A Third Dimension
The capacity to render data into three dimensional surfaces has significantly enhanced the ability of scientists to detect spatial patterns. Three dimensional (3D) visualization of disparities in an urban setting may allow managers to better understand them, as well as aid in the dissemination of information to broader audiences. In 3D, median income distributions and the density of children within Tacoma, WA reveal patterns that may have otherwise been lost in two dimensions.
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3D Visualization of Demographic Distributions in Tacoma, Washington
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Click the 3D image for a printable version of this analysis
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Topography in 3D
A 2D raster benefits from hillshade effects (Figure 1). When elevation data is used to define base heights, this 2D raster is transformed into a 3D surface (Figure 2). Streets may then be “floated” onto the 3D topographic surface, conforming to the true topography of the area of interest. This process allow for the fine scale visual analysis of topographic features (Figure 3).
Figure 1: 2D Raster of Old Town Tacoma.
Figure 2: 2D streets prior to “draping” over 3D rendered topography of Old Town Tacoma.
Figure 3: 3D topography and streets of Old Town Tacoma.
The density of children 10 and under per square mile was calculated using 2010 US Census data
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Census blocks were then converted into points and the density of children interpolated using inverse distance weighting (Figure 6)
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Classifications were based on ½ standard deviation
(Min: 0, Max: 13,203, Mean: 784, Std. Dev: 982)
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Child density was then visualized in 3D after adjustment of vertical exaggeration to minimize the 2D surface (Figure 7)
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High densities of young children occur inland (background) and do not appear to occur where median incomes are highest (above)
Child Density Distribution
Figure 6: 2D IDW interpolated surface distribution of the density of children 10 and under in Tacoma Washington.
Figure 7: 3D rendering of the density of children10 and under in Tacoma, Washington.
Children 10 and under per square mile
Median Income Distribution
US Census Median Incomes for 2013 were joined to Tacoma US census block groups
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Census blocks were then converted into points and income distributions interpolated using inverse distance weighting (Figure 4)
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Classifications were based on ½ standard deviation.
(Min: 11,659, Max: 139,374, Mean: 53,935, Std. Dev: 21,472)
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Median incomes were then visualized in 3D after adjustment of vertical exaggeration to minimize the 2D surface (Figure 5)
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Median incomes are higher along the water front (foreground) of Tacoma.
Figure 4: Centroid points used for IDW interpolated surface distribution of median income in Tacoma Washington in 2D.
Figure 5: 3D rendering of median income distributions in Tacoma, Washington.
Median income per census block ($)
Resources/References
Cartographer/GIS Analyst: Tracie S. Barry Contact: barryts@uw.edu
Created: April 12, 2019 Software: ArcMap/ArcScene 10.6.1
Projected Coordinate System:NAD 1983 HARN StatePlane Washington South FIPS 4602 Feet
Data Sources: UWT GIS Certificate Program, 2016 US Census, American Fact Finder
Pierce County Open GeoSpatial Portal
For a printable cartographic version of the Median Income Distribution Analysis click the image below:
