introduction to remote sensingsite.iugaza.edu.ps/ajamassi/files/2010/02/lecture08.pdf · remote...

Introduction toIntroduction toRemote SensingRemote Sensing

OutlineOutline

Remote Sensing DefinedRemote Sensing Defined

ResolutionResolution

Electromagnetic Energy (EMR)Electromagnetic Energy (EMR)

TypesTypes

InterpretationInterpretation

ApplicationsApplications

Remote Sensing DefinedRemote Sensing Defined

Remote Sensing is:Remote Sensing is:

““The art and science of obtaining informationThe art and science of obtaining informationabout an object without being in direct contactabout an object without being in direct contactwith the objectwith the object”” (Jensen 2000).(Jensen 2000).

There is a medium of transmission involved.There is a medium of transmission involved.

Remote Sensing DefinedRemote Sensing Defined

Remote Sensing:Remote Sensing:

…… the collection of information about Earth surfacesthe collection of information about Earth surfacesand phenomena using sensors not in physical contactand phenomena using sensors not in physical contactwith the surfaces and phenomena of interest.with the surfaces and phenomena of interest.

We will focus on data collected from an overheadWe will focus on data collected from an overheadperspective via transmission of electromagneticperspective via transmission of electromagneticradiation.radiation.

Remote Sensing DefinedRemote Sensing Defined

Remote Sensing Includes:Remote Sensing Includes:

A) The mission plan and choice of sensors;A) The mission plan and choice of sensors;

B) The reception, recording, and processing of theB) The reception, recording, and processing of thesignal data; andsignal data; and

C) The analysis of the resultant data.C) The analysis of the resultant data.

Energy Source or Illumination (A)

Radiation and the Atmosphere (B)

Interaction with the Target (C)

Recording of Energy by the Sensor (D)

Transmission, Reception, andProcessing (E)

Interpretation and Analysis (F)

Application (G)

Remote Sensing Process Components

ResolutionResolution

AllAll remote sensing systems haveremote sensing systems have four typesfour types ofofresolution:resolution:

SpatialSpatial

SpectralSpectral

TemporalTemporal

RadiometricRadiometric

High vs. Low?

SpatialResolution

SpectralResolution

Temporal Resolution

Time

July 1 July 12 July 23 August 3

11 days

16 days

July 2 July 18 August 3

Radiometric Resolution

6-bit range0 63

8-bit range

0 255

0

10-bit range

1023

Electromagnetic RadiationElectromagnetic Radiation

Electromagnetic SpectrumElectromagnetic Spectrum

Signature SpectraSignature Spectra

Types of Remote SensingTypes of Remote Sensing

Aerial PhotographyAerial Photography

MultispectralMultispectral

Active and Passive Microwave and LIDARActive and Passive Microwave and LIDAR

Aerial PhotosAerial Photos

Balloon photographyBalloon photography(1858)(1858)

Pigeon camerasPigeon cameras(1903)(1903)

Kite photographyKite photography(1890)(1890)

Aircraft (WWI andAircraft (WWI andWWII)WWII)

Space (1947)Space (1947)

Images: Jensen (2000)

MultispectralMultispectral

NOAANOAA--AVHRR (1100 m)AVHRR (1100 m)

GOES (700 m)GOES (700 m)

MODIS (250, 500, 1000 m)MODIS (250, 500, 1000 m)

LandsatLandsat TM and ETM (30TM and ETM (30 –– 60 m)60 m)

SPOT (10SPOT (10 –– 20 m)20 m)

IKONOS (4, 1 m)IKONOS (4, 1 m)

QuickbirdQuickbird (0.6 m)(0.6 m)

AVHRR (Advanced Very HighAVHRR (Advanced Very HighResolution Radiometer) NASAResolution Radiometer) NASA

GOES (Geostationary OperationalGOES (Geostationary OperationalEnvironmental Satellites) IR 4Environmental Satellites) IR 4

MODIS (250 m)MODIS (250 m)

LandsatLandsat TMTM(False Color Composite)(False Color Composite)

SPOT (2.5 m)SPOT (2.5 m)

QUICKBIRD (0.6 m)QUICKBIRD (0.6 m)

IKONOS (4 mIKONOS (4 m MultispectralMultispectral))

IKONOS (1 m Panchromatic)IKONOS (1 m Panchromatic)

RADARRADAR(Radio Detection and Ranging)(Radio Detection and Ranging)

Image: NASA 2005

LIDARLIDAR(Light Detection and Ranging)(Light Detection and Ranging)

Elements of Image InterpretationElements of Image Interpretation

Shape:Shape:

Many natural and humanMany natural and human--made features havemade features haveunique shapes.unique shapes.

