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Original Message
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Subject: GN: United Nations, GPS, and the 2010 Census survey
Date: Mon, 4 May 2009 16:36:21 -0700
Folks, this was forwarded to me. The info below comes from a .pdf file that can be found at:
[link to unstats.un.org]
You need to go look at the file to see the pictures, etc.
UNITED NATIONS SECRETARIAT ESA/STAT/AC.98/14
Department of Economic and Social Affairs 03 September 2004
Statistics Division
English only
United Nations Expert Group Meeting to
Review Critical Issues Relevant to the Planning of
the 2010 Round of Population and Housing Censuses
15-17 September 2004
New York
Integration of GPS, Digital Imagery and GIS with Census Mapping*
By
United Nations Statistics Division
DESA
* This document is being reproduced without formal editing.
2
INRODUCTION
1. The recent technological developments, including new high-resolution sensors, global
positioning systems (GPS), geographical information systems (GIS), Internet and World
Wide Web services, are revolutionizing cartography, surveying and mapping in
fundamental ways: geographic data is easily collected and combined with a variety of other
data in order to create relevant information for spatial analysis and decision making.
Geographic information, in its digital form, is indeed exchanged more rapidly, duplicated
without alteration, and easily disseminated to end-users.
2. For the past decade, the United Nations Statistics Division (UNSD) has been
promoting the development of geographical information systems for population and
demographic statistics in developing countries through technical cooperation projects
supported by the United Nations Fund for Population Activities (UNFPA), training
workshops, and technical publications. However, the statistical community in developing
countries has been slow to adopt the use of GIS, partially due to the monetary constraint
posed by commercial software and the availability of computers, base maps, satellite
imagery, work load, etc.
3. This paper outlines some developments in satellite imagery, GPS and GIS with
reference to census mapping activities, and provides some insight on the similarities
between a geographic information process and a census mapping process, therefore, it urges
for the integration of these geospatial technologies within the census mapping process. It
suggests some future actions to undertake in order to help kick-start the development of this
field in developing countries.
I. GIS, GPS AND AERIAL AND SATELLITE IMAGERY RECENT
TECHNICAL CAPABILITIES
4. The census symposium, held in New York in 2001, provided a comprehensive review
of the significant capabilities of GPS, Satellite imagery, GIS and handheld computers, and
their relevance to census mapping operations (Dekker, 2001 and Tripathi, 2001s). Hence,
our presentation will focus on the recent developments regarding these geospatial
technologies, and specifically with regard to their better integration.
5. GPS, remote sensing (including aerial photography) and GIS are technologies that are
being increasingly used in the field of data collection, including census mapping operations.
Until recently, aerial photography did play a major role in geographic data acquisition in
urban areas, and the use of satellite imagery, due to its low resolution, was limited to the
study of some phenomena like floods and urban pollution. However, recent satellite
imagery is extending its use to urban areas with the increase of its resolution to one-meter
(i.e. IKONOS satellite), its high positional accuracy, the revisit frequency of only three
days, and its GIS-readiness, despite their relative expensive cost (Montoya, 2002).
6. GPS receivers have become popular and widespread, offering a greater accuracy at a
reduced cost (a variety of units less than $500). Indeed, some cost-effective GPS can handle
real-time differential correction capable of sharpening accuracy to five meters or better.
Furthermore, GPS coordinates (waypoints) can be displayed real-time in a GIS software
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(i.e. ArcPad). GIS are becoming more powerful and friendly to use, and GPS more accurate
and cost-effective. Both are more integrated, streamlining the acquisition and processing of
coordinate data. The future of satellite positioning system looks promising, particularly
with the new system under construction, Galileo, the European system dedicated to civil
activities.
7. Beside GIS desktop and Internet GIS, Mobile GIS is becoming a reality. GIS software
has been tailored to the needs of the field operations, allowing GIS to move from the office
to the field. Indeed, improvements in handheld computers and other portable devices, as
well as greater accuracy and the reduced cost of GPS units, have made significant
contributions to the development of mobile GIS (ArcUser, January-March 2004). With
mobile GIS, it is now possible to capture, manipulate, analyze and visualize data in the field
in real time, and ground truthing has become possible1 (see a summary on an interesting
example, illustrating how advanced mobile mapping techniques were used to delineate
census enumeration areas in Dili metropolis, Timor-Leste).
s
8. Furthermore, the combination of digital video (DV), satellite imagery and GPS for the
data capture and the input of this data into a GIS for manipulation, analysis and display, is
empowering data collection and integration (for ground observations of buildings, GPS can
be used in combination with digital video). Indeed, the most significant development in
these recent years lies in the better integration of GPS, image processing and GIS systems.
