geoinformatics(nce 402)
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GEOINFORMATICS(NCE 402)
By- Md Mozaffar Masud
Assistant Professor
Civil Engineering Department
JIT, Barabanki
UNIT 1
INTRODUCTION
Aerial photography is defined as art of takingphotograph from a point in the air for the purpose ofmaking study on earth surface.
Aerial photography and its planning includesselection of types of aero plane and camera, film andfilter combination which is of great importance inphoto interpretation.
Most of the conventional aerial photography is doneat 1:30000 to 1:60000 scale on a conventional blackand white panchromatic film.
INTRODUCTION
For more specific and detailed information such asground water surveys, land use planning , mineralexploration, photographs of scale 1:10000 to1:15000 are most suitable.
Quality of photographs depend upon-
flight and weather condition
Camera lens
Film and filters
Developing and printing processes
Basic Terminology
Focal Length – the distance between the camera lensand the film
Flying Height – the height of the plane (and thereforethe camera) above the ground
Nadir – the point on the ground directly below thecamera
Flight Line – the path of the airplane over which asequence of pictures is taken
Stereoscope - a device used to view/measure featureheights and/or landscape elevations using pairs of airphotographs
Fiducial Marks – marks on photographs used to alignadjacent photos for stereoscopic analysis
Scale of photographs
Air Photo Scale
Scale (RF) = [1 : (flying height / focal length)] or (focallength/flying height)
Focal length and flying height should be in the same units
Example:
Focal length = 6 inches or 0.5 ft
Flying height = 10,000 ft
Scale = 0.5 / 10,000 = 1:20,000
Basic Camera
Everything above “C” isinside the camera
The film sits on the filmplane
f = focal length
H = Elevation aboveground
ACB = angle of coverage
Scale: RF = 1:(H / f)
Types of vantage points to acquire photographs
Vertical vantage points
Low-oblique vantage points
High-oblique vantage points
Vertical Aerial Photography
San Juan River
Low-oblique Aerial Photography
Bridge on the Congaree river near Columbia
High-oblique Aerial Photography
Grand Coulee Dam in Washington
Types of film
Black and White
most often used in photogrammetry
cheap
Color
easy to interpret
fuzzy due to atmospheric scattering
Infrared
Color Infrared (CIR)
CIR and True Color Film Type Examples
CIR True Color
CIR Films
Stereoscopic Parallax
Stereoscopic Parallax iscaused by a shift in theposition of observation
Parallax is directly related tothe elevation / height offeatures
Vertical stereo pairs ofaerial photographs are usedto take 3-D measurementsby measuring parallax
Stereoscope
Sources of Distortion
From Collection: Yaw – plane fuselage not parallel to flight line
Think about having to steer your car slightly into a strong cross wind
Leads to pictures not being square with the flight-line Pitch – nose or tail higher than the other
Leads to principal point not being at nadir Roll – one wing higher than the other
Leads to principal point not being at nadir
Natural: Haze Topographic changes
For example, if flying over mountains, the height above the ground will a) change from picture to picture, and b) not be uniform in a single picture. Both of these lead to irregularities in the photo scale
Photo interpretation: Recognition Elements
Shape
Size
Color/Tone
Texture
Pattern
Site
Association
Shadow
Photo interpretation: Recognition Elements
Shape
cultural features - geometric, distinct boundaries
natural features - irregular shapes and boundaries
Shape helps us distinguish old vs. new subdivisions, some treespecies, athletic fields, etc.
The pentagon Meandering river in Alaska
Interior Alaskanvillage (note airstripnear top of image)
Size
relative size is an important clue
big, wide river vs. smaller river or
slough
apartments vs. houses
single lane road vs.
multilane
Photo interpretation: Recognition Elements
Photo interpretation: Recognition Elements
Color/Tone
coniferous vs. deciduous trees
CIR - Spruce forest (black) with some deciduous (red) trees.
CIR – Deciduous(leafy) vegetation(red).
CIR- Mixed spruce And deciduous foreston hillside with tundrain valley bottom
Photo interpretation: Recognition Elements
Texture
coarseness/smoothness caused by variability oruniformity of image tone or color
smoothness – tundra, swamps, fields, water, etc.
coarseness - forest, lava flows, mountains etc.
CIR- Marshy tundra with manysmall ponds
CIR - Bare roundedMountains (blue)surrounded by tundraand lakes
CIR - Tundra showing drainage pattern
Photo interpretation: Recognition Elements
Pattern overall spatial form ofrelated features repeating patterns tendto indicate culturalfeatures - random =natural drainage patterns canhelp geologists determinebedrock type
A dendritic pattern is characteristic of flat-lying sedimentary bedrock
Photo interpretation: Recognition Elements
Site
site - relationship of a feature toits environment
differences in vegetation basedon location:
In interior Alaska, blackspruce dominant on thenorth side of hills anddeciduous trees on the southside.
Vegetation is often hasdifferent characteristics byrivers than away from them
Meandering Alaskan river
Interior Alaskan hillside
Photo interpretation: Recognition Elements
Association
identifying one feature can help identify another -correlation
The white cloud andblack shadow have thesame shape, they arerelated
The long straight airstripnear the top of the imageindicates that there mightbe a village or settlementnearby
Photo interpretation: Recognition Elements
Shadows
shadows cast by somefeatures can aid intheir identification
some tree types,storage tanks, bridgescan be identified inthis way
shadows canaccentuate terrain The mountain ridge on
the right side of this imageis accentuated by shadow
UNIT 2
What is remote sensing used for What
is reRemote Sensingmote sensing used
for What is remote sensing used forDefinitions:
The acquisition of physical data of an objectwithout touch or contact .
The observation of a target by a device somedistance away.
The use of electromagnetic radiation sensors torecord images of the environment, which can beinterpreted to yield useful information.
Advantages of RS
Provides a view for the large region
Offers Geo-referenced information and digitalinformation
Most of the remote sensors operate in every season,every day, every time and even in real tough weather.
Remote sensing can be either passive or active.Active systems have their own source of energywhereas the passive systems depend upon the solarillumination or self emission for remote sensing
Elements of RS
Process of RS Data
Emission of electromagnetic radiation, or EMR (sun/self-emission)
Transmission of energy from the source to the surface ofthe earth, as well as absorption and scattering
Interaction of EMR with the earth's surface: reflectionand emission
Transmission of energy from the surface to the remotesensor
Sensor data output
Data transmission, processing and analysis
Remotely Sensed Data
Remote Sensing Satellite
Polar-Orbiting Satellites
A polar orbit is a
satellite which is
located near to above of
poles. This satellite
mostly uses for earth
observation by time.
Remote Sensing Satellite
Geostationary Satellites
A geostationary satellite
is one of the satellites
which is getting remote
sense data and
located satellite at an
altitude of approximately
36000 kilometres and
directly over the equator
Remote Sensing Sensors
Sensor is a device that gathers energy (EMR orother), converts it into a signal and presents it in aform suitable for obtaining information about thetarget under investigation. These may be active orpassive depending on the source of energy .
Sensors used for remote sensing can be broadlyclassified as those operating in Optical Infrared (OIR)region and those operating in the microwave region.OIR and microwave sensors can further besubdivided into passive and active.
Active sensors use their own source of energy. Earthsurface is illuminated through energy emitted by its ownsource, a part of its reflected by the surface in thedirection of the sensor is received to gather information.
Passive sensors receive solar electromagnetic energyreflected from the surface or energy emitted by thesurface itself. These sensors do not have their ownsource of energy and can not be used at night time,except thermal sensors. Again, sensors (active orpassive) could either be imaging, like camera, or Sensorwhich acquire images of the area and non-imaging typeslike non-scanning radiometer or atmospheric sounders.
Resolution
Resolution is defined as the ability of the system torender the information at the smallest discretelyseparable quantity in terms of distance (spatial),wavelength band of EMR (spectral), time (temporal)and/or radiation quantity (radiometric)
Types of Resolution
Spatial resolution
Spectral Resolution
Radiometric Resolution
Temporal Resolution
Spatial resolution—
The earth surface area covered by a pixel of animage is known as spatial resolution
Large area covered by a pixel means low spatialresolution and vice versa
Spatial resolution
Spectral Resolution –
Is the ability to resolve spectral features andbands into their separate components
More number of bands in a specified bandwidthmeans higher spectral resolution and vice versa
Spectral Resolution
Spectral Resolution
Three spectra recorded at low, medium and high spectralresolution, illustrating how the high resolution mode yieldssharper peaks, and separates close lying peaks, which aremerged together at low resolution
Radiometric Resolution -
Sensitivity of the sensor to the magnitude of thereceived electromagnetic energy determines theradiometric resolution
Finer the radiometric resolution of a sensor, if it ismore sensitive in detecting small differences inreflected or emitted energy
Radiometric Resolution
6-bit range
0 63
8-bit range
0 255
0
10-bit range
2-bit range
0 4
Temporal Resolution-
Frequency at which images are recorded/captured in a specific place on the earth.
The more frequently it is captured, the better orfiner the temporal resolution is said to be
For example, a sensor that captures an image ofan agriculture land twice a day has bettertemporal resolution than a sensor that onlycaptures that same image once a week.
