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