Table Of ContentST/ESA/STAT/SER.F/79
Department of Economic and Social Affairs
Statistics Division
Studies in Methods Series F No. 79
Handbook on geographic
information systems and
digital mapping
United Nations
New York, 2000
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NOTE
The designations used and the presentation of material in this publication do not imply the
expression of any opinion whatsoever on the part of the Secretariat of the United Nations concerning the
legal status of any country, territory, city or area, or of its authorities, or concerning the delimitation of
its frontiers or boundaries.
The term “country” as used in this publication also refers, as appropriate, to territories or areas.
The designation “developed regions” and “developing regions” are intended for statistical
convenience and do not necessarily express a judgment about the stage reached by a particular country
or area in the development process.
Symbols of United Nations documents are composed of capital letters combined with figures.
Mention of such a symbol indicates a reference to a United Nations document.
______________________
ST/ESA/STAT/SER.F/79
UNITED NATIONS PUBLICATION
SALES No. 00.XVII.12
ISBN 92-1-161-426-0
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Preface
The United Nations has, over the years, issued a b) support data collection and help monitor census
series of handbooks and technical reports intended to activities during enumeration; and
assist countries in planning and carrying out
improved and cost-effective population and housing c) facilitate presentation, analysis and dissemination
censuses. These handbooks and reports have been of census results, during the post-enumeration
reviewed from time to time to reflect new phase.
developments and emerging issues in census taking.
The present handbook is part of a series of handbooks The publication is divided into three chapters.
that have been developed to assist countries in their The structure reflects as closely as possible the census
preparation for the 2000 and future rounds of cycle. The first chapter gives an introduction and
censuses. The other handbooks in the series include: overview of geographic information systems and
digital mapping. The second chapter discusses, inter
(a) Handbook on Population and Housing Census alia, cost-benefit analysis of an investment in digital
Editing (ST/ESA/STAT/SER.F/82); cartography and GIS, plans for census cartographic
(b) Handbook on Census Management for Population process, digital map database development, quality
and housing censuses (ST/ESA/STAT/SER.F/ assurance, database maintenance, and use of GIS
83). during census enumeration. The last chapter describes
The Principles and Recommendations for the role of GIS and digital mapping in the post-censal
Population and Housing Censuses – Revision 1 phase and deals with tasks after the census and during
(United Nations, 1998) make reference to the the inter-censal period, such as database maintenance,
emergence of new technologies for census dissemination of geographic census products, and
operations. One of the new technologies is the geographic analysis of census data.
application of geographic information systems (GIS)
and digital mapping in censuses since technical The handbook is as comprehensive as possible
developments in computer hardware and mapping without overloading the reader with too much
software have already encouraged many statistical technical presentation, which is dealt with in the
and census offices to move from traditional annexes. The annexes provide technical aspects such
cartographic methods to digital mapping and as an overview of GIS, coordinate systems and map
geographic information systems. projections, geographic data modelling, and thematic
mapping.
The purpose of this publication is to assist
countries by providing a reference document that During the revision process, the United Nations
focuses on digital mapping aspect when conducting Secretariat consulted cartographic and GIS experts
population and housing censuses. Traditionally, the representing all regions of the world to review and
role of maps in the census has been to support finalize the handbook. The handbook also presents,
enumeration and to present aggregate census results some examples of country practices in the application
in cartographic form. In addition to enabling more of GIS and digital mapping used in censuses
efficient production of enumerator maps and thematic contributed by some of these experts. The present
maps of census results, GIS now plays a key role in publication was drafted by Mr. Uwe Diechmann, a
census data dissemination and in the analysis of consultant for the United Nations Statistics Division.
population and household data.
