Space Informatics Lab - University of Cincinnati USER GUIDE SocScape V 1.0 September 2014
1. Introduction SocScape (Social Landscape) is a GeoWeb-based tool for exploration of patterns in high resolution (90 m) demographic grids covering the entire conterminous United States. These grids have been calculated from Census 1990 and 2000 data using dasymetric modelling with land cover as auxiliary variable. National Land Cover Datasets 1992 and 2001 provided 30 m resolution land cover data. Methodology to obtain demographic grids is described in: A. Dmowska and T.F. Stepinski (2014) High resolution dasymetric model of U.S demographics with application to spatial distribution of racial diversity. Applied Geography 53, pp 417-426. At present SocScape includes two demographic variables, population density and racial diversity. There are altogether six demographic layers, three for each variable. Within each variable there are two layers covering the year 2000 labeled NLCD and retrofit, respectively. The NLCD layer is obtained using NLCD 2001 data for dasymetric modelling, whereas the retrofit layer is obtained using retrofit 2001 data. See http://www. mrlc.gov/ for distinction between the two datasets. There is only a retrofit-based layer for 1990. The retrofit-based layers should be used only for 1990-2000 demographic pattern change analysis. SocScape has been developed in the Space Informatics Lab (sil.uc.edu) at the University of Cincinnati and is available at http://sil.uc.edu/webapps/socscape_usa/ 2
2. Opening Screen 2.1 - The main window On opening the center of the screen shows Google Hybrid map of the U.S. Major features of an application are labeled by letters A to G in the figure above and discussed below. 2.2 - Map layers (labels A and B) This panel shows all layers available to SocScape. The layers are divided into two categories: - Google layers; these auxiliary layers are provided for spatial reference - Demographic layers are the 90 m grids of population density and racila diversity. 3
2. Opening Screen 2.3 - Scale and navigation (label C) Map navigation is provided by panning and zooming. In order to pan the map press the left mouse button and drag the map. Use mouse wheel to zoom in and out. Zooming into a selected rectangle is accomplished by pressing Shift button and using mouse to indicate an approximate area into which to zoom in. Navigation icon at the top-left part of the screen has a map scale slider and zoom-out to maximum extent button. 2.4 - Transparency (label E) Transparency slider is located at the lowerleft part of the screen. It acts on the selected demographic layer. For opacity slider to be activated a demographic layer has to be selected and highlighted by clicking the left mouse button on its name. Transparency is used for spatial reference with Google Maps 4
2. Opening Screen 2.5 - Legends (label F) When SocScape opens a legend panel is hidden. Press Legend button in the upper right corner of the main window to see a legend for the selected demographic map. To make legend to appear permanently the << button located above the legend button needs to be pressed. Population density layers are classified to 10 bins. The original, unclassified 90 m resolution population density grid for the entire U.S. can be downloaded from http:// sil.uc.edu/ (390 MB). Racial diversity layers have 33 categories. For explanation of how this classification has been obtained see the reference paper cited on page 2 of this guide. As an alternative to using a legend leftclicking the mouse on the map brings up a small window with information about the value of the selected demographic layer at a given point. 5
2. Opening screen 2.6 - Downloading map (D) The georeferenced region of the map that appears in the window can be downloaded in the GeoTIFF format for further analysis by pressing a Download map button. The size of the download is restricted to a preset limit. If larger region is desired, several smaller regions can be downloaded and put together in using GIS software. Alternatively, the entire (U.S.-wide) maps of population density (390 MB) and diversity (68 MB) can be downloaded at http://sil.uc.edu/downloads.html 2.7 - Credits (G) Clicking on the button labeled authors in the lower-right corner of the screen brings up the credits. 6
