Transcript Building a Geographic Database and Using GIS and Spatial Analysis for Census Data Dissemination UN Statistics Division United Nations Regional Seminar on Census Data.

Building a Geographic Database and
Using GIS and Spatial Analysis for
Census Data Dissemination
UN Statistics Division
United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis
Bangkok, Thailand, 5-8 October, 2010
Outline

UN Recommendations/Census Geography Programme

Building a Geographic Database

Spatial Analysis Techniques

SALB Project

Handbook on Geospatial Infrastructure in Support of
Census Activities
United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis
Bangkok, Thailand, 5-8 October, 2010
Census Geography Programme: a continuous process
 The recommendations derived from UN EGM and Workshops on
GIS and census mapping emphasized the need for countries to
consider the census geography programme as a continuous process,
rather than the sequential mapping and dissemination operations.
 It was also emphasized that the use of and application of
contemporary geospatial technologies and geographical databases
is beneficial at all stages of population and housing census
process. Geospatial improve the efficiency in the preparatory,
enumeration, processing and dissemination phases of the census
United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis
Bangkok, Thailand, 5-8 October, 2010
Census Cycle
United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis
Bangkok, Thailand, 5-8 October, 2010
Geospatial tools at all stages
Pre-census
(Pre-enumeration)
Census
(Enumeration)
GPS
Photo/Video
Digital Mapping
Satellite Imagery
Post-Census
(Post-enumeration)
GPS/PDA
GIS
GIS
GIS
Digital
Mapping
EAs Units
Internet
(Map-Server)
Administrative and
Reporting Units
United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis
Bangkok, Thailand, 5-8 October, 2010
Admininstration
Hierarchy

Provinces
Every country has its own
specific administrative hierarchy
Districts


Definition:
A system by which the country
and each lower level set of
administrative units (except the
lowest) are subdivided to form
the next lower level.
Localities
Administrative areas for which
census data will be reported
Enumeration
areas
United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis
Bangkok, Thailand, 5-8 October, 2010
Coding Scheme
 EA: a basic geographic feature
 Need for an identifier: linking the geographic feature to the
census data (attributes) recorded for them
 EAs and administrative units: coding scheme
A unique code assigned to each EA, used in data processing
Coding scheme: scalability, flexibility, intuitiveness, compatibility


 Example of a hierarchical coding scheme
1
2
province
0
3
district
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0
1
2
locality
5
0
0
2
Enumeration area
United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis
Bangkok, Thailand, 5-8 October, 2010
4
Geocoding Concept
 “Geocoding can be broadly defined as the assignment of a
code to a geographic location. Usually however, Geocoding
refers to a more specific assignment of geographic
coordinates (latitude, longitude) to an individual address
(UN Report of the EGM on Contemporary Practices in Census Mapping and Use of GIS, 2007)
 Geo-coding: not limited to address-matching
 Geocoding covers a continuum of spatial scales: from individual
housing units to enumeration area level up to higher
administrative or national levels.
United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis
Bangkok, Thailand, 5-8 October, 2010
Implementation of an EA database
 All large operational GISs are built on geodatabases;
 Arguably the most important part of the GIS
 Geodatabases form the basis for all queries, analysis,
and decision-making.
 A DBMS, or database management system, is where
databases are stored.
United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis
Bangkok, Thailand, 5-8 October, 2010
Complete EA map with all components overlaid on one map display
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eet
Bonne Str
Robinson
Street
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Cartania
Chartes
Maptown
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Enumeration Area Map
Province:
District:
Locality:
EA-Code:
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Bessel Street
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Grinten Street
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eet
Tissot Str
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Street
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Mollweide Street
Imhof Drive
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Miller
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374
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Cassini Drive
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Goode
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Street
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Cassini Drive
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ive
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Dr
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Lambert Avenue
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ue
r Aven
to
Merca
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t
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Gall Street
kij Street
Krassows
ree
Snyder St
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Tobler Street
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Street
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Street
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eet
e Str
Clark
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Ortelius
Ptolemy
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Eckert Drive
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Main components are:
Street network,
Buildings
EA boundaries layer
Annotation,
Symbols,
Labels
Building numbers
Neatlines
Legend
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Symbols
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032
0221
00361
District
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EA-Code
Locality
Hospital
EA
N
17
Building
number
Church
School
Approximate scale
0
50
100
200m
Census 2000
National Statistical Office - July 1998
United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis
Bangkok, Thailand, 5-8 October, 2010
Components of a Hypothetical
urban EA map
Street Network
Boundaries
Street
Network
Buildings
Boundaries
Annotation
and symbols
Buildings
Anno
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358
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374
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Building
numbers
Boundaries
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62
40
Neatlines and
Annotation
and legend
symbols
Boundaries
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Building numbers
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EA
Building
number
Census
2000
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Enumeration
School
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Bangkok, Thailand, 5-8 October, 2010
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Carta
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Approxima
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Neatlines and legend
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United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis
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Province:
District:
Locality:
EA-Code:
National Statistical Office July 1998
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Church
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10
Hospital
Building numbers
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EA-Code
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Locality
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Approximate scale
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District
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Symbols
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0221
00361
N
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Neatlines and legend
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Cartania
Chartes
Maptown
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Enumeration Area Map
Province:
District:
Locality:
EA-Code:
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Ne
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Building numbers
Annotation
and symbols
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Entity-Relationship Example:
EA entity can be linked to the entity crew leader area. The table for this entity
could have attributes such as the name of the crew leader, the regional office
responsible, contact information, and the crew leader code (CL code) as primary
code, which is also present in the EA entity.
R
EA
EA-code
Area
Pop.
1-1
Crew leader area
1-N
CL-code
Name
RO responsible
United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis
Bangkok, Thailand, 5-8 October, 2010
Components of a digital geographic census database
United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis
Bangkok, Thailand, 5-8 October, 2010
Different Geographies
 A geography for data collection:

