I had to give presentation on GIS as a part of my CEC marks so here I have included all the points which are there in my curriculum and its all about Geographical Information System - GIS.

1. Geographical Information System

2. What is GIS?
• Any manual or computer based system design to store, analyze,
manipulate, display spatially referenced data.
• The ultimate purpose of GIS is to answer spatial questions and not
necessarily making pretty MAPS!!!
• GPS and online maps works on GIS.
2

3. Spatial Data
• Information related to “existing space”.
• Since the whole system deals with aspects of our everyday life, it
suppose to be updated regularly to keep it current and reliable.
• It is made of longitude and latitude.
3

4. What makes it GIS? (components)
4

5. Components of GIS
• Hardware & Software
– Hardware is a physical device which can be used by the end users like
a graphic device or a plotter or scanner.
– Software is related to processes to define, store and manipulate the
data like a DBMS.
– GIS follows 3 tier architecture and still different modules are applied to
GIS to provide efficient service.
• Data
– It is divided in 2 categories: Vector and Raster.
5

6. Vector:
Made up of a dot.
Objects are represented by points, lines and polygons.
Raster:
Made up of pixel.
Can be of 2 dimension (pixel of block) or 3 dimension (voxel).
It is made up by adding different layers.
6

7. Raster / Vector maps

8. People
People are involved in each part of GIS.
That includes cartographers and analyst who who creates the maps and
surveys the land.
System users who collects the data, upload data to system, manipulate
the system and analyze the result.

9. Characteristics of data in GIS
• Location
– Location of an object is specified by co ordinates in system
– It is shown by point, line or a polygon.
• Temporality
– A database should record existence and its updated location of an
object both.
– It is crucial when it is require to find a path in a dynamic fashion like
tracking a land parcel.

10. Thematic Value
Different properties and qualities of an object may be represented as
attributes.
Fuzzy Object
Deals with the uncertainty of an object’s location and thematic
classification.
The location of an object is represented by degree of error.
Countries and states are always on a dynamic state of moving
boundaries, roads and buildings cause 100% accuracy may not be kept
while recording it.
Object ID
Object should be uniquely identified in the data model in the data model.
Eg National Highway 8, Western Express Highway.

11. Entity v/s field based data
The world can be represented as a set of discrete entity such as forests,
rivers, roads and buildings which is referred as Entity Based Approach.
Field based approach represents world as natural phenomenon like air
pollution or may be humidity.
Generalization
Objects may be aggregated from larger to lower scale while opposite may
not be possible.
Collection of pixels having 2 Mtr dimensions can be aggregated to
generate a pixel of 10 Mtr but 10 Mtr pixel can’t be aggregated to
generate a pixel of 2 Mtr.
States can be aggregated to generate a country but aggregated countries
can’t be aggregated to generate a state, that doesn’t make sense even!

12. Data Quality
Refers to the credibility and accuracy of the data and more generally how
good data is.
Quantitative quality refers to the measurable components such as spatial
accuracy.
Qualitative quality refers to the non-measurable components and some
specific objects like area of a mountain.

13. Constraints of GIS
• As a part of constraints a GIS database may have primary key, foreign key
etc.
• A state and country is going to have a capital which can be kept as primary
key and one can track the country by selecting a state which can be done
with having a foreign key
• This constraints are classified in 4 categories.
13

14. Topological Integrity Constraint:
Deals with the behavior of features and the spatial relationship between
them.
Used during insert and update processes to help reduce errors and
improve data quality.
Semantic Integrity Constraint:
Defines whether the database state is valid according to semantic rules
that apply to features.
Eg a road declared as ONE WAY or ENTRY RESTRICTED.
User-defined Integrity Constraint:
Refers to the rules made by humans.
Eg. A house should be having a 10 ft distance from a main road.

15. Temporal Constraint:
That are differentiated in punctual and durable temporality.
Punctual temporality refers to event with a specific time such as an
accident, earthquake, party and so on.
Durable temporality refers to the event occur over a period of time like a
bridge built and demolished after some years.
Generalization is also considered as a constraint some times.

16. GIS Standards and Operation:
• Understand the system requirements.
• Standards organizations such as Open Geospatial Consortium(OGC),the
U.S. Federal Geographic Data Committee(FGDC),the International
Organization for Standardization(ISO).

17. Methods for testing spatial relation
between geometry
• Equal • Contain
• Disjoint • Overlap
• Intersect • Relate
• Touch
• Cross
• Within

18. Methods for spatial analysis
• Distance
• Buffer
• ConvexHull
• Intersection
• Union
• Difference
• SymDifference

19. Example:
create table STATES
(
StateName varchar(20) primarykey,
Shape varchar(20),
Country reference COUNTRIES
);
Select StateName from STATES where
(AREA(Shape)>500000);
19

20. GIS application and software
• Used by specific organization and disciplines such as the military and
government
• Expanded to real-estate , city planning,
navigation,transportation,emergency services,etc.
• ArcGIS provided map-making, analysis,data collection,etc.

21. Future work in GIS
• Data Sources
• Standards
• New Architecture
• Mobile GIS
• Temporal GIS
• Modeling multiple aspect of GIS
• Common Notation
• Specialized DBMS for GIS

22. THANK YOU !!!