basic concept of geographic data,GIS and its component,data acquisition ,raster, vector formats,spatial data,topology and data model data output ,GIS applications
Topics:
1. Introduction to GIS
2. Components of GIS
3. Types of Data
4. Spatial Data
5. Non-Spatial Data
6. GIS Operations
7. Coordinate Systems
8. Datum
9. Map Projections
10. Raster Data Compression Techniques
11. GIS Software
12. Free GIS Data Resources
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.
Topics:
1. Introduction to GIS
2. Components of GIS
3. Types of Data
4. Spatial Data
5. Non-Spatial Data
6. GIS Operations
7. Coordinate Systems
8. Datum
9. Map Projections
10. Raster Data Compression Techniques
11. GIS Software
12. Free GIS Data Resources
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 document help you to prepare Triangulation Network (TIN), Hillshade Map, Slope map, interpolation and Digital Elevation Model (DEM) in a area and how to interpret them.
Digital Elevation Model (DEM) is the digital representation of the land surface elevation with respect to any reference datum. DEM is frequently used to refer to any digital representation of a topographic surface. DEM is the simplest form of digital representation of topography. GIS applications depend mainly on DEMs, today.
Gis Geographical Information System FundamentalsUroosa Samman
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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.
One of most important topics in ArcGIS and GIS, is coordinate system, the slides will cover this topic in order to understand the difference between various coordinate systems.
An introduction to GIS Data Types. Strengths and weaknesses of raster and vector data are discussed. Also covered is the importance of topology. Concludes with a discussion of the vector-based format of OpenStreetMap data.
Mumbai University, T.Y.B.Sc.(I.T.), Semester VI, Principles of Geographic Information System, USIT604, Discipline Specific Elective Unit 1: Introduction to GIS
Introduction -Remote means – far away ; Sensing means – believing or observing or acquiring some information.
Remote sensing means acquiring information of things from a distance with sensors. (without touching the things)
Sensors are like simple cameras except that they not only use visible light but also other bands of the electromagnetic spectrum such as infrared, microwaves and ultraviolet regions.
Distance of Remote Sensing, Definition of remote sensing - Remote Sensing is:
“The art and science of obtaining information about an object without being in direct contact with the object” (Jensen 2000).
India’s National Remote Sensing Agency (NRSA) defined as : “Remote sensing is the technique of deriving information about objects on the surface of the earth without physically coming into contact with them.”
Remote Sensing Process, - (A) Energy Source or Illumination.
(B) Radiation and the Atmosphere.
(C) Interaction with the Target.
(D) Recording of Energy by the Sensor.
(E) Transmission, Reception, & Processing.
(F) Interpretation and Analysis.
(G) Application.
Remote sensing platforms , History of Remote Sensing, Applications of remote sensing - In Agriculture, In Geology, Applications of National Priority.
This document help you to prepare Triangulation Network (TIN), Hillshade Map, Slope map, interpolation and Digital Elevation Model (DEM) in a area and how to interpret them.
Digital Elevation Model (DEM) is the digital representation of the land surface elevation with respect to any reference datum. DEM is frequently used to refer to any digital representation of a topographic surface. DEM is the simplest form of digital representation of topography. GIS applications depend mainly on DEMs, today.
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.
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.
One of most important topics in ArcGIS and GIS, is coordinate system, the slides will cover this topic in order to understand the difference between various coordinate systems.
An introduction to GIS Data Types. Strengths and weaknesses of raster and vector data are discussed. Also covered is the importance of topology. Concludes with a discussion of the vector-based format of OpenStreetMap data.
Mumbai University, T.Y.B.Sc.(I.T.), Semester VI, Principles of Geographic Information System, USIT604, Discipline Specific Elective Unit 1: Introduction to GIS
Introduction -Remote means – far away ; Sensing means – believing or observing or acquiring some information.
Remote sensing means acquiring information of things from a distance with sensors. (without touching the things)
Sensors are like simple cameras except that they not only use visible light but also other bands of the electromagnetic spectrum such as infrared, microwaves and ultraviolet regions.
Distance of Remote Sensing, Definition of remote sensing - Remote Sensing is:
“The art and science of obtaining information about an object without being in direct contact with the object” (Jensen 2000).
India’s National Remote Sensing Agency (NRSA) defined as : “Remote sensing is the technique of deriving information about objects on the surface of the earth without physically coming into contact with them.”
Remote Sensing Process, - (A) Energy Source or Illumination.
(B) Radiation and the Atmosphere.
(C) Interaction with the Target.
(D) Recording of Energy by the Sensor.
(E) Transmission, Reception, & Processing.
(F) Interpretation and Analysis.
(G) Application.
Remote sensing platforms , History of Remote Sensing, Applications of remote sensing - In Agriculture, In Geology, Applications of National Priority.
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/
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.
the title of this course is Entitles as GIS and Remote sensingmulugeta48
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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.
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Geographic information system (gis)
1.
