1

GEOG 372

Lecture 1 – Introduction to Remote Sensing

2 September 2008

2

• Section 01019 to 12 am, Thursday

• Section 01029 to 12 am, Friday

3

Instructor - Dr. Eric S. Kasischke

Department of Geography

Room 1153 LeFrak Hall Telephone: 301 405 2179

E-mail: ekasisch@umd.edu

4

Eric S. KasischkeOffice Hours:

Tues/Thurs: 2 – 3 pmor by appointment

Do not hesitate to contact me for an appointment!!!!!

5

Laboratory Instructor

Alyssa Whitcraftalyssakw@umd.edu

 

6

Course Textbook

• Campbell, J.B., Introduction to Remote Sensing, 4th edition, The Gulford Press, 2007.

7

Class Web Page

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

8

Summary of Remote Sensing Courses

in the Department of Geography

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

9

Course Goals

• 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

10

Course Structure

• Two lectures per week are scheduled**– Readings assigned for most lectures

• One lab per week is scheduled**– Most labs will be written up and graded– Additional work outside of the lab will be

required to complete lab assignments

**see explanation in following slides

11

Lecture Schedule

• The course will have 17 lectures, each lasting 75 minutes

• Two lectures per week will be given for the first 4 weeks of class

• During the remainder of the course, there will be 1 lecture per week (on Tuesday only)

12

Lecture Structure

• 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

13

Lab Schedule

• There will be 9 full labs throughout the course of the term

• Each lab will last 3 hours• The first full lab will be during

week 5• Introductory labs on 4/5

September, 1030-1200

14

Evaluation of Students

• Hourly Exams (2 @ 19%) 38%• Final Exam 24%• Laboratory Assignments 28%• Pop quizzes (4) 10%

15

Evaluation of Students

• Test Grading Policy – One abnormally low score (out of three) will be partially discounted

• Course will be graded on a curve that roughly matches the GPA of the students

16

Exams

• Each exam will cover 1/3 of course material

• Final exam will also include material from entire course

• Only cover material presented in Lecture, but readings provide important supplemental material for student

17

Exam Dates

• Hourly Exam 1: 23 September

• Hourly Exam 2: 28 October• Final Exam: 19

December1:30 to 3:30

pm

18

Grading – Lab Exercises

• Each lab exercise is worth 10 points and is due at the beginning of the next lab period

• Lab exercises turned in late will not receive full credit

19

Late Lab Exercises

• Up to 4 days late – 8 points maximum• 5 to 7 days late – 6 points maximum• 8 to 11 days late – 4 points maximum• 12 to 14 days late – 2 points

maximum• > 14 days late – 0 points

20

Policy on Lecture Material

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

21

Keys for success in GEOG 372

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

22

Honor Code • 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.

23

Lecture 1 Outline/Key Points

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

24

Reading Assignment

• 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.

25

•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?

26

What is remote sensing?

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

27

Lecture 1 Outline/Key Points

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

28

Elements of a Remote Sensing System

2. Area or scene of interest

3. Sensing Device

4. Data Recorder

5. Information Production System

6. Information Delivery System

1. Information User

29

Basic Remote Sensing System

Sun Camera System

30

Balloon Photo of Boston ca.

1860s

31

Lecture 1 Outline/Key Points

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

32

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

What is remote sensing?

33

Lecture 1 Outline/Key Points

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

34

Why Remote Sensing?

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

35

36

37

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

ER

S-2

Bac

ksca

tter

(d

B)

All Years

2003-4 Validation Sites

Linear (All Years)

Radar backscatter (image intensity) in burned forests is proportional to soil moisture

38

39MODIS Sea Surface Temperatures

40

Lecture 1 Outline/Key Points

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

41

EM Spectrum Regions Used in Remote Sensing

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

42

43

44

Thermal IR Sensors

• 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

45

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

46

Radar systems operate in the microwave region of the EM

spectrum

Figure from Jensen

47

Categories of Remote Sensors

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

48

Types of EM energy detected by remote sensors

1. Reflected energy1. Reflected EM energy

Atmosphere

2. Emitted EM energy

3. Scattered EM energy

Earth surface

49

Categories of Remote Sensors

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

50

Passive versus active systems

• 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

51

6000º Kemitted

300º K emitted

UV, Visible, Near IRSensors

Thermal IR, MicrowaveSensors

Active SensorsMicrowave, Visible

reflectedemitted

scattered

52

Lecture 1 Outline/Key Points

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

53

Definition of resolution

• 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

54

Spatial Resolution

• The measure of the smallest distance between objects that can be resolved by the sensor

55

Figure 1-8 from Jensen

56

Spectral Resolution

• Refers to the dimensions (widths) and wavelength regions of the EM spectrum a specific sensor is sensitive to

57

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

58

Spectral Resolution

• Most remote sensing systems collect data in 1 to 10 different wavelength regions or bands, each with broad width

• Hyperspectral remote sensing systems have a large number of very narrow bands

59

Radiometric Resolution

• 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

60

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

61

Temporal Resolution

• How often a remote sensor has the ability to record data over the same area

62

Lecture 1 Outline/Key Points

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

63

Key Milestones in Remote Sensing

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

64

Elements of a Remote Sensing System

2. Area or scene of interest

3. Sensing Device

4. Data Recorder

5. Information Production System

6. Information Delivery System

1. Information User

65

Remote Sensing Eras – Sensing Devices

1830s 1920s 1950s

Simple camerasAerial cameras

Electro – Optical &

Microwave Systems

66

Remote Sensing Eras – Sensor Platforms

1850s 1910s 1960s 2000s

Balloons

Aircraft

SpacecraftUAV – UnmannedAerialVehicle

67

Remote Sensing Eras – Data recording and storage

1830s 1960s/70s 1990s 2000sFilmBW/Color/Color IR

Digital Magnetic

tape

CD/DVD

MechanicalHard Drives Non-

MechanicalHardDrives

68

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

69

70

Remote Sensing Eras – Data processing and analysis – production of information

1830s 1970sVisual interpretation

Optical analytical devices

Computer aided

digital analyses

71

Remote Sensing Eras – Delivery of information to the end user

1830s 1970s 1990s 2000sPhotographic productsHand-drawn products

Computer

generated products via digital tapes via the

internet

wired wireless