Often used are adjectives like linear,Often used are adjectives like linear,curvilinear, circular, elliptical, radial, square,curvilinear, circular, elliptical, radial, square,rectangular, triangular, hexagonal, star,rectangular, triangular, hexagonal, star,elongated, and amorphous.elongated, and amorphous.

Jensen (2000)

ShapeShape

Elements of Image InterpretationElements of Image Interpretation

Shadow:Shadow:

Shadow reduction is of concern in remote sensingShadow reduction is of concern in remote sensingbecause shadows tend to obscure objects thatbecause shadows tend to obscure objects thatmight otherwise be detected.might otherwise be detected.

However, the shadow cast by an object may beHowever, the shadow cast by an object may bethe only real clue to its identity.the only real clue to its identity.

Shadows can also provide information on theShadows can also provide information on theheight of an object either qualitatively orheight of an object either qualitatively orquantitatively.quantitatively.

Jensen (2000)

ShadowShadow

Elements of Image InterpretationElements of Image Interpretation

Tone and Color:Tone and Color: AA bandband of EMR recorded by a remote sensingof EMR recorded by a remote sensing

instrument can be displayed on an image ininstrument can be displayed on an image inshades of gray ranging from black to white.shades of gray ranging from black to white.

These shades are calledThese shades are called ““tonestones””, and can be, and can bequalitatively referred to as dark, light, orqualitatively referred to as dark, light, orintermediate (humans can see 40intermediate (humans can see 40--50 tones).50 tones).

Tone is related to the amount of light reflectedTone is related to the amount of light reflectedfrom the scene in a specific wavelength intervalfrom the scene in a specific wavelength interval(band).(band).

Jensen (2000)

Tone and ColorTone and Color

Elements of Image InterpretationElements of Image Interpretation

Texture:Texture:

Texture refers to the arrangement of tone or colorTexture refers to the arrangement of tone or colorin an image.in an image.

Useful because Earth features that exhibit similarUseful because Earth features that exhibit similartones often exhibit different textures.tones often exhibit different textures.

Adjectives include smooth (uniform,Adjectives include smooth (uniform,homogeneous), intermediate, and rough (coarse,homogeneous), intermediate, and rough (coarse,heterogeneous).heterogeneous).

Jensen (2000)

TextureTexture

Elements of Image InterpretationElements of Image Interpretation

Pattern:Pattern:

Pattern is the spatial arrangement of objects onPattern is the spatial arrangement of objects onthe landscape.the landscape.

General descriptions include random andGeneral descriptions include random andsystematic; natural and humansystematic; natural and human--made.made.

More specific descriptions include circular, oval,More specific descriptions include circular, oval,curvilinear, linear, radiating, rectangular, etc.curvilinear, linear, radiating, rectangular, etc.

Jensen (2000)

PatternPattern

Elements of Image InterpretationElements of Image Interpretation

Height and Depth:Height and Depth: As discussed, shadows can often offer clues to theAs discussed, shadows can often offer clues to the

height of objects.height of objects.

In turn, relative heights can be used to interpretIn turn, relative heights can be used to interpretobjects.objects.

In a similar fashion, relative depths can often beIn a similar fashion, relative depths can often beinterpreted.interpreted.

Descriptions include tall, intermediate, and short;Descriptions include tall, intermediate, and short;deep, intermediate, and shallow.deep, intermediate, and shallow.

Height and DepthHeight and Depth

Elements of Image InterpretationElements of Image Interpretation

Association:Association:

This isThis is veryvery important when trying toimportant when trying tointerpret an object or activity.interpret an object or activity.

AssociationAssociation refers to the fact that certainrefers to the fact that certainfeatures and activities are almost alwaysfeatures and activities are almost alwaysrelated to the presence of certain otherrelated to the presence of certain otherfeatures and activities.features and activities.

Jensen (2000)

AssociationAssociation

Imaging Tools and DataImaging Tools and Data

Google EarthGoogle Earth

ERDAS ImagineERDAS Imagine

Digital Northern GreatDigital Northern GreatPlainsPlains