GEOGRAPHY 372 Lecture 1 – Introduction to Remote Sensing 26 January

Lab Meetings 2  Section to 11 am, Thursday  Section am to 1 pm, Thursday

Lab Meetings This Week 3  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 Textbook 4  Campbell, J.B., Introduction to Remote Sensing, 4th edition, The Gulford Press, 2007.

Class Web Page 5 All class materials will be placed on the Department of Geographies Courses Webpage: Click onto Academics/Course Information/ Course Materials/GEOG 372

Summary of Remote Sensing Courses in the Department of Geography 6 GEOG 372 – Introduction to Remote Sensing GEOG 472 – Principles of Remote Sensing GEOG671 – Remote sensing instrumentation and observing systems GEOG672 – Physical principles of remote sensing and land surface characterization Geog 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 Structure 8  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 Schedule 9  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 Exercises 10  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 Exercises 11  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 Material 12 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 Attend lectures and labs 2. Read assignment prior to class 3. During lectures, listen and synthesize information into key points 4. 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 Points Definition of remote sensing 2. Key elements of a remote sensing system 3. Definition of remote sensing (revisited) 4. Why remote sensing??? 5. Categories of remote sensors 6. Resolution and Remote Sensing 7. Key epochs or eras in remote sensing

Reading Assignment 16  Campbell, Chapter 1  Tatum, A.J., S.J. Goetz, and S.I. Hay, Fifty years of earth observation satellites, American Scientist 96: , 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 Points Definition of remote sensing 2. Key elements of a remote sensing system 3. Definition of remote sensing (revisited) 4. Why remote sensing??? 5. Categories of remote sensors 6. Resolution and Remote Sensing 7. Key epochs or eras in remote sensing

Elements of a Remote Sensing System 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 System 21 Sun Camera System

22 Balloon Photo of Boston ca. 1860s

Lecture 1 Outline/Key Points Definition of remote sensing 2. Key elements of a remote sensing system 3. Definition of remote sensing (revisited) 4. Why remote sensing??? 5. Categories of remote sensors 6. Resolution and Remote Sensing 7. 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 Points Definition of remote sensing 2. Key elements of a remote sensing system 3. Definition of remote sensing (revisited) 4. Why remote sensing??? 5. Categories of remote sensors 6. Resolution and Remote Sensing 7. Key epochs or eras in remote sensing

Why Remote Sensing? 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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29 Radar backscatter (image intensity) in burned forests is proportional to soil moisture

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31 MODIS Sea Surface Temperatures

Lecture 1 Outline/Key Points Definition of remote sensing 2. Key elements of a remote sensing system 3. Definition of remote sensing (revisited) 4. Why remote sensing??? 5. Categories of remote sensors 6. Resolution and Remote Sensing 7. Key epochs or eras in remote sensing

EM Spectrum Regions Used in Remote Sensing 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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Thermal IR Sensors 36  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

37 Figure 1-18 from Elachi, C., Introduction to the Physics and Techniques of Remote Sensing, 413 pp., John Wiley & Sons, New York, 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 39 Remote sensors are based on 1. Specific regions of the EM spectrum 2. The types of EM energy being detected 3. The source of EM energy, e.g., passive versus active sensors

Types of EM energy detected by remote sensors Reflected energy 1. Reflected EM energy Atmosphere 2. Emitted EM energy 3. Scattered EM energy Earth surface

Categories of Remote Sensors 41 Remote sensors are based on 1. Specific regions of the EM spectrum 2. The types of EM energy being detected 3. The source of EM energy, e.g., passive versus active sensors

Passive versus active systems 42  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

º K emitted 300º K emitted UV, Visible, Near IR Sensors Thermal IR, Microwave Sensors Active Sensors Microwave, Visible reflected emitted scattered

Lecture 1 Outline/Key Points Definition of remote sensing 2. Key elements of a remote sensing system 3. Definition of remote sensing (revisited) 4. Why remote sensing??? 5. Categories of remote sensors 6. Resolution and Remote Sensing 7. Key epochs or eras in remote sensing

Definition of resolution 45  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 Resolution 46  The measure of the smallest distance between objects that can be resolved by the sensor

47 Figure 1-8 from Jensen

Spectral Resolution 48  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 channels Each band has a center wavelength Each band has a width = spectral resolution Figure 9

Spectral Resolution 50  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 Resolution 51  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 Resolution 53  How often a remote sensor has the ability to record data over the same area.

Lecture 1 Outline/Key Points Definition of remote sensing 2. Key elements of a remote sensing system 3. Definition of remote sensing (revisited) 4. Why remote sensing??? 5. Categories of remote sensors 6. Resolution and Remote Sensing 7. Key epochs or eras in remote sensing

Key Milestones in Remote Sensing – Joseph Niepce takes first photograph 1858 – Gaspard Tournachon takes first aerial photograph from a balloon 1913 – First aerial photograph collected from an airplane 1942 – Kodak patents color infrared film 1950s, 60s – First airborne thermal scanner, multispectral scanner, high resolution synthetic aperture radar 1960s – 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 satellite 1980s – 2000s: Continued improvement in computer hardware and software - processing speed - storage capacity and data management 1990s – Development of the internet and world wide web 2000s – Routine production and delivery of information products derived from satellite images

Elements of a Remote Sensing System 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 Devices s1920s1950s Simple cameras Aerial cameras Electro – Optical & Microwave Systems

Remote Sensing Eras – Sensor Platforms s1910s1960s 2000s Balloons Aircraft Spacecraft UAV – Unmanned Aerial Vehicle

Remote Sensing Eras – Data recording and storage s 1960s/70s1990s 2000s Film BW/Color/ Color IR Digital Magnetic tape CD/DVD Mechanical Hard Drives Non- Mechanical Hard Drives

60 Standard for data storage until late 1980s – 9 track tape drive – Cost $50,000 1 tape = 2400 ft long Stored 50 Mb of information Cost 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 information s1970s Visual interpretation Optical analytical devices Computer aided digital analyses

Remote Sensing Eras – Delivery of information to the end user s 1970s 1990s 2000s Photographic products Hand-drawn products Computer generated products via digital tapes via the internet wiredwireless

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