Gis Geographical Information System FundamentalsUroosa Samman
Gis, Geographical Information System Fundamentals. This presentation includes a complete detail of GIS and GIS Softwares. It will help students of GIS and Environmental Science.
DEFINITION :
GIS is a powerful set of tools for collecting, storing , retrieving at will, transforming and displaying spatial data from the real world for a particular set of purposes
APPLICATION AREAS OF GIS
Agriculture
Business
Electric/Gas utilities
Environment
Forestry
Geology
Hydrology
Land-use planning
Local government
Mapping
11. Military
12. Risk management
13. Site planning
14. Transportation
15. Water / Waste water industry
COMPONENTS OF GIS
DATA INPUT
SPATIAL DATA MODEL
Data Model:
It describes in an abstract way how the data is represented in an information system or in DBMS
Spatial Data Model :
The models or abstractions of reality that are intended to have some similarity with selected aspects of the real world
Creation of analogue and digital spatial data sets involves seven levels of model development and abstraction
SPATIAL DATA MODEL
Conceptual model : A view of reality
Analog model : Human conceptualization leads to analogue abstraction
Spatial data models : Formalization of analogue abstractions without any conventions
Database model : How the data are recorded in the computer
Physical computational model : Particular representation of the data structures in computer memory
Data manipulation model : Accepted axioms and rules for handling the data
SPATIAL DATA MODEL
SPATIAL DATA MODEL
Objects on the earth surface are shown as continuous and discrete objects in spatial data models
Types of data models
Raster data model
vector data models
RASTER DATA MODEL
Basic Elements :
Extent
Rows
Columns
Origin
Orientation
Resolution: pixel = grain = grid cell
Ex: Bit Map Image (BMP),Joint Photographic Expert Group (JPEG), Portable Network Graphics(PNG) etc
RASTER DATA MODEL
VECTOR DATA MODEL
Basic Elements:
Location (x,y) or (x,y,z)
Explicit, i.e. pegged to a coordinate system
Different coordinate system (and precision) require different values
o e.g. UTM as integer (but large)
o Lat, long as two floating point numbers +/-
Points are used to build more complex features
Ex: Auto CAD Drawing File(DWG), Data Interchange(exchange) File(DXF), Vector Product Format (VPF) etc
VECTOR DATA MODEL
RASTER vs VECTORRaster is faster but Vector is corrector
TESSELLATIONS OF CONTINUOUS FIELDS
Triangular Irregular Network: (TIN)
TIN is a vector data structure for representing geographical information that is continuous
Digital elevation model
TIN is generally used to create Digital Elevation Model (DEM)
DIGITAL ELEVATION MODEL
DATA STRUCTURES
Data structure tells about how the data is stored
Data organization in raster data structures
Each cell is referenced directly
Each overlay Is referenced directly
Each mapping unit is referenced directly
Each overlay is separate file with general header
This presentation is about the raster and vector data in GIS which is important and costly as well, through the presentation we will learn about both type of data.
Gis Geographical Information System FundamentalsUroosa Samman
Gis, Geographical Information System Fundamentals. This presentation includes a complete detail of GIS and GIS Softwares. It will help students of GIS and Environmental Science.