In particular, the objectives of the publication are
to provide guidance to countries on how to:
a) ensure consistency and facilitate census
operations, particularly at the pre-
enumeration phase;
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Contents
Chapter Page
Abbreviations and acronyms......................................................................................................................viii
I. Introduction and overview......................................................................................................................1
A. The role of maps in the census.............................................................................................................1
B. The mapping “revolution” ...................................................................................................................1
C. Increasing demand for local area statistical data..................................................................................2
D. Scope, purpose and outline of the handbook........................................................................................3
II. Pre-enumeration......................................................................................................................................5
A. Introduction..........................................................................................................................................5
B. Cost-benefit analysis of an investment in digital cartography/geographic...........................................5
1. Costs .......................................................................................................................................6
2. Benefits...................................................................................................................................10
(a) Efficiency benefits.....................................................................................................10
(b) Effectiveness benefits................................................................................................11
3. Critical success factors............................................................................................................13
C. Planning the census cartographic process..........................................................................................13
1. Overview................................................................................................................................13
2. Needs assessment and determination of mapping options.....................................................14
(a) User needs assessment...............................................................................................14
(b) Determination or output products..............................................................................15
(c) Mapping options........................................................................................................15
3. Institutional issues in setting up a digital mapping program.................................................16
(a) Staffing, responsibilities and training requirements...................................................16
(b) Institutional cooperation............................................................................................18
(c) Equipment and software for census mapping applications........................................20
(d) Decentralization of census mapping activities...........................................................25
(e) Timing of census mapping activities..........................................................................25
(f) Process control..........................................................................................................27
4. Definition of the national census geography..........................................................................27
(a) Administrative hierarchy............................................................................................27
(b) relationship between administrative and other statistical reporting
or management units......................................................................................................28
(c) Delineation of enumeration areas...............................................................................29
(d) Delineation of supervisory (crew leader) areas..........................................................30
(e) Consistency with past censuses..................................................................................30
(f) Coding scheme...........................................................................................................30
5. Geographic information system database design....................................................................31
(a) Scope of mapping activities........................................................................................31
(b) Implementation choices..............................................................................................35
(c) Definition of the geographic information system database structure..........................36
(d) Metadata development................................................................................................40
(e) Data quality issues......................................................................................................41
(f) Tiling of national territory into operational zones.......................................................44
(g) The digital administrative base map...........................................................................44
(h) Dealing with disjoint area units..................................................................................44
(i) Computing areas.........................................................................................................45
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D. Digital map database development..........................................................................................................46
1. Overview........................................................................................................................................46
2. Cartographic data sources for enumeration area mapping (secondary data acquisition)................48
(a) Types of maps required...............................................................................................48
(b) Inventory of existing sources.....................................................................................49
(c) Importing existing digital data...................................................................................49
3. Additional geographic data collection (primary data acquisition)..................................................50
(a) Field techniques overview..........................................................................................50
(b) Global positioning systems.........................................................................................50
(c) Aerial photography.....................................................................................................55
(d) Satellite remote sensing..............................................................................................60
4. Geographic data conversion............................................................................................................63
(a) Conversion of hard-copy maps to digital data............................................................63
(b) Digitizing....................................................................................................................63
(c) Scanning.....................................................................................................................65
(d) Editing........................................................................................................................68
(e) Constructing topology................................................................................................68
5. Digital map integration...................................................................................................................69
(a) Introduction................................................................................................................69
(b) Georeferencing...........................................................................................................69
(c) Projection and datum change.....................................................................................70
(d) Coding.......................................................................................................................71
(e) Integration of separate map segments........................................................................71
E. Quality assurance, enumeration area map production and database maintenance...................................72
1. Overview........................................................................................................................................72
2. Draft map production and quality assurance procedures...............................................................73
