inferring areal geographies of named populated places in connecticut patrick mcglamery university of...

Inferring areal geographies of named populated places in Connecticut

Patrick McGlamery

University of Connecticut Libraries

The ppl feature type in GNIS

ppl (populated place) – place or area with clustered or scattered buildings and a permanent human population (city, settlement, town, village).

Satisficing Connecticut's ppls

“Satisficing has been defined by Simon (1979) as a psychological form of the law of diminishing returns – we do not seek optimal solutions to certain problems because the costs are too high, so we settle for solutions that are satisfactory given the cost.”

Only towns, the primary unit of civil administration in Connecticut, have boundaries. All of the ppls are represented as points. Therefore areas need to be determined for these places in order to generate a footprint.

Named populated places in Connecticut

169 town civil divisions

718 unbounded populated places,

“ppl”

Inferring areas for GNIS ppls

Working from classed 1995 30m cell satellite imagery and ppls from the GNIS, areal boundaries were determined based on five Land Use / Land Cover classes which describe a built environment.

• Commercial & Industrial

• Residential

• Rural Residential

• Tree & Turf Complex

• Tree & Grass Complex

Land Use / Land Cover

Land Use / Land Cover with Town boundaries

Land Use / Land Cover with Town boundaries and ‘ppl’

Land Use / Land Cover with built

environmentspopulation

classes aggregated and joined

to ppl

Ppl with no area

Process observations

• Successful inferences resulted in a single ppl point per polygon. (258 of 718)

• Unsuccessful inferences resulted in:

– Multiple ppl points per polygon (193 of 718)

– Ppl points with no polygon (267 of 718)

All ppls718

Successfully inferred ppl areas

258 of 718

Unsuccessfully inferred ppl areas

267 of 718

Multiple inferences of ppl

areas193 of 718

Multiple ppl points per polygon

Are a result of urban sprawl. Ursprawl in Connecticut creates a continuous urban landscape along the coast and up the I91 corridor.

The ppls in the sprawl may still be discrete places, or may have faded from the public notion of a named place and reside only on a map.

Podunk, a nowhere place in Connecticut.

The ppl is off-set from the crossroads and from the built

environment.

In fact, Podunk appears to really be in the sticks.

Or, the Town of Guilford, which is a civil division and

is large.

But the populated place of Guilford, is not a ppl and so

is not an inferred area.

ppl in GNIS, but no built environment

or, built environment, but no ppl.

Conclusions

• Bounding boxes of point data (ppl) are points.

• Spatial data can be processed to satisfice footprints in Connecticut, but requires local authentication.

• We cannot assume, a priori, that the GNIS reflects named

places in Connecticut.