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تصویربرداری ماهوارهای
Four approaches to implementation have been tried: (1) using gridded PSU boundaries produced by GridSample, (2) manually segmenting gridded PSU using satellite imagery, (3) non-probability sampling (e.g. random-walk, "spin-the-pen"), and random sampling of households.
In the poorest settings, household enumeration is still routinely performed by hand with a pencil and paper [16], and satellite-enhanced enumeration has been piloted with printed maps of satellite imagery and with mobile devices [19, 20].
First, standard "top-down" gridded population datasets are generated by models that either directly disaggregate administrative population counts to grid cells using satellite imagery (e.g. land cover and nighttime lights) and other spatial data (e.g. road and building locations), or non-uniformly disaggregate population counts using complex modeling approaches.
GridSample outputs a shapefile of PSU boundaries which can be visualized in a geographic information system like QGIS(tm) or ArcGIS(tm), or overlaid on satellite imagery, for example in Google Earth(tm).
First, the segmentation approach involves sampling geographically large PSUs with probability proportionate to estimated population size, then segmenting by smaller grid cells [10] or manually delineate smaller areas using satellite imagery [6, 7, 8, 9, 10].
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