Remote Sensing and Digital Image Processing Remote Sensing and

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					  Remote Sensing and
  Remote Sensing and
Digital Image Processing
Digital Image Processing




    Introduction
                 In Situ Data Collection
                  In Situ Data Collection
Scientists formulate hypotheses and then attempt to
 Scientists formulate hypotheses and then attempt to
accept or reject them in a systematic, unbiased fashion.
 accept or reject them in a systematic, unbiased fashion.
The data necessary to accept or reject a hypothesis may
 The data necessary to accept or reject a hypothesis may
be collected directly in the field, often referred to as in
 be collected directly in the field, often referred to as in
situ or in-place data collection. This can be a time-
 situ or in-place data collection. This can be a time-
consuming, expensive, and inaccurate process.
 consuming, expensive, and inaccurate process.
Problems Associated with In Situ Data Collection
Problems Associated with In Situ Data Collection
Scientists can collect data in the field using biased
Scientists can collect data in the field using biased
procedures often referred to as method-produced error.
procedures often referred to as method-produced error.
Such error can be introduced by:
Such error can be introduced by:

 •• sampling design does not capture the spatial
     sampling design does not capture the spatial
      variability of the phenomena under investigation
       variability of the phenomena under investigation
      (i.e., some phenomena or geographic areas are
       (i.e., some phenomena or geographic areas are
      oversampled while others are undersampled);
       oversampled while others are undersampled);
 ••   improper operation of in situ measurement
       improper operation of in situ measurement
      instruments; or
       instruments; or
 ••   uncalibrated in situ measurement instruments.
       uncalibrated in situ measurement instruments.
                              In situ Measurement
                               In situ Measurement
                             In Support of Remote
                              In Support of Remote
                             Sensing Measurement
                              Sensing Measurement




In situ spectroradiometer
 In situ spectroradiometer   In situ ceptometer leaf-area-
                              In situ ceptometer leaf-area-
measurement of soybeans
measurement of soybeans       index (LAI) measurement
                               index (LAI) measurement
          Ground Reference Information
          Ground Reference Information

