intorduction_day1

Fundamental of GIS

GIS: Evolution of Mapping Technology

•A map is a picture of a place and gives you better understanding ofthat place I.e. map contains information.

•Map is a two-dimensional representation of a particular place.

•Maps are made for many reasons and therefore they vary incontent and context. Different maps show different information.

•Different symbols are used to represent the features on earth ontoa map, which are explained in the legend. The legend in a map tellswhat each map shows.

You and Maps Understanding the world better

Some examples: A picture of the place

Aerial

photograph


Topographic map

Shaded relief map


GIS Day 2000 NEPAL: Promoting Geographic Literacy Through GIS

Road/ Tourist map

3D map

Map Scale� Map scale describes the relationship between mapped size and actual size.

It is expressed as a relationship between linear distances on the map and

corresponding ground distances.

� Inch-Foot Equivalent

The scale relationship is expressed as "1 inch = x feet" where the map

distance of 1 inch is compared to its corresponding ground distance.

� Representative Fraction (RF)

This is a pure fraction that represents the ratio of map distance to ground

distance without specifying any measurement unit. The inch-foot

equivalent of 1" = 100' is represented in RF form as 1:1,200 or 1/1,200

Map scale

• Large-scale maps cover small areas, but can include a higher level of detail than small-scale maps which depict larger areas at lower detail.

• There are no precise definitions of large- or small-scale, but for most map users, the following scale, but for most map users, the following general scale categories apply:

Large-scale: 1:2500 or larger

Medium-scale: 1: 2500 to 1: 10000

Small-scale: 1:10000 to 1:50,000

Very Small-scale: smaller than 1: 50000

Map ProjectionThe globe is the best way to show the relative positions of places, but they are not portable and practical for large scales.

Due to the three-dimensional shape of the earth, it is not possible to depict locations and features in the two-dimensional map space directly and without some distortions.

Map projection is a procedure to transform locations and features from Map projection is a procedure to transform locations and features from the three-dimensional surface of the earth onto the two-dimensional paper in a defined and consistent way.

Plate Carree Projection and Albers Equal Area Projection with Tissot Incatrix

Maps: Analogue and digitalMaps are rigid in analogue format though they convey message by

virtue of symbology.

Maps in hardcopy are impossible to be integrated with other data.

They are measurable but not interactive.

They are always projected.

All these negations are overcome

by GIS

Evolution of GIS……..Roger Tomlin, the father of Canada GIS, is credited for visualizing the

need of computers to perform certain simple but labor-intensive task

associated with Canada Land Inventory.

David Bickmore (1934), the primary GIS innovator discovered GIS

stems from the benefits of automating the map production process.

Ray Boyle invented the free-pencil digitizer and by 1964 Bickmore

and Byole set up the Oxford System for high quality digital

cartography.cartography.

Thereafter major mapping agencies from US and other military bodies

began rocky and lengthy process of automation.

During mid 1970s, widespread availability of high capacity hardware

and innovative software mechanism helped to convert analogue map

to digital.

Use of the McHarg proposed representation (on 1969) of geo-spatial

entities in layered form (1989) And use of topology in data US Census Bureau 1990

Chronology and evolution….

ROOTS OF GIS• GIS deeply rooted by virtue of its capacity of

integrating data from other sources and RS

imagery based on some common criterion and …..

GIS

Data storage Large scale data integration

around common data model

Landscape architect

and environmental planningSpatio-temporal Modelling

GIS: A subset of information System

• To improve ones ability to make decisions.

• Starts from the user feeling of need

• Chain of operations

• Ends at the fulfill of user need.

Demand/ Satisfaction

User needDemand/ Satisfaction

User Action

Planning Data collection Data Storage

Output Products

Manipulation

and AnalysisGIS

GI for 4Ms

MeasurementMonitoring

Suitability model

DEMLand use/ Land cover

MappingModeling

GISDEM

Utility network

Ground water

Land use/ Land cover

Agriculture

Hydrology

Contributing Disciplines

Geography

Photogrammetry

Remote Sensing

Statistics

Cartography

Software Technology Surveying

Remote Sensing

WWW

Mathematics

GIS

Where is my Land parcel in this vast terrain?

GIS• G Geographic Related to entities on

the ground

• I Information Data Interpreted as an

something that gives you insight on the issue

• S System Integration of different

well working parts which themselves may be a

system but are the subsystem of the universal

system in consideration

GIS DEFINED

• Architect Geographic

Information System is

defined as a system in

digital environment that

involves on geographic

data input, Spatial data input, Spatial

analysis and output

GIS Architecture

GIS : A main system framework composed

of coordinated multiple subsystem.

GIS

Data Acquisition

Subsystem

Data Storage

Subsystem

Data Analysis /

Manipulation

Subsystem

Data output

Subsystem

Terminologies• Entities: Real Object on the ground

• Fields: Way of the representation of the entities in the digital

system.

• Spatial : Object that has geometry

• Aspatial or attribute : A property of the spatial object that

describes

• Model : Generalized Computer representation of a given

phenomena

• Topologies: Geometrical characteristics of features which do

not changed under transformation and are independent of

coordinated system.

Questions GIS can answer

GIS can be distinguished by listing the types of

questions it can answer.

• Location- What is at...?

The first of these questions seeks to find what exists at a

particular location. A location can be described in many

ways, using, for example, place name, postcode, or

geographic reference such as longitude/ latitude or x and y.

Questions GIS can answer Condition- Where is it...?

The second question is the converse of the first and requires spatial data to answer. Instead of identifying what exists at a given location, one may wish to find locations where certain conditions are satisfied (e.g., a non-forest area of at least 2,000 square metres in size, within 100 metres of a road, and with soils suitable for supporting buildings).

Residential Land Use

4 Bed rooms

Made of local bricks

Assessment < Rs. 500,000

Condition- Where is it...?

Where are houses located that you might consider buying

Questions GIS can answerGeographic Literacy Through GIS

Trends- What has changed since...?

The third question might involve both of the first two and seeks to find the differences within an area over time, for example, changes in forest cover or the extent of urbanization over the last ten years.

Patterns - What data are related...?

Patterns- What spatial pattern exists...?

This question is more sophisticated. One might ask this question to determine whether landslides are mostly occurring near streams, or to find out which


are the traffic points where the accidents occur more frequently. It might be just as important to know how many anomalies there are that do not fit the pattern and where they are located.

What kind of pattern exists for vehicle accidents?


Modeling- What if...?

Through GIS

“What if…” questions are posed to determine what happens, for example, if a new road is added to a network or if a toxic substance seeps into the local groundwater supply. Answering this type of question requires both geographic and other information (as well as specific models).

Health centre?

School?

Hotel?

Post office?

• GIS Components

Software

Peoples

Data

GIS

Software Data

ProceduresHardware

Workflow

Geometric correction/ relief

correction

Image fusion(optional)Updated Database

(MSS/PAN) Digital

Image

Radiometric

correction

Classification

Existing

Vectors

Database

Study of VectorSelected Subset

Overlaying of image data or

fused image and Vectors

Data

Analysis /

Change detection/

Visual Interpretation

Vectorize the changed

(detected) data into

different Layers

Get the detected

data into the

relevant set of data

of Top 25/ 50

vectors after

removing the old

data from the

database.

Satellite Image

Map of concerned

area

Cartographic

Processing

New Updated

Maps

Field

verification

Value added

products

Verified

Note: The final out put is shown in the background-shaded figures.

intorduction_day1

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