3. Demographic data layers The U.S. Census releases demographic data aggregated to areal units - irregular polygons delineated by streets, roads, creeks, or other manmade or natural boundaries. The smallest areal units of aggregation are census blocks. The area and population of a census block varies greatly. For a Web application such as SocScape it is advantageous to store demographic data in the form of a regular grid rather than irregular polygons. SocScape uses 90 m size grids of population density and racial diversity. These grids have been calculated from census blocks using dasymetric modelling technique. Dasymetric modelling applied for creation of data layers in SocScape disaggregates areal units into grid cells using land cover as auxiliary variable. Specifically, SocScape uses 30 m resolution National Land Cover Datasets or NLCD (http://www.mrlc. gov/) to sharpen the distribution of U.S. population. Two different NLCD maps are used: NLCD (National Land Cover Database 2001) which distinguishes between three different classes of developed areas (low intensity, medium intensity, high intensity) Retrofit (NLCD 1992/2001 Retrofit Land Cover Change Product) which was constructed to provide means of comparison between land cover in 1992 and 2001 but has only a single for all residential areas. The NLCD map offers a superior auxiliary variable but is available only for 2001, thus only data pertaining to 2000 Census were disaggregated using NLCD. When exploring demographic layers for 2000 please use the layers labeled NLCD. The retrofit land cover maps can be used to disaggregate both 1990 and 2000 Censuses demographic data. When exploring change between 1990 and 2000 please use the layers labeled retrofit. 7
3. Demographic data layers 3.1 - Population density maps Population density map of the San Francisco area The value of population density is assigned to each grid cell in units of people/km 2. Note that this is NOT a population count - the number of people in a cell. Population density is a floating point number not an integer. However, in order for SocScape to display the map of population density fast, the version of the map classified to only 11 bins is used. The bins are: 0, 0-1, 1-5, 5-10, 10-50, 50-100, 100-500, 500-1000, 1000-5000, 5000-10 000, more than 10 000 people/km 2. If original, unclassified grid of population density is needed it can be downloaded from http://sil. uc.edu/ (390 MB). The retrofit population density grids have the same legend as the NLCD grid. There are some small differences between 2000(NLCD) and 2000(retrofit) grids due to different maps of land cover used for disaggregation of demographic data. 8
3. Demographic data layers 3.2 - Racial diversity maps Racial diversity map of the San Francisco area Racial diversity map shows 33 categories derived on the basis of racial diversity, dominant race, and population density. With exception of adding population density, the classification follows that in S. R. Holloway, R. Wright, and M. Ellis, The Racially Fragmented City? Neighborhood Racial Segregation and Diversity Jointly Considered, The Professional Geographer, vol. 64, pp. 63 82, 2012. Racial diversity is categorized on the basis of entropy (E) with modifications made to assure agreement between obtained classes and customary notions of group dominance: low diversity class if E< 0.41 and dominant race more than 80% population. high diversity class if E> 0.79 and dominant less than 50% population. medium diversity otherwise. 9
3. Demographic data layers Low and medium diversity classes are further subdivided with respect to dominant race (Non Hispanic White, Non Hispanic Black, Asian, Hispanic, Other (Native American and Hawaiian)). Classification also takes into consideration population density: low density if population density is less than 3 people/km 2. medium density if population density is 3-30 people/km 2. high density if population density is equal to or greater than 30 people/km 2. 10
4. Using SocScape 4.1 - Examining diversity patterns in 2000 Racial diversity map of the New York area in 2000 Using Google maps navigate to the area of interest. Select either Population density 2000 (NLCD) or Population diversity 2000 (NLCD) layer and use opacity panel to set transparency. Analyze the patterns. The area of the map seen in the window can be download in a GeoTIFF format to a browser s default download folder for further analysis using ESRI ArcGIS, QGIS or other GIS software. 11
4. Using SocScape 4.2 - Examining 1990-2000 pattern change Racial diversity maps of the Fresno, California area in 1990 and 2000, respectively Using Google maps navigate to the area of interest. Select first Population diversity 1990 (retrofit) then Population diversity 2000 (retrofit) and switch between the two layers to observe change in diversity patterns. Download the maps for quantitative comparison using ESRI ArcGIS, QGIS or other GIS software. Perform similar change analysis for population density. 12
6. SocScape development team DR. TOMASz STEPInSkI Space InformatIcS lab, university of cincinnati 215 Braunstein Hall Cincinnati, OH 45221, USA stepintz@uc.edu DR. AnnA DMOWSkA Space InformatIcS lab, university of cincinnati 219 Braunstein Hall Cincinnati, OH 45221, USA dmowskaa@ucmail.uc.edu DR. PAWEL netzel Space InformatIcS lab, university of cincinnati 219 Braunstein Hall Cincinnati, OH 45221, USA pawel@netzel.pl 13