2. UNIT IV
GEOGRAPHIC INFORMATION SYSTEM (GIS)
Geographic Information System is a System containing
Information which is geographic in nature.
GIS can be defined as - A System which involves collecting/capturing, storing, processing and
manipulating, analyzing, managing, retrieving and displaying data (information) which is,
essentially, referenced to the real-world or the earth (i.e. geographically referenced).
Explanation of the Definition
1. Collection/Capturing
The dataset collected for GIS may be in the form of hard copy maps, satellite images,
survey data or other data obtained from other primary and secondary sources.
Collection of data depends on the objective of the assignment. Data capturing involves
digitization of hard copy maps and satellite images.
2. Storage
In GIS Storage means not merely storing whatever data we have collected. The
collected data is converted in usable GIS format and then finally stored for further use
either on computer hard disk or in other storage devices (CD, DVD, magnetic tapes etc.)
3. …….Cont.
3. Processing and Manipulation
The collected and stored dataset is imported and converted into layers. Then required
attributes are attached. Then data is processed for refinement, removing errors and
preparing it for further GIS-based analysis. Data manipulation is essential so that it can
be represented in proper understandable form.
4. Analysis
Analysis of GIS data is required to convert it into desired outputs. There are many type of
analysis in GIS which is (or are) to be done is objective dependant. The analysis may be
statistical, spatial or specialized (like network analysis, utility analysis etc. Need not to say
GIS analysis requires skilled professionals.
5. Management
Data management is essential and very important part of GIS for storing, managing and
properly maintaining GIS database.
6. Retrieval
In GIS, data can be retrieved through SQL or spatial queries. Some software provide tools to
retrieve data by simply selecting the features. Retrieval is used for getting information about the
features of our interest.
7. Display
Displaying of final output may in many forms. These may be hard copy printouts, on-screen
display of maps, internet-based map display (through Internet Map Servers) or in the form of
presentation (like power point).
9. GIS Components
Following five essential components make a complete Geographic Information
System. Even imagine about GIS is not possible if we remove one of these
components. All components are important (however some may be more some
may be less).
1. Hardware
2. Software
3. Data
4. Method
5. People
10. Types of GIS Data
GIS data can be broadly described as
1. Spatial data and
2. Non-spatial data.
Spatial data
Spatial data is geographical representation of features. In other words, spatial
data is what we actually see in the form of maps (containing real-world features)
on a computer screen. Spatial data can further be divided into following two
types;
a). Vector data
b) Raster data.
12. What makes data spatial?
OR
Features /Characteristic of Spatial Data
Grid co-ordinate
Place Name
Latitude / Longitude
Post Code
Description
Distance & bearing
12
13. Vector Data:
It represent any geographical feature through point, line or polygon or
combination of these.
Point: A point in GIS is represented by one pair of coordinates (x & y). It is
considered as dimension-less object. Most of the times a point represent location
of a feature (like cities, wells, villages etc.).
Line: A line or arc contains at least two pairs of coordinates (say- x1, y1 & x2, y2).
In other words a line should connect minimum two points. Start and end points of a
line are referred as nodes while points on curves are referred as vertices. Points at
intersections are also called as nodes. Roads, railway tracks, streams etc. are
generally represented by line.
Polygon (or Area) : It is a closed line with area. It takes minimum three pairs of
coordinates to represent an area or polygon. Extent of cities, forests, land use etc.
is represented by polygon.
14.
15.
16.
17. Raster Data
Raster data is made up of pixels. It is an array of grid cells with columns and rows.
Each and every geographical feature is represented only through pixels in raster
data. There is nothing like point, line or polygon. If it is a point, in raster data it will
be a single pixel, a line will be represented as linear arrangement of pixels and an
area or polygon will be represented by contiguous neighboring pixels with similar
values.
In raster data one pixel contain only one value (unlike vector data where a point, a
line or a polygon may have number of values or attributes) that’s why only one
geographical feature can be represented by a single set of pixels or grid cells.
Hence a number of raster layers are required if multiple features are to be
considered (For example- land use, soil type, forest density, topography etc.).
As discussed earlier digital satellite images are also in raster format.
18.
19.
20. NON-SPATIAL DATA
Attributes attached to spatial data are referred to as non-spatial data. Whatever
spatial data we see in the form of a colourful map on a computer screen is a
presentation of information which remains stored in the form attribute tables.
Attributes of spatial data must contain unique identifier for each object. There
may be other field also containing properties/information related a spatial
feature. Attribute table of spatial data also contains ‘x’ and ‘y’ location (i.e.
latitude/longitude or easting/northing) of features; however in some GIS
software these columns may remain ‘invisible’.
For example- if we are doing demographic analysis of villages then attributes of
each point (representing a village) must have a unique village ID and other
demographic information like total population, number of males & females,
number of children etc.
In another example- if we are doing some GIS analysis related to road then
each road must have its unique Road ID. Other attributes may include like road
length, road width, current traffic volume, number of stations etc.