(a) Matching boundaries and attribute files and printing overview maps........................73
(b) Quality assurance.......................................................................................................73
(c) Verification by local authorities and final administrative unit check.........................74
3. Enumeration area map printing......................................................................................................74
F. Use of geographic information systems during census enumeration......................................................78
1. Use of digital maps for census logistics..........................................................................................78
2. Monitoring progress of census operations......................................................................................78
3. Updating and correction of enumeration area maps during enumeration.......................................79
III. Post-enumeration 81
A. Introduction.............................................................................................................................................81
B. Tasks after the census and during the inter censal period.......................................................................81
1. Immediate tasks..............................................................................................................................81
(a) Incorporating updates and changes suggested by enumerators..................................81
(b) Reconciliation of collection units and tabulation or statistical units..........................81
2. Database maintenance.....................................................................................................................83
(a) Database archiving.....................................................................................................83
(b) Database maintenance: advantages of a continuous mapping program.....................83
C. Dissemination of geographic census products..........................................................................................83
1. Planning data dissemination...........................................................................................................83
2. Required products...........................................................................................................................84
(a) Equivalency and comparability files..........................................................................84
(b) Reference map library................................................................................................85
(c) Gazetteers and centroid files......................................................................................85
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3. Thematic maps for publication.......................................................................................................85
(a) The power of maps.....................................................................................................85
(b) Thematic mapping of census data..............................................................................86
(c) Thematic map production and publication issues......................................................87
(d) Output options...........................................................................................................88
4. Digital geographic databases for dissemination..............................................................................92
(a) Definition of data content..........................................................................................93
(b) Data formats..............................................................................................................93
(c) Documentation and data dictionaries.........................................................................95
(d) Preparation of deliverables........................................................................................96
(e) Legal and commercialization issues...........................................................................96
(f) Marketing of digital map products.............................................................................99
(g) Outreach...................................................................................................................100
5. Digital census atlases....................................................................................................................100
(a) Static census atlases...........................................................................................................100
(b) Dynamic census atlases.....................................................................................................101
6. Internet mapping...........................................................................................................................102
(a) Server-side approaches............................................................................................103
(b) Client-side approaches.............................................................................................104
(c) Hybrid approaches...................................................................................................104
(d) Opportunities for census data distribution...............................................................104
D. Advanced topics: geographic analysis of census data............................................................................106
1. Urban area definition/delineation.................................................................................................106
2. Reconciling small area statistics with similar information from previous censuses.....................106
(a) Aggregation of old enumeration areas to new district boundaries...........................107
(b) Areal interpolation where boundaries are incompatible..........................................108
(c) Temporal geographic information system databases...............................................112
3. Population data by grid cells.........................................................................................................112
Bibliography and references.........................................................................................................................115
Annex I. Geographic information systems..................................................................................................121
Annex II. Coordinate systems and map projections.....................................................................................133
Annex III. Data modelling............................................................................................................................145
Annex IV. Example of a data dictionary for distribution..............................................................................149
Annex V. Thematic map design...................................................................................................................153
Annex VI. Glossary......................................................................................................................................183
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Abbreviations and acronyms
ASCII American Standard Code for GLONASS Global Navigation Satellite
Information Interchange System
BMP Bitmap GPS Global Positioning System
BPS Bits per second HLS Hue lightness saturation
BUCEN United States Bureau of the HPGL Hewlett-Packard graphics
Census language
CAD/CADD Computer-aided HTML Hypertext Markup Language
design/Computer-Aided Design HVS Hue value saturation
and Drafting
ISO International Organization for
CCD Charge-coupled device Standardization
CD-ROM Compact disk-read only memory JPEG Joint Photographic Experts Group
CGM Computer graphics metafile LAN Local Area Network
CLA Crew leader area MB Megabyte
CMY Cyan magenta yellow NSDI National spatial data infrastructure
CMYK Cyan, magenta, yellow and black PDF Portable document format
CSDGM Content Standards for Digital PES Post enumeration survey
Geospatial Metadata
RDBMS Relational database management
DEM Digital elevation model system
DGPS Differential global positioning RGB Red, green and blue
system
SPOT Satellite pour l'observation de la
DHS Demographic and Health Survey terre
DPI Dots per inch SQL Structured query language
DVD Digital video/versatile disk TCP Transmission Control Protocol
DXF Drawing exchange format TIFF Tagged image file format
EA Enumeration area UPS Uninterruptable power supply
ED Enumeration district UTM Universal Transverse Mercator
ESRI Environmental Systems Research VPF Vector product format
Institute
WMF Windows metafile
GB Gigabyte
WWW World Wide Web
GIF Graphics interchange file
GIS Geographic information system
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Handbook on geographic information systems and digital mapping 1
I. Introduction and Overview
A. The role of maps in the census • Maps make it easier to present, analyse and
disseminate census results (post-enumeration).
