The Use of Satellite and Aerial Imagery, and Gps for Delineation of Ea Boundaries
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Interuniversity Research Center for Sustainable Development Sapienza University of Rome, Italy THE USE OF SATELLITE AND AERIAL IMAGERY, AND GPS FOR DELINEATION OF EA BOUNDARIES Roberto Bianchini 2010 WORLD POPULATION AND HOUSING CENSUS PROGRAMME Regional Workshop on International Standards, Contemporary Technologies for Census Mapping and Data Processing, Minsk, Belarus, 8-12 December 2008 Interuniversity Research Center for Sustainable Development Sapienza University of Rome, Italy Summary 1. Objectives of delineation of EA boundaries 2. Criteria for the delineation of EA boundaries 3. Main critical criterion to delineate EA boundaries 4. Principal type of maps for census operations 5. The satellite remote sensing 6. The aerial photography 7. The Global Positioning system (GPS) 8. Some conclusions 2010 WORLD POPULATION AND HOUSING CENSUS PROGRAMME Regional Workshop on International Standards, Contemporary Technologies for Census Mapping and Data Processing, Minsk, Belarus, 8-12 December 2008 Interuniversity Research Center for Sustainable Development Sapienza University of Rome, Italy 1. Objectives of delineation of EA boundaries To support the census coverage To support fieldwork operations To contribute to the statistical analysis at small area level To support sampling for statistical surveys 2010 WORLD POPULATION AND HOUSING CENSUS PROGRAMME Regional Workshop on International Standards, Contemporary Technologies for Census Mapping and Data Processing, Minsk, Belarus, 8-12 December 2008 Interuniversity Research Center for Sustainable Development Sapienza University of Rome, Italy 2. Criteria for the delineation of EA boundaries EAs has: To cover the entire country and do not have to overlap Be consistent with the administrative division and other relevant geographic units To have boundaries easily identifiable on the ground To be of approximately equal population size in order to be covered by an enumerator during data collection (Differences in the population size may occur for urban and rural areas) To be consistent (to a larger extent) with EA boundaries used in the previous census To be large enough to guarantee data privacy 2010 WORLD POPULATION AND HOUSING CENSUS PROGRAMME Regional Workshop on International Standards, Contemporary Technologies for Census Mapping and Data Processing, Minsk, Belarus, 8-12 December 2008 Interuniversity Research Center for Sustainable Development Sapienza University of Rome, Italy 3. Main critical criterion to delineate EA boundaries The main critical criterion is to estimate the approximately equal population size of EAs The three methods are: - Acquisition of administrative records (or by other sources of information) - Fieldwork activities (dwellings count) - Through remotely sensed data (satellite imagery and aerial photographs), and GPS receivers 2010 WORLD POPULATION AND HOUSING CENSUS PROGRAMME Regional Workshop on International Standards, Contemporary Technologies for Census Mapping and Data Processing, Minsk, Belarus, 8-12 December 2008 Interuniversity Research Center for Sustainable Development Sapienza University of Rome, Italy 4. Principal type of maps for census operations Small scale maps Topographic maps City maps Sketch maps High-resolution satellite images and aerial photos 2010 WORLD POPULATION AND HOUSING CENSUS PROGRAMME Regional Workshop on International Standards, Contemporary Technologies for Census Mapping and Data Processing, Minsk, Belarus, 8-12 December 2008 Interuniversity Research Center for Sustainable Development Sapienza University of Rome, Italy 4. Small scale map 2010 WORLD POPULATION AND HOUSING CENSUS PROGRAMME Regional Workshop on International Standards, Contemporary Technologies for Census Mapping and Data Processing, Minsk, Belarus, 8-12 December 2008 Interuniversity Research Center for Sustainable Development Sapienza University of Rome, Italy 4. Topographic map 2010 WORLD POPULATION AND HOUSING CENSUS PROGRAMME Regional Workshop on International Standards, Contemporary Technologies for Census Mapping and Data Processing, Minsk, Belarus, 8-12 December 2008 Interuniversity Research Center for Sustainable Development Sapienza University of Rome, Italy 4. City map 2010 WORLD POPULATION AND HOUSING CENSUS PROGRAMME Regional Workshop on International Standards, Contemporary Technologies for Census Mapping and Data Processing, Minsk, Belarus, 8-12 December 2008 Interuniversity Research Center for Sustainable Development Sapienza University of Rome, Italy 4. Sketch map 2010 WORLD POPULATION AND HOUSING CENSUS PROGRAMME Regional Workshop on International Standards, Contemporary Technologies for Census Mapping and Data Processing, Minsk, Belarus, 8-12 December 