22. Input data for GIS (or Data sources/Data acquisition)
Input data for GIS cover all aspects of capturing spatial data and attribute data. The
sources of spatial data are existing maps, aerial photographs, satellite imageries, field
observations, and other sources as shown in figure. The spatial data not in digital form
are converted into standard digital form using digitizer or scanner for use in GIS. The
entire process is reffered as data aquisition
Maps
Aerial
Photo
Satellite Imageries
Field Observations
Other
Sources
Digital Input
Data
Terrain
data
GIS
Database
23. Working with GIS Database
Data storage sub
system
GIS
Database
Data and analysis
subsystem
Modelling and
analysis
Reporting and output
subsystem
GIS
Output
as per User
24. Spatial Data Modelling
To make geographic data useful, it should be encoded in digital form, and
organized as a digital geographical database that creats a perception of
the real world similar to the perception created by the paper maps.
Type of spatial data modelling :
1. object based model. The geographic space is treated to be filled by
discrete and identifiable objects. A object which is a spatial
feature, has identifiable boundaries ,relevance to some intended
application, and can be described by one or moor more
characteristics known as attributes.
spatial object such as
• Exact objects (building ,roads etc)
• Inexact objects(landform fearture , and wildlife habitat)
1. Field based model. The field based model treats geographic space
as populated by one or more spatial phenomena of real world
feartures varing continuously over space with no obvious or specific
extend
25. Database Models
Model is a set of plans for a building, therefore, modelling of database means a methodologies
to be followed for some specified purpose. It specify the structure of database. Common
approach for this purpose include;
1. Digital Elevation Model (DEM)
2. Triangulated Irregular Network (TIN)
Digital Elevation Model (DEM)
It is a sampled array of elevations (z) that are at regularly spaced intervals in the x and y
directions. Two approaches for determining the surface z value of a location between sample
points are followed.
a). Lattice: each mesh point represents a value on the surface only at the center of the
grid cell. The z-value is approximated by interpolation between adjacent sample
points; it does not imply an area of constant value.
b). Surface grid: considers each sample as a square cell with a constant surface value.
Advantages
• Simple conceptual model
• Data cheap to obtain
• Easy to relate to other raster data
• Irregularly spaced set of points can be
converted to regular spacing by
interpolation
• Linear features not well represented
Disadvantages
Does not conform to variability of
the terrain
26. Representation of DEM
After a satellite image has been combined with a DEM, one gets a representation like
that shown here and known as Digital Terrain Model (DTM).
27. Triangulated Irregular Network (TIN)
It is a set of adjacent, nonoverlapping triangles
computed from irregularly
spaced points, with x, y
horizontal coordinates and z
vertical elevations.
• Advantages
– Can capture significant
slope features (ridges,
etc)
– Efficient since require
few triangles in flat areas
– Easy for certain
analyses: slope, aspect,
volume
• Disadvantages
– Analysis involving
comparison with other
layers difficult
28. GIS Data Models
The real world can only be depicted in a GIS through the use of models that define
phenomena in a manner that computer systems can interpret and perform meaningful
analysis. There are two types of GIS Data Models
1. Vector Model
2. Raster Model
Raster data model
– location is referenced by a grid
cell in a rectangular array (matrix)
– attribute is represented as a single
value for that cell
– much data comes in this form
• images from remote sensing
(LANDSAT, SPOT)
• scanned maps
• elevation data from USGS
– best for continuous features:
•
•
•
•
elevation
temperature
soil type
land use
Vector data model
– location referenced by x,y
coordinates, which can be linked
to form lines and polygons
– attributes referenced through
unique ID number to tables
– much data comes in this form
• DIME and TIGER files from US
Census
• DLG from USGS for streams,
roads, etc
• census data (tabular)
– best for features with discrete
boundaries
• property lines
• political boundaries
• transportation
29. GIS Applications
The application of geospatial sciences has spread very fast and wide over the past few
decades. User's of GIS's range from indigenous people, communities, research
institutions, environmental scientists, health organizations, land use
planners, businesses, and government agencies at all levels.
Environment
1. Conservation & Monitoring
2. Planning & Policy
3. Wetland Management
4. Wildlife Management
5. Forest Management
6. Water Pollution
7. Air Pollution
8. Climate Change
Geology
1. Mineral & Mining
2. Geomorphology
3. Products
Agriculture
1. Overview
2. Crop Production
3. Crop Pattern
4. Crop Yield
5. Irrigation
6. Soil Management
Urban Planning
1. Urban Sprawl
2. Fringe Area Development
3. Urban Agglomeration
4. Emerging Technologies
30. GIS Applications
Natural Resource Management
1. Mountain
2. Water Resources
3. Ocean
4. Coastal Zone Management
Land Information System
1. Policy
2. Rural & Cadastral
3. Urban
5. Corporate Case Studies
Natural Hazard Management
1. Earthquake
2. Drought
3. Fire
4. Flood & Cyclones
5. Landslide & Soil Erosion
6. Volcano
…..cont.
Utility
1. Power
2. Telecom
3. Transport