1.1. Many of the changes to the Principles and Cartographic presentation of census results
Recommendations for Population and Housing provides a powerful means for visualizing the
Censuses (United Nations, 1998) reflect the emergence results of a census. This supports the identification
of new technologies for census operations. Significant of local patterns of important demographic and
technical developments will undoubtedly benefit census social indicators. Maps are thus an integral part of
data capture, processing and distribution. In the policy analysis in the public and private sectors.
cartographic domain, advances in computer hardware
1.4. The remaining sections of the introduction will
and mapping software have already encouraged many
provide a brief overview of the objectives of the
statistical and census offices to move from traditional
handbook. The following section summarizes the rapid
cartographic methods to digital mapping and geographic
developments in digital mapping that have also been the
information systems (GIS) (see, e.g., Rhind, 1991; Ben-
motivation for preparing the present handbook; the next
Moshe, 1997; and United Nations, 1997a).
section discusses why census offices are under
1.2. Traditionally, the role of maps in the census has increasing pressure to provide timely census data in
been to support enumeration and to present aggregate geographically referenced form. Finally, the contents of
census results in cartographic form. Cartographic the handbook are summarized in brief.
automation has greatly expanded this role. In addition to
enabling more efficient production of enumerator maps
B. The mapping “revolution”
and thematic maps of census results, GIS now plays a
key role in census data dissemination and in the analysis 1.5. People have used maps for centuries to represent
of population and household data. their environment. Maps are used to show locations,
distances, directions and the size of areas. Maps also
1.3. Mapping has been an integral part of census taking
display geographic relationships, differences, clusters
for a long time. Very few enumerations during the last
and patterns. Maps are used for navigation, exploration,
several census rounds were executed without the help of
illustration and communication in the public and private
detailed maps. In general terms, digital mapping serves
sectors. Nearly every area of scientific enquiry uses
several purposes in the census process:
maps in some form or another. Maps, in short, are an
• Maps ensure consistency and facilitate census indispensable tool for many aspects of professional and
operations (pre-enumeration). academic work.
The census office needs to ensure that every
1.6. Cartography has been affected by the information
household and person in the country is counted, and
revolution somewhat later than other fields. Early
that no households or individuals are counted twice.
computers were good at storing numbers and text.
For this purpose, census geographers partition the
Maps, in contrast, are complex, and digital mapping
national territory into small reporting units. Maps
requires large data storage capacity and fast computing
thus provide an essential control device that
resources. Furthermore, mapping is fundamentally a
guarantees consistency and accuracy of the census.
graphical application, and early computers had limited
• Maps support data collection and can help monitor graphical output capabilities. The earliest mapping
census activities (during enumeration). applications implemented on computers in the 1960s did
During the census, maps ensure that enumerators not therefore find wide application beyond a few
can easily identify their assigned set of households. government and academic projects. It took until the
Maps are also issued to census supervisors to 1980s for commercial geographic information systems
support planning and control tasks. Maps can thus to reach a level of capability that would lead to their
also play a role in monitoring the progress of rapid adoption, for example, in local and regional
census operations. This allows supervisors to government, urban planning, environmental agencies,
identify problem areas and implement remedial mineral exploration, the utility sectors and commercial
action quickly. marketing and real estate firms.