Temporal Resolution-
Remote Sensing & GIS Applications Directorate
Time
July 1 July 12 July 23 August 3
11 days
16 days
July 2 July 18 August 3
Color Science
Additive primary colors : Blue, Green, and Red
Subtractive primary colors (orcomplementary colors): Yellow, Magenta, and Cyan
Filters (subtract or absorb some colorsbefore the light reaches the camera): Red filter (absorbs green and blue, you can
see red)
Yellow (or minus-blue) filter (absorbs blue,allows green and red to be transmitted,which is yellow)
Haze filter (absorbs UV)
additive
Subtractive
Normal color False-color infrared
UNIT 3
Satellite image
Satellite imagery
consists of photographs
from which collected by
satellites
Global overview
What does satellite imagery give you?
Information on land cover, land use, habitats, landscape and
infrastructure
multiple engagements by time series
Mapping and monitoring changes and predict future
Image HistogramsThe histogram ofan image shows usthe distribution ofgrey levels in theimage
Massively useful inimage processing,especially insegmentation
Grey Levels
Freq
ue
nci
es
Histogram example
Histogram example
Histogram example contd.
Histogram example contd.
Histogram example contd.
Histogram example contd.
Histogram example contd.
Histogram example contd.
Histogram example contd.
A selection of images andtheir histograms
Notice the relationshipsbetween the images andtheir histograms
Note that the high contrastimage has the mostevenly spaced histogram
Digital ImageA digital image isa representation ofa two-dimensionalimage as a finiteset of digitalvalues, calledpicture elementsor pixels
Digital Image contd.
Pixel values typically represent gray levels, colours,heights, opacities etc
Remember digitization implies that a digital image isan approximation of a real scene
1 pixel
Image is not perfect sometime
Image Enhancement
Spatial domain techniques
Point operations
Histogram equalization and matching
Applications of histogram-based enhancement
Frequency domain techniques
Unsharp masking
Homomorphic filtering
Examples of Image Enhancement
Land use and Land cover
Land use – defined by economic terms
Land cover – visible features
Both are important and are really inseparable
We depend on accurate LU/LC data for scientific andadministrative purposes
LU and LC Classification System
general-purpose classification system
Land Utilization Survey
Land Use and Natural Resources Survey
Special Purpose Classification Systems
Wetlands Classification
Unsupervised and Supervised Classification
Supervised learning: discover patterns in the datathat relate data attributes with a target (class)attribute.
These patterns are then utilized to predict thevalues of the target attribute in future datainstances.
Unsupervised learning: The data have no targetattribute.
We want to explore the data to find some intrinsicstructures in them.
Application of RS
Urbanization & Transportation
Urban planning
Roads network and
transportation planning
City expansion
City boundaries by time
Wetland delineation
Application of RS
Agriculture
The application of remote sensing in
agriculture include:
-Soil sensing
-Farm classification
- Farm condition assessment
- Agriculture estimation
- Mapping of farm and agricultural
land characteristics
- Mapping of land management
practices
- Compliance monitoring
Application of RS
Monitoring dynamic changes
Urban/Rural infrastructure
Water logging & salinity
Assessment of spatial
distribution of land resources
Infrastructure monitoring
Availability of usable land
Future planning for better land
management for socio-
economic development
Land use/ land cover mapping
UNIT 4
GIS BasicGeographic Information System
Allows the viewing and analysis of multiplelayers of spatially related informationassociated with a geographic region/location
The widespread collection and integration ofimagery into GIS has been made possiblethrough remote sensing
With the increasing technologicaldevelopment of remote sensing, thedevelopment of GIS has simultaneouslyaccelerated
Introduction contd.
A system to present information and analysis thathas a geographic component.
A system that uses maps and images to track anysort of information.
Both spatial and attribute (tabular) data areintegrated.
The GIS data types
Discrete geographic features
points, lines, areas
the contents of maps
with associated attributes
countable
conceived as tables with associated featuregeometry
ESRI shape files
GIS Fields
Geography as a collection of continuous variables
measured on nominal, ordinal, interval, ratioscales
vector fields of direction and magnitude
exactly one value per point
z=f(x)
population density, land ownership, zoning
Arc Info
Arc Info Contd.
Field representations
Raster of rectangular cells
Raster of uniformly spaced points
Irregularly spaced points
Irregular areas (polygons)
Digitized contours
Triangular mesh (triangulated irregular network orTIN)
ESRI coverages
Field Representation
GIS as a data access mechanism
The geo library
place-based search
integrating information about a place
making access transparent
Types of GIS
There are a number of Geographical Information Systems(GIS) (or GIS software) available today. They range from high-powered analytical software to visual web applications, andeach of those are used for a different purpose.Due to the vast number of GIS available it is simply notpossible to provide training for each in this course. However,there are common feature in all GIS. Understanding thesebasic features will give you confidence with any GIS systemthat you use in the future. This course will cover three groups of GIS:
Web-based GIS: ONS and London Profiler Geobrowser: Google Earth Desktop GIS: Arc GIS
Web-based GIS
Web-based GIS, or WebGIS, are online GISapplications which in most cases are excellent datavisualisation tools. Their functionality is limitedcompared to software stored on your computer, butthey are user-friendly and particularly useful asthey not required data download.
