Orthophotography

Update 03/30/2006

New orthoimagery, flown in the Spring of 2005-2005 has been received for parts of Central and Northern Maine. The delivery of the remaining orthoimagery is now expected to be completed by September 2006. Ortho delivery has been prioritized by blocks of USGS 7.5 minute quadrangles for 2 foot resolution (one quarter of a USGS quad) and 1 foot resolution (one sixteenth of a USGS quad). The attached graphic B is a simplified map of imagery already received and imagery scheduled for delivery. To see if a specific township will be covered by new orthoimagery please see attached graphic A. The Priority Areas were established based on perceived needs for projects being undertaken by state government or municipalities.

The major project to date by the Maine GeoLibrary Board is a $3.2M project to create, in cooperation with the U.S. Geological Survey (USGS), full color, high resolution digital orthophotos for most of the populated areas of Maine. A digital orthophoto, or orthoimage, is a digital image of an aerial photograph in which displacements caused by the camera and the terrain have been removed. It combines the image characteristics of a photograph with the geometric qualities of a map so that features are displayed in their true ground position. Orthophotos are often used as a backdrop in a Geographic Information System (GIS) and as the base for creation or update of vector mapping data. They also display features that may be omitted on a standard map.

The attached graphic map shows the original proposed orthophoto coverage and subsequent changes in the project. The orange shaded area labeled "Ortho_HF" is purchased, color orthoimagery covering all of Cumberland and part of Androscoggin counties. This was flown in the spring of 2001 and has a pixel resolution of ½ foot. The town of Fort Fairfield, labeled "Ortho_FF"donated color orthoimagery flown in the spring of 2003 with a pixel resolution of ½ foot.

The red shaded areas, labeled "Tier A", were flown at a photoscale of 1 inch = 1,000 feet in the spring of 2003, 2004 and 2005. They are being produced as natural color orthoimages with a pixel resolution of 1 foot. All of the Tier A orthoimages will be produced.

The yellow shaded areas, labeled "Tier B", were flown at a photoscale of 1 inch = 2,000 feet in the spring of 2003, 2004 and 2005. They are being produced as natural color orthoimages with a pixel resolution of 2 feet. Due to budget constraints, not all of the Tier B orthoimages are being produced in the current contract.

The green shaded areas, labeled "Tier C" were not flown as part of this project and no new orthoimages will be produced. These areas are covered by existing black and white orthoimages flown in 1996-1998 and at a pixel resolution of 1 meter.

In the area outlined in a heavy red line labeled "Completed Contract", all Tier A and Tier B orthoimages have been completed. The remaining Tier A and Tier B orthoimages will be produced in the areas outlined by a heavy green line labeled "Current Contract". The projected time frame for completion is May of 2006.

For additional information please contact Larry Harwood, Maine Office of GIS, 145 State House Station, Augusta , ME 04333 , telephone 207-624-8879, or E-mail at
larry.harwood@maine.gov .

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Orthophotography

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