The source of EM energy, e.g., passive
versus active sensors
Types of EM energy detected by remote sensors
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1. Reflected energy1. Reflected EM energy
Atmosphere
2. Emitted EM energy
3. Scattered EM energy
Earth surface
Categories of Remote Sensors41
Remote sensors are based on 1. Specific regions of the EM spectrum2. The types of EM energy being detected3. The source of EM energy, e.g., passive
versus active sensors
Passive versus active systems42
Passive systems record energy that is emitted, scattered or reflected from natural sources, e.g., sunlight or emitted energy = f(the temperature of the surface or atmosphere being imaged)
Active systems provide their own source of EM radiation, which is then reflected or scattered, and this signal detected by the system
43
6000º Kemitted
300º K emitted
UV, Visible, Near IRSensors
Thermal IR, MicrowaveSensors
Active SensorsMicrowave, Visible
reflectedemitted
scattered
Lecture 1 Outline/Key Points44
1. Definition of remote sensing2. Key elements of a remote sensing
system3. Definition of remote sensing (revisited)4. Why remote sensing???5. Categories of remote sensors6. Resolution and Remote Sensing7. Key epochs or eras in remote sensing
Definition of resolution45
Also referred to as resolving power Defined as the ability of a remote sensor
to distinguish between signals that are spatially or spectrally similar
Four types of resolution important in remote sensing – spatial, spectral, radiometric, temporal
Spatial Resolution46
The measure of the smallest distance between objects that can be resolved by the sensor
47
Figure 1-8 from Jensen
Spectral Resolution48
Refers to the dimensions (widths) and wavelength regions of the EM spectrum to which a specific sensor is sensitive.
49
Spectral Bands in a Visible and Near IR Remote Sensor
Sensor has 6 different bands or channelsEach band has a center wavelengthEach band has a width = spectral resolution
Figure 9
Spectral Resolution50
Most remote sensing systems collect data in 1 to 10 different wavelength regions or bands, each with broad width. e.g. Landsat 7 ETM+ 7 bands
Hyperspectral remote sensing systems have a large number of very narrow bands. e.g. MODIS 36 Bands
Radiometric Resolution51
The sensitivity of a remote sensing detector to variations in the intensity of the emitted, reflected or scattered EM energy that is being detected, e.g., the precision of the system
52
One way to think of Radiometric Resolution
– how many different intensity levels can be discriminated by the remote sensor within a specific band?
Figure 10
Temporal Resolution53
How often a remote sensor has the ability to record data over the same area.
Lecture 1 Outline/Key Points54
1. Definition of remote sensing2. Key elements of a remote sensing
system3. Definition of remote sensing (revisited)4. Why remote sensing???5. Categories of remote sensors6. Resolution and Remote Sensing7. Key epochs or eras in remote sensing
Key Milestones in Remote Sensing
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1826 – Joseph Niepce takes first photograph1858 – Gaspard Tournachon takes first aerial photograph from a
balloon1913 – First aerial photograph collected from an airplane1942 – Kodak patents color infrared film1950s, 60s – First airborne thermal scanner, multispectral
scanner, high resolution synthetic aperture radar1960s – Corona satellite systems (cameras) initiated by the
Intelligence community , space photographs collected by astronauts
1960s, 1970s – Development of high speed computers and digital recording
1972 – ERTS-1 Launched – First Landsat satellite1980s – 2000s: Continued improvement in computer hardware
and software - processing speed - storage capacity and data management
1990s – Development of the internet and world wide web2000s – Routine production and delivery of information
products derived from satellite images
Elements of a Remote Sensing System56
2. Area or scene of interest
3. Sensing Device
4. Data Recorder
5. Information Production System
6. Information Delivery System
1. Information User
Remote Sensing Eras – Sensing Devices57
1830s 1920s 1950s
Simple camerasAerial cameras
Electro – Optical &
Microwave Systems
Remote Sensing Eras – Sensor Platforms58
1850s 1910s 1960s 2000s
Balloons
Aircraft
Spacecraft
UAV – UnmannedAerialVehicle
Remote Sensing Eras – Data recording and storage
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1830s 1960s/70s 1990s 2000sFilmBW/Color/Color IR
Digital Magnetic
tape
CD/DVD
MechanicalHard Drives Non-
MechanicalHardDrives
60
Standard for data storage until late 1980s – 9 track tape drive – Cost $50,000
1 tape = 2400 ft long
Stored 50 Mb of informationCost of storage continues to drop
2002 – 100 Gigabyte drive = $2000
Today – 100 Gigabyte drive = $< 200
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Remote Sensing Eras – Data processing and analysis – production of information62
1830s 1970sVisual interpretation
Optical analytical devices
Computer aided digital
analyses
Remote Sensing Eras – Delivery of information to the end user
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1830s 1970s 1990s 2000sPhotographic products
Hand-drawn products
Computer
generated products
via digital tapes via the
internet
wired wireless
For Next Lecture…64
We’ll continue with remote sensing related material, but also cover: Exams, including material covered, grading
and dates Overall course grading Lab meetings