Transcript
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GEOINFORMATICS(NCE 402)

By- Md Mozaffar Masud

Assistant Professor

Civil Engineering Department

JIT, Barabanki

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UNIT 1

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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.

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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

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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

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Scale of photographs

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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

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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)

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Types of vantage points to acquire photographs

Vertical vantage points

Low-oblique vantage points

High-oblique vantage points

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Vertical Aerial Photography

San Juan River

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Low-oblique Aerial Photography

Bridge on the Congaree river near Columbia

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High-oblique Aerial Photography

Grand Coulee Dam in Washington

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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)

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CIR and True Color Film Type Examples

CIR True Color

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CIR Films

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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

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Stereoscope

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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

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Photo interpretation: Recognition Elements

Shape

Size

Color/Tone

Texture

Pattern

Site

Association

Shadow

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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)

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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

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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

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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

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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

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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

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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

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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

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UNIT 2

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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.

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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

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Elements of RS

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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

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Remotely Sensed Data

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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.

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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

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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.

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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.

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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)

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Types of Resolution

Spatial resolution

Spectral Resolution

Radiometric Resolution

Temporal Resolution

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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

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Spatial resolution

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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

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Spectral Resolution

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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

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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

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Radiometric Resolution

6-bit range

0 63

8-bit range

0 255

0

10-bit range

2-bit range

0 4

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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.

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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

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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

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Normal color False-color infrared

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UNIT 3

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Satellite image

Satellite imagery

consists of photographs

from which collected by

satellites

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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

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Image HistogramsThe histogram ofan image shows usthe distribution ofgrey levels in theimage

Massively useful inimage processing,especially insegmentation

Grey Levels

Freq

ue

nci

es

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Histogram example

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Histogram example

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Histogram example contd.

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Histogram example contd.

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Histogram example contd.

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Histogram example contd.

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Histogram example contd.

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Histogram example contd.

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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

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Digital ImageA digital image isa representation ofa two-dimensionalimage as a finiteset of digitalvalues, calledpicture elementsor pixels

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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

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Image is not perfect sometime

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Image Enhancement

Spatial domain techniques

Point operations

Histogram equalization and matching

Applications of histogram-based enhancement

Frequency domain techniques

Unsharp masking

Homomorphic filtering

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Examples of Image Enhancement

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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

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LU and LC Classification System

general-purpose classification system

Land Utilization Survey

Land Use and Natural Resources Survey

Special Purpose Classification Systems

Wetlands Classification

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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.

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Application of RS

Urbanization & Transportation

Urban planning

Roads network and

transportation planning

City expansion

City boundaries by time

Wetland delineation

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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

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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

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UNIT 4

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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

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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.

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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

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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

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Arc Info

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Arc Info Contd.

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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

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Field Representation

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GIS as a data access mechanism

The geo library

place-based search

integrating information about a place

making access transparent

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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

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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.

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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.

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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.

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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

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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

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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

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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

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A six-way conceptual classification

Query and reasoning

Measurement

Transformation

Descriptive summary

Optimization

Hypothesis testing

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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

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Measurement

Area

Distance

Length

Perimeter

Slope, aspect

Shape

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Transformations

Buffering

Points in polygons

Polygon overlay

Spatial interpolation

Density estimation

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Descriptive summary

Centers

Measures of spatial dispersion

Spatial dependence

Fragmentation

Fractional dimension

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Optimization

Design to achieve specific objectives

Location of central point-like facilities to servedispersed demand

Location of linear facilities

Design of boundaries for elections

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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

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1990

1564

2886

995

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Application

Change Detection

Disaster Assessment

2004 Tsunami

Atmospheric Modeling

aerosols

air pollution

climate change

Ocean

topography

currents

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UNIT 5

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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

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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!

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Segments of GPS

Control Segment

Space Segment

User Segment

GroundAntennas

Master StationMonitor Station

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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

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GNSS Comparison

GLONASS

24 satellites (100% deployed)

3 orbital planes

GPS

31 satellites (>100% deployed)

6 orbital planes

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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

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Differential GPS

Real Time

Post Process

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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

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GPS Applications

Agriculture

Surveying

Navigation (air, sea, land)

Engineering

Military operations

Unmanned vehicle guidance

Mapping

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