Hence, collecting data in the field, and storing it in a geographic database, can obviously
improve the efficiency of the census mapping process.
II. GEOGRAPHIC INFORMATION PROCESS
9. The geographic information process consists of three stages: data acquisition, data
processing and data dissemination. As illustrated in fig. 1, geospatial technologies are
spanning through these three stages: GPS and satellite imagery, among others, are useful
tools for geographic data collection; GIS have demonstrated their powerful capacities to
enable data integration, analysis, display and dissemination. Hence, remote sensing
techniques, GPS and GIS have become ubiquitous in developing policies for integrated
management (Laaribi, 2000).
10. Geographic information is about the management of data that are geographically
referenced, in order to provide sound information for better decisions. Geographic
information is emerging as a fundamental part of the national infrastructure as important as
1 “As the newest nation of the 21st Century, (East-Timor) faces the challenges of conducting her first
population census after independence. This paper reviews the current mapping situation in East-Timor and
presents how advanced mobile mapping techniques were used to delineate census enumeration areas in Dili
metropolis. The peculiar nature of Dili, where the issue of building ownership and property boundaries
remained contentious, coupled with the non-availability of up-to-date cadastral maps; led to a combination of
remote sensing and geographic information system techniques being used to map census enumeration areas.
QUICKBIRD high-resolution satellite imagery, GPS and an Internet enabled palm-top computer running on
windows mobile operating system together with ArcPad 6.0.2 software were used to delineate census
enumeration area maps. The methodological steps undertaken for the mobile mapping technique are narrated
in this paper and the outcomes of the pilot study are compared with the traditional census enumeration area
delineation methods. (Taiwo, 2004)”
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physical infrastructure assets such as roads, telecommunications, and other public utilities.
Indeed, there is a growing awareness worldwide of the economic importance of geographic
information with applications in many sectors (regional planning, land management,
environment/natural resources, health care, transportation, urban systems, marketing
studies).
Fig. 1: Geographic information process
III. CENSUS MAPPING PROCESS
11. Census mapping operations are an essential component of a Population and Housing
Census. As illustrated in fig. 2, census processes entails three stages: pre-census, census
and post-census. In the pre-census stage(pre-enumeration), maps ensure consistency and
facilitate census operations; in the census stage, maps support data collection and help
monitor census activities (during enumeration); in post-census stage, maps make it easier to
present, analyze and disseminate census results (post-enumeration) (Handbook on
geographic information systems and digital mapping, 2000).
12. The traditional role of maps in census and survey operations consists of supporting
enumeration and presenting results in cartographic form. However, additional capabilities
of GIS, GPS and satellite imagery, such as integrated field data collection, advanced
analysis and dissemination of census data, support census activities at all three stages,
GPS
Remote Sensing
Aerial Photo.
Maps
Censuses &
Surveys
GDB
Surveying
GIS
Data
Management
Dissemination
(Information)
Data
Acquisition
5
proving that census mapping would gain by being a continuous process. Since the census is
a process, cost-benefit of census mapping should be therefore considered in this context.
13. Statistical data, including development data, such as economic or health data, concern
human activities that are geographically referenced. The geo-coding system, which is a
fundamental component in the census enumeration operations, reflects the inherent
geographic nature of census data. In other words, it constitutes the reference that gives
census units its geographic link. To sustain this link, the coding scheme (meaning that the
code is unique, and links between GIS boundaries and tabular census data), should be
flexible enough and well structured to incorporate new and future administrative divisions.
Fig. 2: Census Process
IV. STAGES OF INTEGRATION OF GIS WITH THE CENSUS MAPPING
PROCESS
14. Our observation is that a census mapping process is akin to a typical geographical
information process. There is, therefore, justification for the integration of GIS with census
mapping operations at all the stages of the process. In doing so, we go beyond the
technological approach to reflect the inherent nature of census mapping activities, which is
mainly geographic. Obviously, the integration can be undertaken gradually.
15. Therefore, we advocate a paradigm shift from a traditional mapping approach, which
is repeated for every census, to a digital census mapping approach, which is an up-to-date
and a continuous approach. We believe that an up-to-date approach will allow census
planners to rethink, inter-alia, the periodicity of census taking, the frequency of inter-censal
surveys, and eventually the way to conduct census itself (some countries are already
reconsidering the way to conduct a whole census countrywide every 10 years).