DEFINITION :
GIS is a powerful set of tools for collecting, storing , retrieving at will, transforming and displaying spatial data from the real world for a particular set of purposes
APPLICATION AREAS OF GIS
Agriculture
Business
Electric/Gas utilities
Environment
Forestry
Geology
Hydrology
Land-use planning
Local government
Mapping
11. Military
12. Risk management
13. Site planning
14. Transportation
15. Water / Waste water industry
COMPONENTS OF GIS
DATA INPUT
SPATIAL DATA MODEL
Data Model:
It describes in an abstract way how the data is represented in an information system or in DBMS
Spatial Data Model :
The models or abstractions of reality that are intended to have some similarity with selected aspects of the real world
Creation of analogue and digital spatial data sets involves seven levels of model development and abstraction
SPATIAL DATA MODEL
Conceptual model : A view of reality
Analog model : Human conceptualization leads to analogue abstraction
Spatial data models : Formalization of analogue abstractions without any conventions
Database model : How the data are recorded in the computer
Physical computational model : Particular representation of the data structures in computer memory
Data manipulation model : Accepted axioms and rules for handling the data
SPATIAL DATA MODEL
SPATIAL DATA MODEL
Objects on the earth surface are shown as continuous and discrete objects in spatial data models
Types of data models
Raster data model
vector data models
RASTER DATA MODEL
Basic Elements :
Extent
Rows
Columns
Origin
Orientation
Resolution: pixel = grain = grid cell
Ex: Bit Map Image (BMP),Joint Photographic Expert Group (JPEG), Portable Network Graphics(PNG) etc
RASTER DATA MODEL
VECTOR DATA MODEL
Basic Elements:
Location (x,y) or (x,y,z)
Explicit, i.e. pegged to a coordinate system
Different coordinate system (and precision) require different values
o e.g. UTM as integer (but large)
o Lat, long as two floating point numbers +/-
Points are used to build more complex features
Ex: Auto CAD Drawing File(DWG), Data Interchange(exchange) File(DXF), Vector Product Format (VPF) etc
VECTOR DATA MODEL
RASTER vs VECTORRaster is faster but Vector is corrector
TESSELLATIONS OF CONTINUOUS FIELDS
Triangular Irregular Network: (TIN)
TIN is a vector data structure for representing geographical information that is continuous
Digital elevation model
TIN is generally used to create Digital Elevation Model (DEM)
DIGITAL ELEVATION MODEL
DATA STRUCTURES
Data structure tells about how the data is stored
Data organization in raster data structures
Each cell is referenced directly
Each overlay Is referenced directly
Each mapping unit is referenced directly
Each overlay is separate file with general header
This presentation is about the raster and vector data in GIS which is important and costly as well, through the presentation we will learn about both type of data.
This is most benificial for the First year Engineering students.This presentation consists of videos and many applications of GIS. The processes and the other parts of GIS is also nicely explained.
A geographic information system (GIS) is a system designed to capture, store, manipulate, analyze, manage, and present all types of geographical data. The acronym GIS is sometimes used for geographical information science or geospatial information studies to refer to the academic discipline or career of working with geographic information systems and is a large domain within the broader academic discipline of Geoinformatics. In the simplest terms, GIS is the merging of cartography, statistical analysis, and computer science technology.
This is most benificial for the First year Engineering students.This presentation consists of videos and many applications of GIS. The processes and the other parts of GIS is also nicely explained.
A geographic information system (GIS) is a system designed to capture, store, manipulate, analyze, manage, and present all types of geographical data. The acronym GIS is sometimes used for geographical information science or geospatial information studies to refer to the academic discipline or career of working with geographic information systems and is a large domain within the broader academic discipline of Geoinformatics. In the simplest terms, GIS is the merging of cartography, statistical analysis, and computer science technology.
This is presentation is intended for middle school students. It provides a short introduction to GIS and how to use GIS in the real-world.
ArcGIS Explorer is the software used to demonstrate concepts.
45 minutes + 15 minutes demo
Download ArcGIS Explorer here...
http://www.esri.com/software/arcgis/explorer/
TYBSC IT PGIS Unit I Chapter I- Introduction to Geographic Information SystemsArti Parab Academics
A Gentle Introduction to GIS The nature of GIS: Some fundamental observations, Defining GIS, GISystems, GIScience and GIApplications, Spatial data and Geoinformation. The real world and representations of it: Models and modelling, Maps, Databases, Spatial databases and spatial analysis
GIS (Geographic Information System): is computer assisted system used for collecting, storing, retrieving at will, transforming and displaying spatial data from the real world for a particular set of purpose.
Welcome to our ultimate guide to Geographical Information System (GIS). Discover how GIS revolutionizes data analysis, mapping.