It is a misnomer to refer to in situ data as ground truth
 It is a misnomer to refer to in situ data as ground truth
data. Instead, we should refer to it simply as in situ
 data. Instead, we should refer to it simply as in situ
ground reference data, and acknowledge that it also
 ground reference data, and acknowledge that it also
contains error.
 contains error.
         Remote Sensing Data Collection
         Remote Sensing Data Collection
ASPRS adopted a combined formal definition of
ASPRS adopted a combined formal definition of
photogrammetry and remote sensing as (Colwell,
photogrammetry and remote sensing as (Colwell,
1997):
1997):
      “the art, science, and technology of obtaining
       “the art, science, and technology of obtaining
      reliable information about physical objects and
       reliable information about physical objects and
      the environment, through the process of
       the environment, through the process of
      recording, measuring and interpreting imagery
       recording, measuring and interpreting imagery
      and digital representations of energy patterns
       and digital representations of energy patterns
      derived from noncontact sensor systems”.
       derived from noncontact sensor systems”.
  A remote sensing instrument
    A remote sensing instrument
  collects information about an
   collects information about an
object or phenomenon within the
 object or phenomenon within the
    instantaneous-field-of-view
     instantaneous-field-of-view
   (IFOV) of the sensor system
    (IFOV) of the sensor system
 without being in direct physical
  without being in direct physical
  contact with it. The sensor is
    contact with it. The sensor is
       located on aasuborbital
        located on suborbital
         or satellite platform.
          or satellite platform.
         Observations About Remote Sensing
         Observations About Remote Sensing
Is Remote Sensing a Science?
 Is Remote Sensing a Science?
A science is defined as the broad field of human knowledge
 A science is defined as the broad field of human knowledge
concerned with facts held together by principles (rules).
 concerned with facts held together by principles (rules).
Scientists discover and test facts and principles by the scientific
 Scientists discover and test facts and principles by the scientific
method, an orderly system of solving problems. Scientists
 method, an orderly system of solving problems. Scientists
generally feel that any subject that humans can study by using
 generally feel that any subject that humans can study by using
the scientific method and other special rules of thinking may be
 the scientific method and other special rules of thinking may be
called aascience. The sciences include 1) mathematics and logic,
 called science. The sciences include 1) mathematics and logic,
2) the physical sciences, such as physics and chemistry, 3) the
 2) the physical sciences, such as physics and chemistry, 3) the
biological sciences, such as botany and zoology, and 4) the
 biological sciences, such as botany and zoology, and 4) the
social sciences, such as geography, sociology, and
 social sciences, such as geography, sociology, and
anthropology.
 anthropology.
  Interaction Model Depicting the Relationships of the Mapping Sciences as they
   Interaction Model Depicting the Relationships of the Mapping Sciences as they
 relate to Mathematics and Logic, and the Physical, Biological, nd Social Sciences
relate to Mathematics and Logic, and the Physical, Biological, aandSocial Sciences
       Observations About Remote Sensing
       Observations About Remote Sensing
Remote sensing is a tool or technique similar to
 Remote sensing is a tool or technique similar to
mathematics. Using sensors to measure the amount of
 mathematics. Using sensors to measure the amount of
electromagnetic radiation (EMR) exiting an object or
 electromagnetic radiation (EMR) exiting an object or
geographic area from a distance and then extracting
 geographic area from a distance and then extracting
valuable information from the data using
 valuable information from the data using
mathematically and statistically based algorithms is a
 mathematically and statistically based algorithms is a
scientific activity. It functions in harmony with other
 scientific activity. It functions in harmony with other
spatial data-collection techniques or tools of the
 spatial data-collection techniques or tools of the
mapping sciences, including cartography and
 mapping sciences, including cartography and
geographic information systems (GIS) (Clarke, 2001).
 geographic information systems (GIS) (Clarke, 2001).
        Observations About Remote Sensing
        Observations About Remote Sensing
Is Remote Sensing an Art?
 Is Remote Sensing an Art?
Visual image interpretation brings to bear not only scientific
 Visual image interpretation brings to bear not only scientific
knowledge but all of the experience that aaperson has obtained
 knowledge but all of the experience that person has obtained
in aalifetime. The synergism of combining scientific knowledge
 in lifetime. The synergism of combining scientific knowledge
with real-world analyst experience allows the interpreter to
 with real-world analyst experience allows the interpreter to
develop heuristic rules of thumb to extract information from the
 develop heuristic rules of thumb to extract information from the
imagery. Some image analysts are superior to other image
 imagery. Some image analysts are superior to other image
analysts because they 1) understand the scientific principles
 analysts because they 1) understand the scientific principles
better, 2) are more widely traveled and have seen many
 better, 2) are more widely traveled and have seen many
landscape objects and geographic areas, and/or 3) have the
 landscape objects and geographic areas, and/or 3) have the
ability to synthesize scientific principles and real-world
 ability to synthesize scientific principles and real-world
knowledge to reach logical and correct conclusions. Thus,
 knowledge to reach logical and correct conclusions. Thus,
remote sensing image interpretation is both an art and aascience.
 remote sensing image interpretation is both an art and science.
       Observations About Remote Sensing
       Observations About Remote Sensing
Information about an Object or Area
 Information about an Object or Area
Sensors can be used to obtain specific information
 Sensors can be used to obtain specific information
about an object (e.g., the diameter of a cottonwood tree
 about an object (e.g., the diameter of a cottonwood tree
crown) or the geographic extent of a phenomenon
 crown) or the geographic extent of a phenomenon
(e.g., the boundary of a cottonwood stand). The EMR
 (e.g., the boundary of a cottonwood stand). The EMR
reflected, emitted, or back-scattered from an object or
 reflected, emitted, or back-scattered from an object or
geographic area is used as a surrogate for the actual
 geographic area is used as a surrogate for the actual
property under investigation. The electromagnetic
 property under investigation. The electromagnetic
energy measurements must be calibrated and turned
 energy measurements must be calibrated and turned
into information using visual and/or digital image
 into information using visual and/or digital image
processing techniques.
 processing techniques.
             Advantages of Remote Sensing
             Advantages of Remote Sensing
••Remote sensing is unobtrusive if the sensor passively records
   Remote sensing is unobtrusive if the sensor passively records
the EMR reflected or emitted by the object of interest. Passive
 the EMR reflected or emitted by the object of interest. Passive
remote sensing does not disturb the object or area of interest.
 remote sensing does not disturb the object or area of interest.
••Remote sensing devices may be programmed to collect data
   Remote sensing devices may be programmed to collect data
systematically, such as within aa9  9 in. frame of vertical aerial
 systematically, such as within 9  9 in. frame of vertical aerial
photography. This systematic data collection can remove the
 photography. This systematic data collection can remove the
sampling bias introduced in some in situ investigations.
 sampling bias introduced in some in situ investigations.
••Under controlled conditions, remote sensing can provide
   Under controlled conditions, remote sensing can provide
fundamental biophysical information, including x,y location, zz
 fundamental biophysical information, including x,y location,
elevation or depth, biomass, temperature, and moisture content.
 elevation or depth, biomass, temperature, and moisture content.
            Advantages of Remote Sensing
            Advantages of Remote Sensing
••Remote sensing–derived information is now critical to the
  Remote sensing–derived information is now critical to the
successful modeling of numerous natural (e.g., water-supply
 successful modeling of numerous natural (e.g., water-supply
estimation; eutrophication studies; nonpoint source pollution)
 estimation; eutrophication studies; nonpoint source pollution)
and cultural (e.g., land-use conversion at the urban fringe;
 and cultural (e.g., land-use conversion at the urban fringe;
water-demand estimation; population estimation) processes
 water-demand estimation; population estimation) processes
(Walsh et al., 1999; Stow et al., 2003).
 (Walsh et al., 1999; Stow et al., 2003).
                                                 External
                                                  Forcing
                                                                                                              Remote
                                                                                                               Remote
                  Sun                                                          Volcanoes
                                                 Functions
                                                                                                           Sensing Earth
                                                                                                           Sensing Earth
                                                                                                          System Science
                                                                                                          System Science
                                  Stratospheric Chemistry and Dynamics