Handbook on geographic information systems and digital mapping 2
1.7. GIS has benefited greatly from developments in Digital techniques allow better management, faster
various fields of computing. Better database software retrieval and improved presentation of such data. There
allows the management of vast amounts of information has, therefore, always been a close linkage between
that is referenced to digital maps. Computer graphics geography and statistics—as reflected, for instance, by
techniques provide the data models for storage, retrieval the fact that the national statistical and mapping
and display of geographic objects. Advanced agencies in many Latin American countries are housed
visualization techniques allow us to create increasingly under the same roof (see, also, EUROSTAT, 1996).
sophisticated representations of our environment. GIS This close integration of GIS in statistical applications
data display functions go far beyond static two- yields large benefits to national statistical offices as it
dimensional displays and provide animation and three- reduces the cost and time required to collect, compile
dimensional modelling capabilities. Just as the input of and distribute information. GIS allows the statistical
textual information is facilitated by optical character office to produce a greater number of services, thereby
recognition, fast, high-resolution scanning and considerably increasing the return on investment in data
sophisticated software speed up map data conversion collection.
that previously relied exclusively on manual digitizing.
1.8. New information sources also shorten the time from C. Increasing demand for local area
project planning to operational database. The most statistical data
important recent developments have been in navigation
1.12. The benefits of geographic data automation in
and remote sensing. The Global Positioning System
statistics are shared by the users of census and survey
(GPS) has revolutionized field data collection in areas
data. The data integration functions provided by GIS,
ranging from surveying to environmental monitoring
which allow the linking of information from many
and transportation management. A new generation of
different subject areas, have led to a much wider use of
commercial, high-resolution satellites promise pictures
statistical information. This, in turn, has increased the
of nearly any part of the earth's surface with enough
pressure on statistical offices to produce high-quality
detail to support numerous mapping applications. The
spatially referenced information for small geographic
cost of precision digital mapping will fall significantly
units. The types of applications for such data are almost
as a result of the close integration of GPS techniques
limitless. Some examples are:
and digital cameras in aerial photography.
• Planning of social and educational services. A
1.9. Similar advances are occurring in the areas of
main task of local and regional government is to
geographic data dissemination. All major GIS vendors
ensure that all parts of the country have equal
now provide the tools to make geographical databases
access to government services such as health care
accessible via the Internet on the World Wide Web
and education. Small area census data on age and
(www). Government agencies at all levels are
social characteristics allow planners to forecast
embracing this technology to provide access to vast
demand for various services. In combination with
amounts of spatial information to the public cheaply and
GIS data on transport infrastructure, this
quickly. The Internet is likely to replace printed maps
information allows better distribution of resources
and digital media as the most important means of data
among existing service centres and more rational
distribution.
decisions concerning the location of new facilities.
1.10. Internet mapping programs are one indication • Poverty analysis. In countries where income or
that the tools to utilize digital spatial information are consumption data are not collected during a census,
constantly becoming cheaper and easier to use. While household characteristics are an important indicator
high-end GIS packages still require considerable of the welfare of various population groups. Small
training to be used effectively, desktop mapping area census data, in combination with spatially
packages are no more complicated to use than standard referenced information on infrastructure and agro-
business software. Digital mapping is also becoming ecological conditions, can be used to estimate
more closely integrated in standard computer poverty incidence and the location of poor
applications such as spreadsheet, graphics and business communities. This information improves targeting
management software. of poverty alleviation schemes by channelling
resources to areas of greatest need while avoiding
1.11. Statistical offices were some of the early
leakage of subsidies to non-poor communities.
adopters of GIS. Population, social and economic
statistics are the foundation of public planning and • Utility service planning. Private and public water,
management. The spatial distribution of socio-economic gas, electricity and telecommunications utilities not
indicators guides policy decisions on regional only use GIS to manage their physical
development, service provision and many other areas. infrastructure, they also use spatial analysis of