EA level or even dwelling level
 Another geography for data dissemination:

Aggregated level (confidentiality)
United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis
Bangkok, Thailand, 5-8 October, 2010
Digital Data Dissemination Users
 The wide range of potential users of disaggregated census
data means that the NSO needs to pursue a multi-leveled
digital data dissemination strategy.
 Broadly, we can distinguish between the following types of
users:
 Advanced GIS users
 Computer literate users
 Novice users
United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis
Bangkok, Thailand, 5-8 October, 2010
Uses of Graphs: Enriching the Understanding of
GIS Data Sets





Exploratory Spatial Data Analysis
Linked Maps, Graphs & Tables
Dynamic Feature Selection
Animation
Visualization over Time
United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis
Bangkok, Thailand, 5-8 October, 2010
GIS capabilities:
Visualization
United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis
Bangkok, Thailand, 5-8 October, 2010
Spatial Analysis
 Spatial Relationships (explicit -Topolgy)


Logical connections between spatial objects represented by
points, lines and polygons
e.g.,- point-in-polygon; line-line; polygon-polygon
 Geographic Database



Geographic features selection
Attributes
Structure
United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis
Bangkok, Thailand, 5-8 October, 2010
Spatial Operations
 “adjacent to”
 “connected to”
 “near to”
 “intersects with”
 “within”
 “overlaps”
 etc.
United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis
Bangkok, Thailand, 5-8 October, 2010
Spatial Analysis: Query
 select features by their attributes:

“find all districts with literacy rates < 60%”
 select features by geographic relationships

“find all family planning clinics within this district”
 combined attributes/geographic queries

“find all villages within 10km of a health facility that have high
child mortality”
Query operations are based on the SQL (Structured
Query Language) concept
United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis
Bangkok, Thailand, 5-8 October, 2010
Examples:
Id
What is
at…?
Features that
meet a set of
criteria
0012376027
Name
Population
Popdens
Num_H
H
Clinics
Limop
31838
37.5
8719
8
Population density
greater than 100
persons/sqkm?
United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis
Bangkok, Thailand, 5-8 October, 2010
“is nearest to”
• Point/point
• Which family planning clinic is
closest to the village?
• Point/line
•Which road is nearest to the
village
• Same with other combinations of
spatial features
United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis
Bangkok, Thailand, 5-8 October, 2010
“is near to”: Buffer Operations
•
Point buffer
•
Affected area around a polluting facility
•
Catchment area of a water source
United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis
Bangkok, Thailand, 5-8 October, 2010
Buffer Operations
•
Line buffer
•
How many people live near the polluted river?
•
What is the area impacted by highway noise?
United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis
Bangkok, Thailand, 5-8 October, 2010
Buffer Operations
•
Polygon buffer
•
Area around a reservoir where development
should not be permitted
United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis
Bangkok, Thailand, 5-8 October, 2010
“ is within”: point in polygon
•
Which of the cholera cases are within the
containment area
United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis
Bangkok, Thailand, 5-8 October, 2010
Spatial aggregation
 Example of Spatial aggregation:

fusion of many provinces constituting an
economic region
United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis
Bangkok, Thailand, 5-8 October, 2010
Spatial data transformation: interpolation
Example: Based on a set of station precipitation surface
estimates, we can create a raster surface that shows
rainfall in the entire region
13.5
20.1
12.7
26.0
27.2
15.9
24.5
26.1
United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis
Bangkok, Thailand, 5-8 October, 2010
Example of linear interpolation creating contours
contour lines
of elevation
can be derived
through linear
interpolation
from a
satellite image
United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis
Bangkok, Thailand, 5-8 October, 2010
Areas of influence

Commuting
distances: daily
commuters flow
United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis
Bangkok, Thailand, 5-8 October, 2010
Modelling: smoothing

Evolution of the
population
beetwen two
censuses
United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis
Bangkok, Thailand, 5-8 October, 2010
Spatial Analysis Techniques
 Cartograms

sometimes used to display
census results

The areas of the original
polygons are expanded or
contracted based on their
attribute values such as
population size or voting
habits
United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis
Bangkok, Thailand, 5-8 October, 2010
The Second Administrative Level Boundaries data
set project (SALB)

The Second Administrative Level Boundaries data set project
(SALB) has been launched in 2001 in the context of the
activities of the UN Geographic Information Working Group
(UNGIWG) and has for objective to provide access to a working
platform for the collection, management, visualization and
sharing of sub national data and information in a seamless way
from the national to the global level.

unsalb.org
United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis
Bangkok, Thailand, 5-8 October, 2010
Handbook on Geospatial Infrastructure in
Support of Census Activities (2009)
http://unstats.un.org/unsd/demogra
phic/standmeth/handbooks/default
.htm
United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis
Bangkok, Thailand, 5-8 October, 2010
Issues for consideration
 Do you have (or are you considering to have) a full
digital Geographic Database for census operations?
 Are you considering to use spatial analysis to suit specific
user needs?
 Are you partnering with other stakeholders (the public
and private sector) in order to



Build the NSDI
Work jointly on coding efforts
Produce value added products – higher demand for census
data
United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis
Bangkok, Thailand, 5-8 October, 2010
THANK YOU!
United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis
Bangkok, Thailand, 5-8 October, 2010