                                                Hydrologic               Biogeochemical Cycles
  Physical Climate System
                                                  Cycle

   Ocean                                                                                    Marine
  dynamics                                                                              biogeochemistry


Atmospheric                                    Global moisture
                                                                                          Tropospheric
 physics and
                                                                                           chemistry
  dynamics


 Terrestrial
                                                                                           Terrestrial
 energy and
                                                                                           ecosystems
  moisture
                                                Soil and water
                                                  chemistry



Climate
                                 Carbon Dioxide and Other Trace Gases
Change




               Water pollution                 Air pollution                 Land use


                                             Human Activities
            Limitations of Remote Sensing
            Limitations of Remote Sensing
••The greatest limitation is that it is often oversold. Remote
   The greatest limitation is that it is often oversold. Remote
sensing is not a panacea that provides all the information
 sensing is not a panacea that provides all the information
needed to conduct physical, biological, or social science
 needed to conduct physical, biological, or social science
research. It provides some spatial, spectral, and temporal
 research. It provides some spatial, spectral, and temporal
information of value in aamanner that we hope is efficient and
 information of value in manner that we hope is efficient and
economical.
 economical.
••Human beings select the appropriate remote sensing system to
   Human beings select the appropriate remote sensing system to
collect the data, specify the various resolutions of the remote
 collect the data, specify the various resolutions of the remote
sensor data, calibrate the sensor, select the platform that will
 sensor data, calibrate the sensor, select the platform that will
carry the sensor, determine when the data will be collected, and
 carry the sensor, determine when the data will be collected, and
specify how the data are processed. Human method-produced
 specify how the data are processed. Human method-produced
error may be introduced as the remote sensing instrument and
 error may be introduced as the remote sensing instrument and
mission parameters are specified.
 mission parameters are specified.
            Limitations of Remote Sensing
            Limitations of Remote Sensing
••Powerful active remote sensor systems that emit their own
   Powerful active remote sensor systems that emit their own
electromagnetic radiation (e.g., LIDAR, RADAR, SONAR) can
 electromagnetic radiation (e.g., LIDAR, RADAR, SONAR) can
be intrusive and affect the phenomenon being investigated.
 be intrusive and affect the phenomenon being investigated.
Additional research is required to determine how intrusive these
 Additional research is required to determine how intrusive these
active sensors can be.
 active sensors can be.
••Remote sensing instruments may become uncalibrated,
   Remote sensing instruments may become uncalibrated,
resulting in uncalibrated remote sensor data.
 resulting in uncalibrated remote sensor data.
••Remote sensor data may be expensive to collect and analyze.
   Remote sensor data may be expensive to collect and analyze.
Hopefully, the information extracted from the remote sensor
 Hopefully, the information extracted from the remote sensor
data justifies the expense.
 data justifies the expense.
           The Remote Sensing Process
           The Remote Sensing Process
The remote sensing data-collection and analysis
The remote sensing data-collection and analysis
procedures used for Earth resource applications are
procedures used for Earth resource applications are
often implemented in a systematic fashion referred to
often implemented in a systematic fashion referred to
as the remote sensing process.
as the remote sensing process.
              The Remote Sensing Process
              The Remote Sensing Process
••The hypothesis to be tested is defined using aaspecific type of
   The hypothesis to be tested is defined using specific type of
logic (e.g., inductive, deductive) and an appropriate processing
 logic (e.g., inductive, deductive) and an appropriate processing
model (e.g., deterministic, stochastic).
 model (e.g., deterministic, stochastic).
••In situ and collateral data necessary to calibrate the remote
   In situ and collateral data necessary to calibrate the remote
sensor data and/or judge its geometric, radiometric, and
 sensor data and/or judge its geometric, radiometric, and
thematic characteristics are collected.
 thematic characteristics are collected.
••Remote sensor data are collected passively or actively using
   Remote sensor data are collected passively or actively using
analog or digital remote sensing instruments, ideally at the same
 analog or digital remote sensing instruments, ideally at the same
time as the in situ data.
 time as the in situ data.
A Taxonomy of Models
 A Taxonomy of Models
used in Remote Sensing,
 used in Remote Sensing,
GIS, and Environmental
 GIS, and Environmental
    Science Research
     Science Research
             The Remote Sensing Process
             The Remote Sensing Process
••In situ and remotely sensed data are processed using a) analog
   In situ and remotely sensed data are processed using a) analog
image processing, b) digital image processing, c) modeling, and
 image processing, b) digital image processing, c) modeling, and
d) n-dimensional visualization.
 d) n-dimensional visualization.
••Metadata, processing lineage, and the accuracy of the
   Metadata, processing lineage, and the accuracy of the
information are provided and the results communicated using
 information are provided and the results communicated using
images, graphs, statistical tables, GIS databases, Spatial
 images, graphs, statistical tables, GIS databases, Spatial
Decision Support Systems (SDSS), etc.
 Decision Support Systems (SDSS), etc.
           Remote Sensing Data Collection
           Remote Sensing Data Collection
The amount of electromagnetic radiance, L (watts m-2 sr-1;;
 The amount of electromagnetic radiance, L (watts m-2 sr-1
watts per meter squared per steradian) recorded within the
 watts per meter squared per steradian) recorded within the
IFOV of an optical remote sensing system (e.g., aapicture
 IFOV of an optical remote sensing system (e.g., picture
element in aadigital image) is aafunction of:
 element in digital image) is function of:

                L  f  , s x , y , z , t ,  , P,  

where,
where,
 = wavelength (spectral response measured in various bands
  = wavelength (spectral response measured in various bands
 or at specific frequencies). Wavelength ) and frequency )
or at specific frequencies). Wavelength (()and frequency (()
may be used interchangeably based on their relationship with
 may be used interchangeably based on their relationship with
 the speed of light c) where
the speed of light ((c)where ..
           Remote Sensing Data Collection
           Remote Sensing Data Collection

 x,y,z = x, y, location of the picture element and its size x, )
ss = x, y, zzlocation of the picture element and its size ((x,yy)
  x,y,z

tt= temporal information, i.e., when and how often the
  = temporal information, i.e., when and how often the
information was acquired
 information was acquired

 = set of angles that describe the geometric relationships
  = set of angles that describe the geometric relationships
among the radiation source (e.g., the Sun), the terrain target of
 among the radiation source (e.g., the Sun), the terrain target of
interest (e.g., aacorn field), and the remote sensing system
 interest (e.g., corn field), and the remote sensing system

P = polarization of back-scattered energy recorded by the
 P = polarization of back-scattered energy recorded by the
sensor
 sensor

 = radiometric resolution (precision) at which the data (e.g.,
  = radiometric resolution (precision) at which the data (e.g.,
reflected, emitted, or back-scattered radiation) are recorded by
 reflected, emitted, or back-scattered radiation) are recorded by
the remote sensing system.
 the remote sensing system.
 Spectral
 Spectral
Resolution
Resolution
                         Airborne Visible
                          Airborne Visible
                         Infrared Imaging
                          Infrared Imaging
                           Spectrometer
                            Spectrometer
                       (AVIRIS) Datacube
                        (AVIRIS) Datacube
                       of Sullivan’s Island
                        of Sullivan’s Island
                            Obtained on
                            Obtained on
                         October 26, 1998
                          October 26, 1998



Color-infrared color
 composite on top
of the datacube was
created using three
 of the 224 bands
      at 10 nm
nominal bandwidth.
 Spatial
  Spatial
Resolution
Resolution
          Temporal Resolution
          Temporal Resolution


     Remote Sensor Data Acquisition
     Remote Sensor Data Acquisition
June 1, 2004
 June 1, 2004    June 17, 2004
                  June 17, 2004   July 3, 2004
                                   July 3, 2004



           16 days
            16 days
    Radiometric Resolution
    Radiometric Resolution

        -bit
      77-bit
0   (0 --127)
     (0 127)

            -bit
          88-bit
0       (0 --255)
         (0 255)