Explore the comprehensive guide to Geographical Information System (GIS). Learn about GIS benefits, applications, and implementation. Click here to uncover the potential.
A Geographical Information System (GIS) is a computer-based tool used to capture, store, manipulate, analyse, and present spatial or geographic data. It combines various types of data such as maps, satellite imagery, aerial photographs, and tabular data to create layers of information that can be visualized and analysed in relation to their geographic location.
GIS technology allows users to explore, interpret, and understand patterns and relationships within geographic data. It provides a framework for organizing and managing data, enabling users to query and retrieve specific information based on spatial and non-spatial attributes. GIS can be used in various fields, including urban planning, natural resource management, environmental assessment, transportation, agriculture, and emergency management
Welcome to TechSoup New Member Orientation and Q&A (May 2024).pdfTechSoup
In this webinar you will learn how your organization can access TechSoup's wide variety of product discount and donation programs. From hardware to software, we'll give you a tour of the tools available to help your nonprofit with productivity, collaboration, financial management, donor tracking, security, and more.
This is a presentation by Dada Robert in a Your Skill Boost masterclass organised by the Excellence Foundation for South Sudan (EFSS) on Saturday, the 25th and Sunday, the 26th of May 2024.
He discussed the concept of quality improvement, emphasizing its applicability to various aspects of life, including personal, project, and program improvements. He defined quality as doing the right thing at the right time in the right way to achieve the best possible results and discussed the concept of the "gap" between what we know and what we do, and how this gap represents the areas we need to improve. He explained the scientific approach to quality improvement, which involves systematic performance analysis, testing and learning, and implementing change ideas. He also highlighted the importance of client focus and a team approach to quality improvement.
Palestine last event orientationfvgnh .pptxRaedMohamed3
An EFL lesson about the current events in Palestine. It is intended to be for intermediate students who wish to increase their listening skills through a short lesson in power point.
Students, digital devices and success - Andreas Schleicher - 27 May 2024..pptxEduSkills OECD
Andreas Schleicher presents at the OECD webinar ‘Digital devices in schools: detrimental distraction or secret to success?’ on 27 May 2024. The presentation was based on findings from PISA 2022 results and the webinar helped launch the PISA in Focus ‘Managing screen time: How to protect and equip students against distraction’ https://www.oecd-ilibrary.org/education/managing-screen-time_7c225af4-en and the OECD Education Policy Perspective ‘Students, digital devices and success’ can be found here - https://oe.cd/il/5yV
The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
The Roman Empire’s society was hierarchical, with a rigid class system. At the top were the patricians, wealthy elites who held significant political power. Below them were the plebeians, free citizens with limited political influence, and the vast numbers of slaves who formed the backbone of the economy. The family unit was central, governed by the paterfamilias, the male head who held absolute authority.
Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
Model Attribute Check Company Auto PropertyCeline George
In Odoo, the multi-company feature allows you to manage multiple companies within a single Odoo database instance. Each company can have its own configurations while still sharing common resources such as products, customers, and suppliers.
The Art Pastor's Guide to Sabbath | Steve ThomasonSteve Thomason
What is the purpose of the Sabbath Law in the Torah. It is interesting to compare how the context of the law shifts from Exodus to Deuteronomy. Who gets to rest, and why?
2. What is GIS?
a computer-based information system used to:a computer-based information system used to:
What is GISWhat is GIS
capture,capture,
manage,manage,
update,update,
analyze,analyze,
display, anddisplay, and
output spatial data and informationoutput spatial data and information
to be used in a decision making contextto be used in a decision making context
GIS (Geographical Information System is:GIS (Geographical Information System is:
3. What is GIS?
Components of a GISComponents of a GIS
HardwareHardware
SoftwareSoftware DataData
PeoplePeople ApplicationsApplications
GIS
4. What is GIS?
Geography Brings Data TogetherGeography Brings Data Together
Multiple Data Layers
Geographically Referenced
Common Coordinate System
Provides basis for:
• Data Integration
• Systematic Analysis
• Customized Maps
6. What is GIS?
The GIS Data Model:The GIS Data Model:
ImplementationImplementation
Geographic Integration of InformationGeographic Integration of Information
Digital Orthophoto
Streets
Hydrography
Parcels
Buildings
Zoning
Utilities
Administrative Boundaries
• Data is organized by layers, coverages or themes (synonomous concepts), with
each layer representing a common feature.
