Handbook on geographic information systems and digital mapping

[Pages:205]Department of Economic and Social Affairs Statistics Division

Studies in Methods

ST/ESA/STAT/SER.F/79

Series F No. 79

Handbook on geographic information systems and digital mapping

United Nations New York, 2000

- i -

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

- ii-

Preface

The United Nations has, over the years, issued a series of handbooks and technical reports intended to assist countries in planning and carrying out improved and cost-effective population and housing censuses. These handbooks and reports have been reviewed from time to time to reflect new developments and emerging issues in census taking. The present handbook is part of a series of handbooks that have been developed to assist countries in their preparation for the 2000 and future rounds of censuses. The other handbooks in the series include:

(a) Handbook on Population and Housing Census Editing (ST/ESA/STAT/SER.F/82);

(b) Handbook on Census Management for Population and housing censuses (ST/ESA/STAT/SER.F/ 83). The Principles and Recommendations for

Population and Housing Censuses ? Revision 1 (United Nations, 1998) make reference to the emergence of new technologies for census operations. One of the new technologies is the application of geographic information systems (GIS) and digital mapping in censuses since technical developments in computer hardware and mapping software have already encouraged many statistical and census offices to move from traditional cartographic methods to digital mapping and geographic information systems.

The purpose of this publication is to assist countries by providing a reference document that focuses on digital mapping aspect when conducting population and housing censuses. Traditionally, the role of maps in the census has been to support enumeration and to present aggregate census results in cartographic form. In addition to enabling more efficient production of enumerator maps and thematic maps of census results, GIS now plays a key role in census data dissemination and in the analysis of 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 preenumeration phase;

b) support data collection and help monitor census activities during enumeration; and

c) facilitate presentation, analysis and dissemination of census results, during the post-enumeration phase.

The publication is divided into three chapters. The structure reflects as closely as possible the census cycle. The first chapter gives an introduction and overview of geographic information systems and digital mapping. The second chapter discusses, inter alia, cost-benefit analysis of an investment in digital cartography and GIS, plans for census cartographic process, digital map database development, quality assurance, database maintenance, and use of GIS during census enumeration. The last chapter describes the role of GIS and digital mapping in the post-censal phase and deals with tasks after the census and during the inter-censal period, such as database maintenance, dissemination of geographic census products, and geographic analysis of census data.

The handbook is as comprehensive as possible without overloading the reader with too much technical presentation, which is dealt with in the annexes. The annexes provide technical aspects such as an overview of GIS, coordinate systems and map projections, geographic data modelling, and thematic mapping.

During the revision process, the United Nations Secretariat consulted cartographic and GIS experts representing all regions of the world to review and finalize the handbook. The handbook also presents, some examples of country practices in the application of GIS and digital mapping used in censuses contributed by some of these experts. The present publication was drafted by Mr. Uwe Diechmann, a consultant for the United Nations Statistics Division.

-iii-

-iv-

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

-v-

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

-vi-

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

-vii-

Abbreviations and acronyms

ASCII

American Standard Code for Information Interchange

BMP

Bitmap

BPS

Bits per second

BUCEN

United States Bureau of the Census

CAD/CADD Computer-aided design/Computer-Aided Design and Drafting

CCD

Charge-coupled device

CD-ROM Compact disk-read only memory

CGM

Computer graphics metafile

CLA

Crew leader area

CMY

Cyan magenta yellow

CMYK

Cyan, magenta, yellow and black

CSDGM

Content Standards for Digital Geospatial Metadata

DEM

Digital elevation model

DGPS

Differential global positioning system

DHS

Demographic and Health Survey

DPI

Dots per inch

DVD

Digital video/versatile disk

DXF

Drawing exchange format

EA

Enumeration area

ED

Enumeration district

ESRI

Environmental Systems Research Institute

GB

Gigabyte

GIF

Graphics interchange file

GIS

Geographic information system

GLONASS

GPS HLS HPGL

HTML HVS ISO

JPEG LAN MB NSDI PDF PES RDBMS

RGB SPOT

SQL TCP TIFF UPS UTM VPF WMF WWW

Global Navigation Satellite System Global Positioning System Hue lightness saturation Hewlett-Packard graphics language Hypertext Markup Language Hue value saturation International Organization for Standardization Joint Photographic Experts Group Local Area Network Megabyte National spatial data infrastructure Portable document format Post enumeration survey Relational database management system Red, green and blue Satellite pour l'observation de la terre Structured query language Transmission Control Protocol Tagged image file format Uninterruptable power supply Universal Transverse Mercator Vector product format Windows metafile World Wide Web

v- ii-i

 ................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download