Census
(Enumeration)
Post-Cenus
(Post-enumeration)
Pre-Census
(Pre-enumeration)
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Fig. 3: GIS with census mapping: stages of integration
V. SOME CURRENT AND FUTURE ACTIONS TO PROMOTE THE USE OF
GEOSPATIAL TECHNOLOGIES WITH CENSUS MAPPING
16. The United Nations Statistics Division succeeded to ensure that the National Statistical
Offices (NSOs) of forty developing countries were provided with no-cost versions of
commercial GIS software ArcView 3.3, donated and distributed by ESRI company, under
the Global Map/GSDI Grant Program. Having a commercial software will allow NSOs to
explore satellite imagery and GPS use for statistical enumeration activities and further data
sharing and collaboration within their government ministries/departments and the private
sector.
17. The United Nations Statistics Division published in 2000 a “Handbook on
Geographic Information System and Digital Mapping”, as part of a series of handbooks
that have been developed to assist countries in their preparation for the 2000 and future
rounds of censuses. This reference document (ST/ESA/STAT/SER.F/79) is a valuable tool
for statisticians eager to understand the fundamentals of GIS and their integration within
the census mapping process. It provides its readers with many details on the matter,
including census mapping processes, digital mapping, GIS technologies and applications,
geographic data collection techniques and critical factors for a successful census planning
process.
18. While appraising the rich and useful materials provided by the handbook, some
managers and planners in National Statistical Offices would like to have specific
guidelines, allowing them to better understand how to adapt GIS technologies to census
mapping operations and how to cope with organizational and institutional issues in setting
up a digital mapping program, including the establishment of a cartographic unit. A
recommendation on the establishment of a Permanent “Cartography & Geographic
Information” Unit within the NSO should be considered.
EAs Units
GPS
Photo/Video GIS
Digital Mapping
Satellite Imagery
Pre-census Census Post-Census
(Pre-enumeration) (Enumeration) (Post-enumeration)
GIS
Digital Mapping
GIS
Internet
(i.e. Map-Server)
Administrative and
Reporting Units
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19. The use of GIS with census mapping is not widely used in developing countries,
despite the growing awareness worldwide of the economic importance of geographic
information. In order to encourage the use of geospatial technologies in statistical activities,
and help NSOs incorporate their statistical data as a fundamental component of the national
spatial data infrastructure, the United Nations Statistics Division should consider
organizing an International Conference, fully dedicated to the topic: “Integration of
Geospatial technologies with census mapping for better decisions”. Resolutions from the
Conference, advocating the use of GIS in census mapping and other statistical activities,
would help developing countries in their endeavors.
20. In order to achieve the above stated actions, workshops and technical advisory services
would be required during the 2010 round of censuses. However, these actions should be
part of a broad vision for the next decade. That’s why the UNSD is considering the
establishment of a Group of Experts to reflect on these important issues of census
mapping with GIS and formulate a plan, with the aim to lead the effort to transform censustaking
for the 2010 round of censuses, and usher in larger programs.
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REFERENCES
Dekker, Arij: Adapting new technologies to census operations. Symposium on Global
Review of 2000 Round of Population and Housing Censuses: Mid-decade Assessment and
Future prospects, United Nations Statistics Division, New York, 7-9 August
( [link to unstats.un.org]
06.htm)
Handbook on geographic information systems and digital mapping. United Nations
Publication, ST/ESA/STAT/SER.f/79. Printed in United Nations, New York, 2000
Laaribi, Amor: SIG et Analyse Multicritère. A book published in French by Hermes-
Science, Paris, 2000.
Montaya, Lorena: GIS and Remote sensing in Urban Disaster Management. 5th AGILE
Conference on Geographic Information Science, Palma (Balearic Islands, Spain), 22-25
April 2002.
Taiwo, Bolaji: Using Mobile Mapping Technique To Delineate Census Enumeration Areas
in Dili Metropolis (East-Timor), Remote Sensing and GIS Group Charles Darwin
University, Faculty of Science, 0909, Australia.
Tripathi, Raj: Mapping for the 2000 round of censuses: Issues and possible solutions.
Symposium on Global Review of 2000 Round of Population and Housing Censuses: Middecade
Assessment and Future prospects, United Nations Statistics Division, New York, 7-
9 August, 2001 ( [link to unstats.un.org]
docs/symposium_08.htm)
Taking GIS on the Road. Special Section, ArcUser, the Magazine for ESRI Software Users,
January-March 2004.
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