• Layers are integrated using explicit location on the earth’s surface, thus
geographic location is the organizing principal.
7. What is GIS?
GIS Integrates Data & ApplicationsGIS Integrates Data & Applications
Human
Services
Town
Clerk
Senior
Center
Parks &
Recreation
Town
Manager
Finance
Health
Building Police Engineering
Assessor
Planning
Public
Works
Fire
Department
8. What is GIS?
A GIS Manages Two Types of DataA GIS Manages Two Types of Data
Attribute Data (what)
information that defines and
describes each feature
Spatial Data (where)
cartographic features
points, lines & polygons
9. What is GIS?
Spatial and Attribute DataSpatial and Attribute Data
• Spatial data (where)
– specifies location
– stored in a shape file, geodatabase or similar geographic file
• Attribute (descriptive) data (what, how much, when)
– specifies characteristics at that location, natural or human-created
– stored in a data base table
– It is information that is additional to geographical location.
(Spatial Data) E.g. Names, descriptions, labels, statistics,
measurements, categories, codes, dates, symbology.
GIS systems traditionally maintain spatial and attribute data
separately, then “join” them for display or analysis for
example, in ArcView, the Attributes of … table is used to link
a shapefile (spatial structure) with a data base table
containing attribute information in order to display the attribute
data spatially on a map
10. What is GIS?
The GIS Model: LayeringThe GIS Model: Layering
roads
hydrology
topography
Here we have three layers or themes:
--roads,
--hydrology (water),
--topography (land elevation)
They can be related because precise
geographic coordinates are recorded for
each theme.
longitude
latitude
longitude
longitude
latitude
latitude
Layers are comprised of two data types
•Spatial data which describes location
(where)
•Attribute data specifing what, how
much,when
Layers may be represented in two ways:
•in vector format as points and lines
•in raster(or image) format as pixels
All geographic data has 4 properties:
projection, scale, accuracy and resolution
11. What is GIS?
Layers are represented inLayers are represented in RasterRaster or Vectoror Vector formatformat
Raster Model
• area is covered by grid with (usually) equal-sized, square cells
• attributes are recorded by assigning each cell a single value
based on the majority feature (attribute) in the cell, such as land
use type.
• Image data is a special case of raster data in which the
“attribute” is a reflectance value from the geomagnetic
spectrum
– cells in image data often called pixels (picture elements)
• Vector Model
The fundamental concept of vector GIS is that all geographic
features in the real work can be represented either as:
• points or dots (nodes): trees, poles, fire plugs, airports, cities
• lines (arcs): streams, streets, sewers,
• areas (polygons): land parcels, cities, counties, forest, rock
type
Because representation depends on shape, ArcView refers to files
containing vector data as shapefiles
12. What is GIS?
0 1 2 3 4 5 6 7 8 9
0 R T
1 R T
2 H R
3 R
4 R R
5 R
6 R T T H
7 R T T
8 R
9 R
Real World
Vector Representation
Raster Representation
Concept of
Vector and Raster
line
polygon
point
13. What is GIS?
Street Network layer: lines Land Parcels layer: polygons
Raster (image) Layer
Digital Ortho Photograph Layer:
Digital Ortho photo: combines the visual
properties of a photograph with the positional
accuracy of a map, in computer readable
form.