0                       -bit
                      99-bit
                    (0 --511)
                     (0 511)
                                  10-bit
                                   10-bit
0                               (0 --1023)
                                 (0 1023)
                    Angular Information
                    Angular Information
Remote sensing systems record very specific angular
 Remote sensing systems record very specific angular
characteristics associated with each exposed silver halide
 characteristics associated with each exposed silver halide
crystal or pixel. The angular characteristics are aafunction of:
 crystal or pixel. The angular characteristics are function of:
   ••location in aathree-dimensional sphere of the illumination
      location in three-dimensional sphere of the illumination
   source (e.g., the Sun for aapassive system or the sensor itself
    source (e.g., the Sun for passive system or the sensor itself
   in the case of RADAR, LIDAR, and SONAR) and its
    in the case of RADAR, LIDAR, and SONAR) and its
   associated azimuth and zenith angles,
    associated azimuth and zenith angles,
   ••orientation of the terrain facet (pixel) or terrain cover (e.g.,
      orientation of the terrain facet (pixel) or terrain cover (e.g.,
   vegetation) under investigation, and
    vegetation) under investigation, and
   ••location of the suborbital or orbital remote sensing system
      location of the suborbital or orbital remote sensing system
   and its associated azimuth and zenith angles.
    and its associated azimuth and zenith angles.
                   Angular Information
                   Angular Information
There is always an angle of incidence associated with the
 There is always an angle of incidence associated with the
incoming energy that illuminates the terrain and an angle of
 incoming energy that illuminates the terrain and an angle of
exitance from the terrain to the sensor system. This bidirectional
 exitance from the terrain to the sensor system. This bidirectional
nature of remote sensing data collection is known to influence
 nature of remote sensing data collection is known to influence
the spectral and polarization characteristics of the at-sensor
 the spectral and polarization characteristics of the at-sensor
radiance, L, recorded by the remote sensing system.
 radiance, L, recorded by the remote sensing system.
         Remote Sensing Data Analysis
         Remote Sensing Data Analysis
The analysis of remotely sensed data is performed using aa
 The analysis of remotely sensed data is performed using
variety of image processing techniques, including:
 variety of image processing techniques, including:
        ••analog (visual) image processing, and
           analog (visual) image processing, and
         ••digital image processing.
            digital image processing.
Analog and digital analysis of remotely sensed data seek to
 Analog and digital analysis of remotely sensed data seek to
detect and identify important phenomena in the scene. Once
 detect and identify important phenomena in the scene. Once
identified, the phenomena are usually measured, and the
 identified, the phenomena are usually measured, and the
information is used in solving problems. Optimum results are
 information is used in solving problems. Optimum results are
often achieved using aa synergistic combination of both visual
 often achieved using synergistic combination of both visual
and digital image processing.
 and digital image processing.
 Image
  Image
Analysis
Analysis
 Tasks
 Tasks
        Earth Resource Analysis Perspective
        Earth Resource Analysis Perspective
    Digital image processing is used for many applications,
     Digital image processing is used for many applications,
including: weapon guidance systems (e.g., the cruise missile),
 including: weapon guidance systems (e.g., the cruise missile),
 medical image analysis (e.g., -raying
medical image analysis (e.g., xx-raying aa broken arm),
                                                    broken arm),
nondestructive evaluation of machinery and products (e.g., on
 nondestructive evaluation of machinery and products (e.g., on
an assembly line), and analysis of Earth resources. This class
 an assembly line), and analysis of Earth resources. This class
focuses on the art and science of applying remote sensing
 focuses on the art and science of applying remote sensing
digital image processing for the extraction of useful Earth
 digital image processing for the extraction of useful Earth
resource information.
 resource information.
    Earth resource information is defined as any information
     Earth resource information is defined as any information
concerning terrestrial vegetation, soils, minerals, rocks, water,
 concerning terrestrial vegetation, soils, minerals, rocks, water,
certain atmospheric characteristics, and urban infrastructure.
 certain atmospheric characteristics, and urban infrastructure.
         Earth Resource Analysis Perspective
         Earth Resource Analysis Perspective
Such information may be useful for modeling:
 Such information may be useful for modeling:
••the global carbon cycle,
   the global carbon cycle,
••biology and biochemistry of ecosystems,
   biology and biochemistry of ecosystems,
••aspects of the global water and energy cycle,
   aspects of the global water and energy cycle,
••climate variability and prediction,
   climate variability and prediction,
••atmospheric chemistry,
   atmospheric chemistry,
••characteristics of the solid Earth,
   characteristics of the solid Earth,
••population estimation, and
   population estimation, and
••monitoring land-use change and natural hazards.
  monitoring land-use change and natural hazards.
  Digital
   Digital
  Image
   Image
Processing
Processing