This document outlines the theoretical framework for how data is transformed in a geographic information system (GIS). It discusses four main stages of transformation: (1) data is selected from the real world, (2) input into the GIS, (3) manipulated and stored within the system, and (4) output from the system. Each stage may involve several operations on the data. Understanding how these transformations work forms the theoretical basis for modeling and representing real-world objects and information in a GIS.

1. THEORETICAL
FRAMEWORK FOR GIS
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GIS Lecture Series

2. What You will learn
• How data are transformed and held as a model
of real world
• Different types of transformations that data is
subjected to in
– Conventional Map Making process
– GIS
• Example explaining theoretical framework and
transformations in GIS

3. • Present discussion of theoretical framework is
not related to any specific software,
• But it is a model of how different processes
take place in a digital GIS environment while
producing the digital geographic(spatial)
information.

4. • The data representation here in this discussion
should not be confused with any specific type
of data structure such as raster, vector, TIN,
attribute etc.

5. • All (many) of the information systems have
the capability to apply principal
transformations on the data to some extent for
converting it into information.
• But, only those software which have some
capacity for input, manipulate and output the
digital spatial data in some format are
considered as GIS.

6. • The GIS approach of transforming data into
information is based on the cartographic
principles.
• Cartography (cartographers) provide the
understanding of relationships between the real
world and map as a model.
• The relationships helps in understanding
various transformations the real world data
takes to become a map.

7. • Process of analog map production may be
modelled as a series of transformations
between real world data, raw data, the map and
the final map image.

8. • The significance of these transformations is
that they control the amount of information
transmitted from one stage to the next.
• The cartographer's task is to devise the very
best approximation to an 'ideal' transformation
involving a minimum of information loss.
• In GIS, the approach is extended to convert the
paper map into a digital map (digital
information).

9. • In GIS, the approach is extended to convert the
paper map into a digital map (digital
information).
• In the context of GIS, an additional
transformation stage which sits entirely within
the GIS is added.

10. • In the first transformation (T1 ), data are selected
from the real word, as for example, surveying
measurements or census data.
• These are then input for the GIS in some form
(T2) to provide the basis for its digital map
representation of the real world.
• Within the system, a vast range of manipulation
operations are available to further transform the
data and store the results (T 3), and these may be
communicated as tabulated or graphic images by
means of a hardcopy or screen (T4).

12. • Each of these transformation stages may actually
involve several physical operations on the data.
• T1 may involve both collection and aggregation,
and T 3 will almost always consist of a whole
series of data-processing operations.
• If the 'thematic and spatial' charateristics which
are very important are to be understood, it is
necessary for us to carefully consider the way in
which these four transformations may effect the
digital representation of the real-world objects

13. • The concept and understanding of the above
mentioned transformation forms the theoretical
frame work of GIS.
• The understanding of GIS data manipulation,
and obtaining information from real world data
using a GIS model is based on the
understanding of theoretical framework, which
forms the basis of GIS modelling the real
world.

14. • Thankyou.