Data Development
Paint the Town produces forecasts at a much more detailed level than previous forecasting tools. Parcel data is used to determine which areas are available for development, which areas are currently developed, and which are protected or non-developable — such as parks or floodplain.
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Figure 1. Polygon with Spike |
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Figure 2. Large Parcels |
This information, plus data from future land use plans and other information are merged into a new dataset which creates simpler (and fewer) polygons than parcel data, yet retains much of the detailed land use information from the original parcel data.
Parcel data cannot be directly used in the software because of the large number of polygons. Also, the software will not accept common data irregularities, such as spikes, slivers and discontinuous multipart polygons.
Figure 1 shows an example of a parcel polygon containing a spike which is an unacceptable data error in the Paint the Town software.
Figure 2 is a parcel-size classification map that shows another problem with using parcel data in Paint the Town. Many of the vacant parcels in Johnson County are too large to be developed at one time, or with one land use type.
The simpler polygons used in Paint the Town were created by first overlaying vector grid cells — 50 ft. cells in developed areas and 500 ft. (or 5.6 acre) cells in undeveloped areas — on top of the parcel data and assigning to the grid cell the land use of the parcel “underneath” the cell centroid. Then, adjacent cells with identical land uses were merged to minimize the polygon count. There are approximately 800,000 such polygons in the Kansas City metropolitan region.
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Figure 3. Parcel Detail Retained |
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Figure 4. Merged Grid Cells |
In Figure 3, one can see how the original land use detail is retained when comparing 50 ft. grid cells (green squares) with parcel boundaries (blue outlines).
Figure 4 shows how 50-ft grid cells have been merged where they share current land use, future land use, and decade of development. Vacant areas are divided into 500-ft grid cells.