September 2012 GIS ToT Webinar

1. Geographic Context

3. Everything happens somewhere

4. Knowing where things happen can
help us understand why things
happen.

5. Location and Health
 There is a close link between geography and
health.

6. Question
 What are some ways that people‟s health can be
affected by geography?
Geography can affect health through landscape,
location of services, location of population in
need, human interaction with landscape

7. Medical geography
 A branch of geography that looks at the relation
between location and people‟s health
 Concepts are useful beyond medical geography
 Long history of use of geography to understand
health and disease patterns.

8. John Snow cholera map
 1854 London
 Used map to
illustrate cholera
outbreak was
centered around a
pump on Broad St
 Locking pump led to
decrease in disease

9. Malaria in India

11. Maps
 Valuable tool for displaying data and helping
people understand data and direct action
 Picture of a place which can give you a better
understanding
 When well-made, a map can give both content
and context

12. Important Properties of Maps
 When creating maps there are four factors that
are important
 Scale
 Legend
 Title
 Source
All affect the context of data displayed and how the
data is and can be INTERPRETED

13. Scale of a Map
 What is scale?
It is the „representative fraction‟ and states the
relationship between the distance on the map (such
as one centimeter) and the distance on the ground
(such as one kilometer)
 Why is scale so IMPORTANT?
The scale affects the level of detail a map shows

14. 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 general scale categories apply:
• Large-scale: 1:250 to 1:1,000
• Medium-scale: 1:1,000 to 1:10,000
• Small-scale: 1:10,000 to 1:100,000
• Very Small-scale: 1: 100,000 to above
Source: ICIMOD, 2000

15. Large Scale Small Scale
1:50,000 1:500,000

16. Scale
 What are the general rules with scale?
 Do not zoom below the scale as stated for the dataset (that is
scale at which the data was collected)
 Only integrate GIS datasets that have been collected at the
same or at a similar scale
 The maximum scale a dataset should be viewed is
approximately 100 times the Scale that is stated in the Metadata.
 For Example: Data collected at 1:5,000 should not be viewed
above 1:500,000

17. North
Title
Arrow
Scale
Bar
Legend
Data
Source

19. TYPES OF MAP

20. Concentration of Vulnerable Population-Meerut City
POPULATION DISTRIBUTION
(Using 2 Km Radius)
Graduated Circle Map
Size of symbol corresponds to data.
Advantages:
•Easily see extreme ends of the
data distribution
•Geographic patterns emerge
Disadvantages
•Can be challenging to differentiate
the middle of the distribution since
the eye can‟t easily detect small
differences in size
Map credit UHRC

21. Choropleth
Polygons are shaded to match data
distribution
Advantages:
•Easy to see geographic distribution
•Easy for most people to interpret
Disadvantages
•Polygons can hide uneven
distributions within boundaries
•If patterns/colors aren‟t chosen
wisely the map can be difficult to
interpret

22. 2002 2004
2002 2004
Continuous surface
maps
Data is distributed continuously
across space
Advantages:
• Very easy to see hot spots or
areas that deviate from other
areas
Disadvantages
• Not all data can be distributed
continuously
Depiction of Malaria incidences in Trans Yamuna Region (Allahabad D
Low High High
Low
Village-wise Slide Positivity Rate (Malaria) of Trans-Yamuna Region
2002 2004

23. Other types
With advanced software it‟s
possible to produce diagram maps
that display data using charts.
Advantages
•Effectively displays complex
information
•Lots of information on each map
Disadvantages
•Can have too much information
•Can be difficult to structure data to
produce such maps
•Requires an advanced GIS

24. Which map style should you use?
 Depends on type of data you have
 What purpose you want the map to serve
 Sometimes a matter of experimentation to find
the map style that best fits the data and purpose
of the map
It‟s important to pick the type of map that makes the
data most useful

25. Basic cartographic concepts
 Map Design
 Cartographic standards
 Generalization
 Graphic Variables
 Use of Color
 Classification of Data
 Methods of Mapping

26. Map Design
Map making is both science and art.
Maps influence people‟s perception of space. This
influence is partly because of convention and partly
because of the graphics used.
People understand the world differently, express this
understanding differently in maps, and gain different
understanding from the maps.

27. Cartographic standards
There are cartographic standards that have emerged that
make it easier to interpret and read maps.
These standards do not have to be followed, but if they aren‟t
your map may be less readable.

28. Administrative
Boundaries
--Most often black or
gray.
--The higher the
administrative unit
the thicker the line

29. Roads
Color and line styles to
represent road type with
major roads being
thicker or more
distinctively colored than
minor roads.

30. Rivers and Lakes
--Blue
--Streams dashed,
lines light blue

31. Map Design
Generalization
 Maps contain a
certain level of detail
depending upon the
scale and purpose.
 Sometimes the map
maker will need to
simplify features to
make them more
readable.

32. Use of Color
Color perception has psychological, physiological and
conventional aspects.
It has been noted that it is difficult to perceive color in small areas,
and more contrast is perceived between some colors than
between others.
In addition to distinguishing nominal categories, color differences
are also used to show deviations or gradation.
Hue
Saturation
Intensity
Source: ICIMOD

33. Use of Color
 Color blindness
 5-8% of men
 0.5% of women

34. Black-and-white
 Consider
method of
reproduction
or output of
maps

35. Making an effective map is a
matter of finding the right balance
between the limitations of the
data, the needs of the map reader
and the message you, as the map
maker, want to convey.

36. Issues to Remember
Maps can LIE!!
 Maps are just one person‟s representation of the
“real world”
 Like any source of information they can be
misleading especially when used out of context
 How maps can be deceiving
 Inappropriate Legend
 Inappropriate Scale
 Inappropriate Data Classification
Source: ICIMOD,

37. Key points
 Everything happens somewhere
 Geography is a common denominator across
human activity
 There are different types of maps. Picking the
right style means balancing the needs of the
reader, the data and the message you as
mapmaker want to convey.

38. Key points
 The mapmaker can use colors, symbology, and
generalization techniques to make maps
readable to the audience.

39. Any questions?