Vector
Layers
Layers
Projection: State Plane, North Central Texas
Zone, NAD 83
Resolution: 0.5 meters
Accuracy: 1.0 meters
0 1500 3000 Feet
16. What is GIS?
GIS Applications – What GIS is used forGIS Applications – What GIS is used for
• Property assessment
• Wetlands regulation
• Emergency response
• Infrastructure management
• School redistricting
• Law enforcement
• Open space planning
• Greenway planning
• Access to health services
• Forest management
• Homeland security
• Transportation planning
• Site suitability / selection
• Build-out analysis
• Search and rescue
• Plans of C & D
• Map design & production
• Watershed protection
• Permit review
• E-911
• Farmland protection
• Aquifer protection
• Archaeological research
• Economic development
17. What is GIS?
Examples of Applied GISExamples of Applied GIS
• Urban Planning, Management &
Policy
– Zoning, subdivision planning
– Land acquisition
– Economic development
– Code enforcement
– Housing renovation programs
– Emergency response
– Crime analysis
– Tax assessment
• Environmental Sciences
– Monitoring environmental risk
– Modeling stormwater runoff
– Management of watersheds,
floodplains, wetlands, forests,
aquifers
– Environmental Impact Analysis
– Hazardous or toxic facility siting
– Groundwater modeling and
contamination tracking
• Political Science
– Redistricting
– Analysis of election results
– Predictive modeling
• Civil Engineering/Utility
– Locating underground facilities
– Designing alignment for freeways, transit
– Coordination of infrastructure
maintenance
• Business
– Demographic Analysis
– Market Penetration/ Share Analysis
– Site Selection
• Education Administration
– Attendance Area Maintenance
– Enrollment Projections
– School Bus Routing
• Real Estate
– Neighborhood land prices
– Traffic Impact Analysis
– Determination of Highest and Best Use
• Health Care
– Epidemiology
– Needs Analysis
– Service Inventory
18. What is GIS?
Provide examples of data pre-processing.
(1) Georeferencing– The process of giving images in your
GIS real-world coordinates.
(2) Digitising— features on paper-based maps are traced
using a mouse type device called a cursor (it is stored
in vector format)
(3) Scanning— a scanner converts hardcopy maps and
documents into digital images.
(4) Features and Attribute tables— Attributes are attached
to the vector feature in the GIS by using a data table.
The columns are the different kinds of attributes, the
rows are the individual vector features that have been
digitized.
19. What is GIS?
Name and explain 4 steps to follow when creating a GIS
project.
1)Data collection. The process of finding data.
2) Data pre-processing. Data is made user-friendly by undergoing distortion
adjustments and geometric registration. (See slide on data pre-processing).
3) Data Management. Storing and updating large amounts of data and making it
easier for users to find the data.
4) Data Analysis and Manipulation. Data can be analyzed and change into
information.
ApplicationsApplications
20. What is GIS?
What is a GIS project? (Provide some
examples of GIS projects).
A Gis project is one that uses spatial / geographical data to answer
a particular question:
1) Agriculture: How can food production be improved?
2) Emergency: What is the fastest route to the hospital?
3) Retail: Where is the best to build a new shopping centre?
4) Marketing: Where do the people live that I want to sell to?
21. What is GIS?
GIS ProjectsGIS Projects
• Locating a Day-care
– intro to GIS capabilities
– illustration of a major application: site selection
• Texas Demographic growth
– manipulation of data and mapping principles
– another major application: analysis of spatial patterns with polygon
data
• Geocoding Housing Sales, or Analyzing Earthquake
Locations
– techniques and data requirements for geocoding and point
patterns
– another application: geocoding/address matching
• Creating a Census Tract layer, or a Geological Map
– editing and creating topologically consistent data
– how new data layers can be created
• Pipeline Routing
– data selection, buffering and spatial analysis
– another major application: corridor studies
22. What is GIS?
Perform Spatial AnalysesPerform Spatial Analyses
Find
Buildings
Within 250m of streams
23. What is GIS?
Public Utility ApplicationsPublic Utility Applications
Select Suitable Site for Water
Company Well
.
Water Company
Service Area
Only within undeveloped land
areas
Within undeveloped land area, only
outside buffer of polluted streams
and known point sources of pollution.