There are many WebGIS available, but in thiscourse we will use two of them: the Office ofNational Statistics (ONS) Neighbourhood mappingtool and the London Profiler.
Geobrowser
A Geobrowser is better explained with reference toan internet browser, i.e. Internet Explorer. In short, ageobrowser can be understood as an Internet Explorerfor geographic information. Like the internet it allowsthe combination of many types of geographic data frommany different sources. The biggest difference betweenthe World Wide Web and the geographic web howeveris that everything within the latter is spatiallyreferenced.
Google Earth is the most popular geobrowseravailable and will be the one used for this course.
Desktop GIS
A GIS, or GIS software, allows you to interactivelywork with spatial data. A desktop GIS is a mappingsoftware that needs to be installed onto and runs on apersonal computer.
In this course, we will use ArcGIS, which is developedby ESRI. ArcGIS is what ESRI refer to as a suite ofproducts which can be tailored to your need. ArcGIS isused for a vast range of activities, covering bothcommercial and educational uses.
The basic version of ArcGIS is what we will be using inthis course and is all the majority of GIS users will everneed.
Spatial Data
Spatial data
information about phenomena organized in aspatial frame
the geographic frame
Methods applied to spatial data that
add value
reveal patterns and anomalies
support decisions
Spatial Analysis
Methods whose results depend on the locations ofphenomena in the frame
are not invariant under relocation
Some types of relocation may not affect socialprocesses
rotation
relocation
inversion
Spatial analysis as a collaboration
The computer as butler to the human mind
Are maps “mere”?
Humans as sources of context
cross-sectional data are already rich in context
Taxonomies of spatial analysis
Thousands of methods
every one a command, menu item, icon, …
Based on data type
point pattern analysis
area (polygon) analysis
analysis of interactions
A six-way conceptual classification
Query and reasoning
Measurement
Transformation
Descriptive summary
Optimization
Hypothesis testing
Query and reasoning
Real-time answers to geographic questions
Where is…?
What is this?
How do I get from here to here?
Based on alternative views of a database
Measurement
Area
Distance
Length
Perimeter
Slope, aspect
Shape
Transformations
Buffering
Points in polygons
Polygon overlay
Spatial interpolation
Density estimation
Descriptive summary
Centers
Measures of spatial dispersion
Spatial dependence
Fragmentation
Fractional dimension
Optimization
Design to achieve specific objectives
Location of central point-like facilities to servedispersed demand
Location of linear facilities
Design of boundaries for elections
Hypothesis testing
Geographic objects as a sample from a population
what is the population?
The independence assumption
the First Law of Geography
failure to find spatial dependence is always a TypeII error
hell is a place with no spatial dependence
1990
1564
2886
995
Application
Change Detection
Disaster Assessment
2004 Tsunami
Atmospheric Modeling
aerosols
air pollution
climate change
Ocean
topography
currents
UNIT 5
GPS
Stands for Global Positioning System
GPS is used to get an exact location on or above the
surface of the earth (1cm to 100m accuracy).
Developed by DoD (Department of Defense, U.S.)
and made available to public in 1983.
GPS is a very important data input source.
GPS is one of two (soon to be more) GNSS – Global
Navigation Satellite System
GNSS
NAVSTAR – U.S. DoD (“GPS”)
GLONASS – Russian system
Galileo – European system (online in 2019?)
Compass/BeiDou-2 – Chinese system in
development (operational with 10 satellites as of
December, 2011; 35 planned)
GPS and GLONASS are free to use!
Segments of GPS
Control Segment
Space Segment
User Segment
GroundAntennas
Master StationMonitor Station
Data Models
Raster Model
The first GIS model developed
Based on grids of cells that are assigned valuesand grouped into layers
Vector Model
Uses points, lines, and polygons define dataclasses
Grouped into themes
GNSS Comparison
GLONASS
24 satellites (100% deployed)
3 orbital planes
GPS
31 satellites (>100% deployed)
6 orbital planes
System Components
Receiver
Receives satellite signals
Compiles location info, ephemeris info, clockcalibration, constellation configuration (PDOP)
Calculates position, velocity, heading, etc…
Data Collector
Stores positions (x,y,z,t)
Attribute data tagged to position
Software
Facilitates file transfer to PC and back
Performs differential correction (post-processing)
Displays data and
Differential GPS
Real Time
Post Process
GPS Applications
GPS uses into five categories
Location – positioning things in space
Navigation – getting from point a to point b
Tracking - monitoring movements
Mapping– creating maps based on those positions
Timing – precision global timing
GPS Applications
Agriculture
Surveying
Navigation (air, sea, land)
Engineering
Military operations
Unmanned vehicle guidance
Mapping
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