2008 Interuniversity Research Center for Sustainable Development Sapienza University of Rome, Italy 4. Manual EA delineation 2010 WORLD POPULATION AND HOUSING CENSUS PROGRAMME Regional Workshop on International Standards, Contemporary Technologies for Census Mapping and Data Processing, Minsk, Belarus, 8-12 December 2008 Interuniversity Research Center for Sustainable Development Sapienza University of Rome, Italy 4. High-resolution satellite imagery 2010 WORLD POPULATION AND HOUSING CENSUS PROGRAMME Regional Workshop on International Standards, Contemporary Technologies for Census Mapping and Data Processing, Minsk, Belarus, 8-12 December 2008 Interuniversity Research Center for Sustainable Development Sapienza University of Rome, Italy 4. Aerial photograph 2010 WORLD POPULATION AND HOUSING CENSUS PROGRAMME Regional Workshop on International Standards, Contemporary Technologies for Census Mapping and Data Processing, Minsk, Belarus, 8-12 December 2008 Interuniversity Research Center for Sustainable Development Sapienza University of Rome, Italy 5. Satellite remote sensing The spatial resolution of a satellite image is measured by the size of a pixel on the ground. The size for commercial satellites varies from the sub-one-meter of the most popular high-resolution systems such as Quickbird and Ikonos Indian Remote Sensing (IRS), SPOT’s panchromatic sensor and Landsat multi-spectral imagery are also considered high resolution systems which allow mapping at cartographic scales of 1:25,000 to 1:50,000 or smaller In September 2008, the remote sensing company GeoEye launched a sensor with a pixel size of 0.41 meters panchromatic and 1.65-meter multispectral 2010 WORLD POPULATION AND HOUSING CENSUS PROGRAMME Regional Workshop on International Standards, Contemporary Technologies for Census Mapping and Data Processing, Minsk, Belarus, 8-12 December 2008 Interuniversity Research Center for Sustainable Development Sapienza University of Rome, Italy 5. Satellite remote sensing (cont.) Only some remotely sensed data products serve census work well, namely high spatial resolution data such as Geoeye (0.41), Quickbird (0.82m), Ikonos (1m), IRS (5.8m pan), Orbimage 3 and 4 (1m), and SPOT 5 (2.5m). Ikonos was launched in 1999 and Quickbird was launched in 2001. For most census applications, 5m or better spatial resolution is needed to identify housing units. Landsat may be considered in some cases only in rural areas On line remotely sensed data such as Google Earth, GlobeXplorer, ArcGIS Explorer, and Microsoft Virtual Earth can be used as a first test, but the image quality may not be suitable for detailed EA mapping 2010 WORLD POPULATION AND HOUSING CENSUS PROGRAMME Regional Workshop on International Standards, Contemporary Technologies for Census Mapping and Data Processing, Minsk, Belarus, 8-12 December 2008 Interuniversity Research Center for Sustainable Development Sapienza University of Rome, Italy 5. Satellite remote sensing (cont.) High resolution satellite images show a level of geographic detail that is almost comparable to digital orthophoto maps created from air photos. Cloud free high-resolution images may allow counts of single housing units Aerial photography is often done on ad hoc basis, and may be more suitable for detailed surveying and mapping projects. New digital aerial photography may offer superior image quality over even high-resolution satellite imagery 2010 WORLD POPULATION AND HOUSING CENSUS PROGRAMME Regional Workshop on International Standards, Contemporary Technologies for Census Mapping and Data Processing, Minsk, Belarus, 8-12 December 2008 Interuniversity Research Center for Sustainable Development Sapienza University of Rome, Italy 5. Satellite remote sensing (cont.) Main advantages and disadvantages of high-resolution remotely sensed data: Advantages: - High spatial resolution images offer the ability to cover large areas at a level of detail sufficient for EA delineation, provided population estimates exist for the areas delineated - Imagery can permit mapping of inaccessible areas - Usually there are no restrictions for their acquisition Disadvantages: - Cloud may cover restricts image interpretation - Positional accuracy may be low without accurate ortho- rectification process 2010 WORLD POPULATION AND HOUSING CENSUS PROGRAMME Regional Workshop on International Standards, Contemporary Technologies for Census Mapping and Data Processing, Minsk, Belarus, 8-12 December 2008 Interuniversity Research Center for Sustainable Development Sapienza University of Rome, Italy 6. Aerial photography Aerial photography is obtained using specialized cameras on-board low flying planes. The camera captures the image on photographic film, or digitally Traditionally, the end products of an aerial photography project are printed photos of an area on the ground.