Only surface geology that shows greatest
potential for water production
24. What is GIS?
How does GISHow does GIS
data get stored?data get stored?Data
Decisions
Science
M
anagem
ent
Many GIS applications store digital data in a database.
GIS data is stored in a number of file formats, but the
shape file is the most common. It consists of at least
three different files that work together to store digital
vector data as shown in the table below.
A database is a storage system linked to tables.
25. What is GIS?
Sources of data used in a GIS
1)Primary data: Data collected in the field by physically measuring, observing and
interpreting objects e.g. GPS measurements, scanned in maps.
2) Secondary data: Data that already exists in one format or another. It is data that can
be reused e.g. maps, databases, images and aerial photographs.
Name two ways in which primary data is collected.
1) Ground-based surveys. E.g tachymetry
2) GPS
26. What is GIS?
What is metadata?
Metadata is data about data.
Provide some examples of metadata.
Names of people responsible for creating the data.
A textual description of the content of the data.
Dates and times of when the data was produced.
Map projection / spatial resolution used.
27. What is GIS?
GIS aspects that need agreement on global
standardisation include:
•The global map projections used.
•Methods of Georeferencing.
•Geographical names.
•Units of measurement used.
•Methods of processing digital data.
Data Standardisation
Growing of GIS has resulted in intense efforts at data
standardisation to establish structures and methods for
the interchange of spatial data.
28. What is GIS?
Data sharing offers several advantages:
•It avoids expensive repetition of data
acquisition (e.g. sensors in orbit).
•It makes a wide range of data available to
people all over the world.
•It reduces workload and cost
Data Sharing
Data sharing between organisations with different GIS
could only be achieved by data converters, transfer
standards and open file formats.
29. What is GIS?
Data is protected in several ways:
•Data must be secure from loss or computer failure.
•Data must be secure from fraud.
•Some files (databases) of municipalities and the
government must be kept secret.
•The police, fire brigade and ambulance have data
files that would be of interest to criminals / terrorists
and have to be protected.
Data Security
Data and information can sometimes be highly sensitive,
either for commercial or personal confidentiality or
national security. To ensure data security the data can
only be accessed with authorisation codes.
30. What is GIS?
Data Manipulation
Data needed for GIS comes from
many different sources. They will
need to be transformed or
manipulated in some way to
make them compatible with the
GIS system
Examples of Data Manipulation:Examples of Data Manipulation:
Creation of buffers, creation of models, integration of data layers,
conversion of data from raster and vector formats, interpolation
between points .
31. What is GIS?
To correct distortionsTo correct distortions
Why is it necessary to manipulateWhy is it necessary to manipulate
data in a database?data in a database?
To sharpen definitionsTo sharpen definitions
To ensure colour consistencyTo ensure colour consistency
To ensure correct latitude andTo ensure correct latitude and
longitudelongitude
Linked database tableLinked database table
Spatial dataSpatial data
32. What is GIS?
Data Integration
What are the problems of integrating data?
Maps have different scales
Maps have different projections
Maps have different georeferences
What is the importance of integrating
data?
A summary of integrated data is
produced and is easier to
understand
Data integration involves the combination of two or more
layers in order to create a new one.
33. What is GIS?
Data Querying
You can begin to ask questions:
GIS allows querying in order to answer Geographical questions
and help solve complex problems. It’s displayed graphically!
The vegetation layer is compared with the soil data layer. The shrubs
and sand areas are overlaid and only the areas adhering to the query
are shown.
34. What is GIS?
Answers to Simple QuestionsAnswers to Simple Questions
?
Visualize spatial
relationships
Answer questions
about what “it” is
Answer questions
about where things
are
Ad hoc queries are one of the
most important and basic of all
GIS functions
Ad hoc queries are one of the
most important and basic of all
GIS functions
35. What is GIS?
• That were sold in
the past 3 years
• For more than
$200,000
Queries - Class of FeaturesQueries - Class of Features
• Select all parcels
in a subdivision
36. What is GIS?
A buffer refers to an area around a point, line or polygon.
