INTRODUCTION TO REMOTE SENSING

BASIC PRINCIPLES OF REMOTE SENSING Definition of remote sensing  Remote sensing process  Data collection/acquisition  Data Requirement

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DEFINITION - 1 Remote sensing is the acquiring the data without touching it (Colwell, 1984)

DEFINITION - 2 Remote sensing is a non contact recording of information from the ultraviolet, visible, infrared, and microwave regions of the electromagnetic spectrum by means of instruments such as cameras, lasers, scanners, located on platforms such as air craft or space craft, and the analysis of the acquired information by means of visual and digital image processing.

(Fussel et al, 1982)

DEFINITION - 3 The science and arts of obtaining information about an object, area and phenomenon through the analysis of data collected by a device that is not in contact with the object, area or phenomenon under investigation.

(Lillesand & Kiefer, 2000)

DEFINITION Art - the process – aerial photos or image interpretation – combination of peoples knowledge, experience and skills - cannot be measured or programmed

Science – test fact and principles through scientific methods – include mathematics, logics, physics, social science, etc...

- use tools and technologies...

Introduction Remote sensing: 

A technology used for obtaining information about a target/object through the analysis of data acquired from the target/object at a distance.

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It is composed of 3 parts: –the targets - objects or phenomena in an area; –the data acquisition - through certain instruments; and –the data analysis - by some devices.

Information About The Target, Object Or Area sensors can obtained very specific information about an object (eg; diameter of tree) or geographic extent of phenomena (forest boundaries).  the electromagnetic energy emitted or reflected from an object to the sensors or instruments.  the electromagnetic energy measurement must be turned into information using visual or digital image processing techniques. 

The Instruments (Sensors) remote sensing is performed using instruments.  often refered as a sensors.  mostly record EMR that travels at a speed of light  there are a platform to place the sensors (aircraft, spacecraft, satellites, etc) 

Remote Sensing Process Element of Remote Sensing Process

Electromagnetic Radiation (EMR)  Atmosphere  Earth attributes/resources  Platforms/sensors  Data products  Interpretation and analysis 

Element of Remote Sensing Process 1. Electromagnetic Radiation (EMR) ď Ž the first requirement for remote sensing is to have an energy source which illuminates or provides electromagnetic energy to the target of interest 2. Atmosphere ď Ž as the energy travels from its source to the target, it will come in contact with and interact with the atmosphere it passes through. This interaction may take place a second time as the energy travels from the target to the sensor.

Element of Remote Sensing Process 3. Earth attributes/resources ď Ž once the energy makes its way to the target through the atmosphere, it interacts with the target depending on the properties of both the target and the radiation.

4. Platforms/sensors ď Ž after the energy has been scattered by, or emitted from the target, we require a sensor (remote - not in contact with the target) to collect and record the electromagnetic radiation.

Element of Remote Sensing Process 5. Data products ď Ž the energy recorded by the sensor has to be transmitted, often in electronic form, to a receiving and processing station where the data are processed into an image (hardcopy and/or digital).

6. Interpretation and analysis ď Ž the processed image is interpreted, visually and/or digitally or electronically, to extract information about the target which was illuminated. ď Ž the final element of the remote sensing process is achieved when we apply the information we have been able to extract from the imagery about the target in order to better understand it, reveal some new information, or assist in solving a particular problem.

An illustration of the remote sensing process is shown in Figure 1 and Figure 2 5. Data products

1. EMR

2. Atmosphere 4. Platforms/sensors

3. Earth attributes/resources

Figure 1

6. Interpretation and analysis

Figure 2

Lillesand & Kiefer, 2000

Data Collection/Acquisition 1. Platforms Types of platforms used in data acquisition • Aircraft • Satellites • Balloons • Rockets • space shuttles, etc

2. Sensors Sensors on-board the platforms are used to collect data include: aerial photographic cameras ď Ž non-photographic instruments, such as: - radiometers - electro-optical scanners - radar systems, etc ď Ž

Data Requirement Data collection may take place directly in the field (insitu data) or at some remote distance from the object or area of interest.

Remotely Sensed Data – data acquired without contact to the specific area of interest – Using specialized instruments – satellite, sensor, camera

Data Requirement Referenced Data  The acquisition of reference data include collecting measurements or observations about the objects, areas or phenomena.  The data may be needed for a particular analysis (soil types, survey data, ground thruth) In situ Data Collection  referred as field data  this data recorded and used to document and analyzed the primary data  use in situ measurement device at the study side to make the measurements. (e.g.: spectrometer)

Data Requirement 

Referenced and insitu data might be used to serve any or all the following purposes:– To aid in the analysis and interpretation of remotely sensed data.

– To calibrate a sensor.

– To verify the information extracted from remote sensing data.

SUCCESSFUL REMOTE SENSING APPLICATION Required components:  

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Clearly defined problems.

Evaluation of remotely sensed data as a suitable solution.

Identify required remotely sensed data.

Selection of appropriate processing methodology and reference data.

Establish criteria for error or accuracy assessment.

Major Application of Remote Sensing  Vegetations/Crops  Terrestrial (land use/land cover)  Oceanic (Surface/seafloor)  Disasters management  Geology and geomorphology  Environmental problems, etc

HISTORY OF REMOTE SENSING TECHNOLOGY

Aeronauts and Balloons:

The first known aerial The photograph was obtained in 1858 by photographer and aeronaut Gaspard Felix Tournachon.

The photograph was taken from a balloon suspended 265 ft above Paris

1 of the first cameras produced in France.

Jensen, 2000

The First Photograph

Jensen, 2000

The first photograph was obtained

by Joseph Nicephore Niepceof his French estate courtyard in 1827.

The earliest aerial photograph still in existence (and the first in the U.S.) was taken in 1860 by James W. Black and Samuel A. King .

It was taken from a balloon suspended 1,200 ft above Boston. .

Photography from Kites

Photography from Rockets

Pilot and aerial photographer with a Graflex aerial reconnaissance camera in 1915 (copyright Smithsonian Institution, Washington, D.C.).

Mangrove Map of Langkawi

Land use and land cover map

Before and After Landsat Imagery for the Mississippi Flood of 1997