Remote Sensing

By:-

Manish Solanki(13BCL109)

Rajan Sutariya(13BCL110)

Thakor Jitendra(13BCL111)

Abhisek Thayya(13BCL112)

Soham Trivedi(13BCL113)

Outline

1. Basic Concept2. Principles of radiation3. Types of system4. Spectral signatures5. Resolution7. Applications8.Adavantage

Remote sensing is the small- or large-scale acquisition of information of an object or phenomenon, by the use of either recording or real-time sensing device(s) that are wireless, or not in physical or intimate contact with the object (such as by way of aircraft, spacecraft, satellite)

In practice, remote sensing is the stand-off collection through the use of a variety of devices for gathering information on a given object or area.

Remote Sensing Systems:Remote Sensing Systems:the Human Eyethe Human Eye

• SpectralSpectral Resolution: 0.4-0.7 µm

• SpatialSpatial Resolution: ~ 1-3 cm @ 20 m

• RadiometricRadiometric Resolution: ~16-32 shades B/W or ~100 colors

Remote Sensing: A Definition

"Remote sensing is the science (and to some extent, art) of acquiring information about the Earth's surface without actually being in contact with it.”

This is done by sensing and recording reflected or emitted energy and processing, analyzing, and applying that information.

Satellite view of BCKVSatellite view of BCKV

Types of remote sensing

Passive: source of energy is either the Sun or Earth/atmosphere Sun

- wavelengths: 0.4-5 µm

Earth or its atmosphere- wavelengths: 3 µm -30 cm

Active: source of energy is part of the remote sensor system Radar

- wavelengths: mm-m Lidar

- wavelengths: UV, Visible, and near infrared

Camera takes photo as example, no flash and flash

Active sensors provide their own energy source for illumination.

Active Emit radiation

Radiation reflected is detected andmeasured

LIDAR, RADAR, and SONAR

Passive

Sun’s energy which is reflected (visible) or

Absorbed and re-emitted as thermal infrared wavelengths Landsat,AVHRR

Remote sensing systems which measure energy that is naturally available are called passive sensors

Passive remote sensing

Seven Elements of Remote SensingA. A.

Energy Energy Source or Source or IlluminationIllumination

For photography, the source is light from the sun. Other types of remote sensing, such as radar, supply their own energy source

Seven Elements of Remote Sensing

B. B.

Radiation & Radiation & AtmosphereAtmosphere

Remote sensing is affected by how well the illuminating energy penetrates the atmosphere. This is especially important when the distance involved is great, such as from a satellite

Seven Elements of Remote Sensing

C.C.

Interaction Interaction with Targetwith Target

What the remote sensor is really measuring is how the

energy interacts with the target.

Seven Elements of Remote Sensing

D. D.

Recording of Recording of Energy by the Energy by the SensorSensor

The sensor records the reflected energy it receives

Seven Elements of Remote Sensing

E. E. Transmission, Transmission, Reception, Reception, and and Processing Processing

All remote sensing systems have some method of transmitting, receiving, and processing the data. Some satellites actually drop film canisters to Earth using parachutes. Most remote sensing is now done digitally, and the data is transmitted using radio waves.

Seven Elements of Remote SensingF. F.

InterpretationInterpretation

andand

AnalysisAnalysis

Computers can do some analysis, but the final interpretation is up to the human element.

Seven Elements of Remote Sensing

G. G.

ApplicationApplication

Remotely sensed data isn’t much use unless it is gathered for a purpose or application.

A. Energy Source or IlluminationA. Energy Source or Illumination

Microwave region from about 1 mm to 1 m.

EMR

Modern physics acknowledges dual nature of EMR

The wave-particle duality refers to how EMR of differing wavelengths behaves, not what it is

Low frequency EMR tends to act more like a wave; higher frequency EMR tends to act more like a particle

The Nature of Light

In the 1860s, the Scottish mathematician and physicist James Clerk Maxwell succeeded in describing all the basic properties of electricity and magnetism in four equations

This mathematical achievement demonstrated that electric and magnetic forces are really two aspects of the same phenomenon, which we now call electromagnetism

Wave Model

Wavelength and frequency are related to the speed of light as follows: c = λv; λ = c/v; v = c/λ

•EMR travels as a set of sinusoidal orthogonal harmonic waves travelling at the speed of light, (c = 3.0x108ms-1)

Low frequency EMR tends to act more like a wave; higher frequency EMR tends to act more like a particle

Particle Model EMR is comprised of tiny particles (quanta) called

photons travelling in a wave-like pattern at the speed of light

Intensity is proportional to number of photons Total amount of energy is related to wavelength and

frequency by Planck’s constant (h):

Q = hv

Q = hc/λ

where : Q = energy of a quantum

The Foundation of RS

Differences in how features interact with and emit EMR allow us to distinguish between objects based on their unique spectral characteristics or signatures

Variations are wavelength dependant; some things may “look” the same at certain wavelengths but different in others

AdavantageRemote sensing makes it possible to collect data on dangerous or inaccessible areas andRemote sensing also replaces costly and slow data collection on the ground, ensuring in the process that areas or objects are not disturbed.Other uses include different areas of the earth sciences such as natural resource management, agricultural fields such as land usage and conservation.

All alone in our neighborhood of spaceAll alone in our neighborhood of space

Apollo 12’s Classic Earth Rise from Moon

Ikonos 1 m panchromatic imageryIkonos 1 m panchromatic imagery20002000

MODIS Land Reflectance and MODIS Land Reflectance and Sea Surface TemperatureSea Surface Temperature

Depending almost exclusively on imaging capabilities, "spy satellites" have activities. Visible, Near-Infrared; Thermal Infrared, and Radar sensors are applied to gathering been orbited by the hundreds (by several countries) to gather military intelligence or information about terrorist information about ground targets and activities of national security significance .

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TESAR IMAGE OF PENTAGON,U.S.A

Of course, picking up changes over large areas and long time spans is just one of many uses that space imagery is being put to. As an example here is a classification of major ground cover types in part of one county (Monmouth) in New Jersey just south of Sandy Hook. Its specific purpose was to define the surface characteristics that could affect water quality planning in the Navesink Watershed. This map was made using Landsat MSS imagery.

A given scene imaged at different times of the year can show great variety. Changing Sun angles, atmospheric variations, seasonal differences in vegetation cover, presence of snow, and other variables will produce often pronounced contrasts in the spectral responses that determine "how an image looks". This is evident in this montage of 6 Landsat MSS images of an area in the desert of Utah.

Here is a plot of the global distribution of the ionosphere, measured by the Jason-1 satellite (pages 8-7 and 14-12) whose prime mission is to measure Sea Surface Heights.

The image is made by HENA ( High Energy Neutron Atom ) sensor to show the density variations of hot plasma around the Earth .

This illustration is a two-dimensional cutaway sketch of streamlines representing solar wind particles as they passed through Earth's magnetic field.