You can demarcate a buffer area of for example 3 km around a place on
the map.
EXAMPLES OF BUFFERING: What is the total number of customers
within 10 km of this shopping mall? Which areas will be affected by a 1m
rise in sea level? Which residential areas will be affected by a nuclear
fallout affecting a radius of 60 km from the nuclear power station?
MapInfoMapInfo
Buffering
37. What is GIS?
Statistical Analysis
Information such as:
Statistical Analysis is used to investigate GIS
data and assist in the identification of
additional information.
Spatial patterns
Spatial trends
Climatic averages e.g. temperature and
rainfall
Which layers would GIS researches use to
determine the risk of a landslide:
Altitude Slope angle
Rock type Land cover
Slope exposure Distance from rivers
Profile curvature Surface curvature
Distance from the road Drainage Basin
38. What is GIS?
What remote sensing is used for:
Remote sensing is obtaining data from a distance without touching the object.
Instruments used to collect the information are the camera, radar, sonar, thermal
and electro-optical sensors.
Remote sensing is used to study weather patterns, climate change, urban change,
the atmosphere, landscapes, ecosystems, human impact on the environment, the
oceans and hydrology.
39. What is GIS?
Spatial ResolutionSpatial Resolution
• Satellite images are captured in digital format.
• They consist of a very fine grid of squares called
‘picture cells’ or ‘pixels’. (Raster data)
• Coarse (low) resolution if the pixel covers a
large area on the ground
• Fine (high) resolution covers a smaller area
on the ground.
Spatial Resolution refers to the size of an object that can
be recorded; the most usual method is the pixel size.
40. What is GIS?
Spectral ResolutionSpectral Resolution
Spectral resolution refers to the width of the wavelength intervals that are being
measured in the electromagnetic spectrum.
Remote sensors can collect data in the visible part of the spectrum (to provide
images such as aerial photographs).
Other sensors may collect data in the invisible sectors like infrared (seen below)
and ultraviolet.
41. What is GIS?
Vertical Aerial Photograph – Taken from
above, camera is pointing vertically
downwards.
High Oblique Aerial Photograph – Horizon
is visible. Camera is tilted at 68 degrees.
Low Oblique Aerial Photograph – Horizon is not
visible. Camera is tilted at 30 degrees.
Editor's Notes
A GIS is not just hardware and specialized software; it also includes data, applications, people and procedures for its use and maintenance.
Applications are perhaps the most important yet overlooked component of a GIS. Applications are what a GIS will be used for. They determine many of the other elements of a system; for example, what data will be necessary, how it will be processed, who will access the data and what products or information the system will produce. Having a clear understanding of applications and system use is a critical first step to system design and implementation.
The purpose of this slide is allow the presenter to list the major components of a GIS and to discuss how they are integrated into a SYSTEM.
Hardware and software range from stand-alone desktop systems to complex enterprise-wide networks.
Data include existing public domain data sets, an organization’s own data that may be created in-house or through arrangements with another organization or vendor. Note that data are expensive, both to create and to maintain. Higher accuracy data cost orders of magnitude more than less accurate data. Accuracy and cost should match the requirements of the applications.
Applications and procedures define the uses of the GIS and the standardized methods, if appropriate, that will insure consistent high quality output and analyses. The applications determine data needs.
Trained and knowledgeable people to operate and maintain a system are essential. They can be expensive and they need continued training.
Note that GIS data consist of cartographic features:
Pointswells, utility poles, manholes
Linesroad centerlines, small streams, trails
Polygonsparcels, wetlands, building footprints, watersheds
AND
Attribute data that describe each feature
AND that features and attributes are linked
This permits accessing and analyzing GIS data either based on where it is or what it is; on in some cases based on a combination of where and what.
This example retrieves data for a single feature. Simply click on the polygon and its database record will be displayed.
Ad hoc queries such as this are a prime use of GIS.