New Aerial Photography Sets The Stage For Updated Maps

By Andrew Gorosko

The hundreds of aerial photos that were taken of the town during optimal seasonal conditions last spring are being assembled into an electronic photomosaic that will serve as the basis for updated municipal planimetric mapping, which is a key component of the town’s geographic information system (GIS).

The new digital-format photographs that were taken from a slow-flying, six-seater aircraft that flew rigorous patterns above town are sharper and also thus provide more visual detail than previous sets of aerial photos flown for the town, said Steven Birney, the GIS software specialist for the town’s technology and GIS department.

Mr Birney expects that within a few months, the new color aerial photos will be added to the town’s GIS website to supplement a set of color aerial photos taken in 2007 and a set of black and-white aerial photos taken in 2002.

The photos provide the foundation for planimetric base mapping that depicts local properties, including structures and certain surface features, at variable scales depending upon the mapping’s magnification.

Unlike past mapping projects, which used large amounts of photographic film to produce images, the April flyover employed digital camera equipment that created computer files containing the visual data, Mr Birney said.

The photos were taken in early April, while vegetation was still dormant, thus providing overhead views unobstructed by foliage. Also, the photos were taken when shadows were minimal in order to maximize directly illuminated areas.

By having visual overlap on the images, the photos can be electronically joined to create a seamless effect, as if one gigantic photo had been taken of the town from directly above.

Individual photo frames contain about 400 megabytes of data each in the form of raw files, providing much magnifiable detail. Those images’ file sizes are reduced, as necessary, to make their use on the Internet practical.

 People who use the town’s GIS website are able to electronically switch between the planimetric mapping and the aerial photos. Comparing the aerial photos from different time periods allows the users to gauge how the land surface has changed across time. The GIS system contains a variety of information on more than 11,000 local real estate parcels.

The town’s GIS website address is newtown.mapxpress.net.

“The main purpose is [detecting] land change,” Mr Birney said of the need to produce sets of aerial photos every five years.

The aerial photography is keyed to the town’s five-year interval between its revaluations of property. In such revaluations, the town recalculates the relative market value of various properties for tax purposes.

The GIS system provides valuable reference information to various town agencies and serves a basis for municipal decisonmaking, Mr Birney said.

Mr Birney said he receives many requests for specific mapping.

Golden Aerial Surveys, a Hawleyville-based firm that produces aerial photography and photogrammetric engineering, is performing data processing on the recent set of aerial photos, Mr Birney said.

GIS is an electronic mapping system designed to provide a variety of planning information to its users through its cross-indexed, digitized format. GIS mapping collects and unifies both broad geographical information, such as the course of rivers and layout of road networks, as well as fine details, such as the location of individual utility poles and stormwater catch basins.

GIS mapping stores information on individual land parcels, roads, railroads, brooks, ponds, wetlands, open space, trails, public utilities, industrial development, and land use zones. It includes information on property boundaries, zoning boundary lines, topographic contours, tax assessments, property ownership, building sizes, and land record references, plus other data.

The information is stored in electronic “layers” that can be combined, as needed, to provide specific details for a given map.

The Technology and GIS department is producing various mapping for the Planning and Zoning Commission (P&Z) as it progresses on its decennial update of the Town Plan of Conservation and Development.

The town plan is an advisory document that provides the P&Z with general guidance in its decisionmaking. P&Z approvals or rejections of land use applications typically state whether a given application respectively adheres to or diverges from the tenets of the town plan when P&Z members state their reasons for a decision. The current town plan addresses a broad range of issues facing the town, including: community character, conservation, natural resources, open space, housing, economic development, community facilities, and transportation. The document lists a multitude of planning goals for the town.