Boston, Massachusetts Region 1:5,000 Color Ortho Imagery (1/2-meter Resolution), 2001

1/2-meter resolution 1:5,000 orthophoto image of the Boston region from April 2001. This datalayer is a subset (covering only the Boston region) of the Massachusetts statewide orthophoto image series available from MassGIS. It consists of 23 orthophoto quads mosaicked together (MassGIS orthophoto quad ID: 229890, 229894, 229898, 229902, 233886, 233890, 233894, 233898, 233902, 233906, 233910, 237890, 237894, 237898, 237902, 237906, 237910, 241890, 241894, 241898, 241902, 245898, 245902). These medium resolution true color images are considered the new "basemap" for the Commonwealth by MassGIS and the Executive Office of Environmental Affairs (EOEA). MassGIS/EOEA and the Massachusetts Highway Department jointly funded the project. The photography for the mainland was captured in April 2001 when deciduous trees were mostly bare and the ground was generally free of snow. The geographic extent of this dataset is the same as that of the MassGIS dataset: Boston, Massachusetts Region LIDAR First Return Elevation Data, 2002 [see cross references].

Planning and analysis, general mapping and display.

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Unknown None Horizontal control (referenced to NAD83) conforms to the Federal Geodetic Control Committee specifications for Second Order Class 2 GPS surveys. The images meet or exceed the National Map Accuracy Standards to the extent that 90% of the well defined features fall within 0.5mm of their true position on the ground at the nominal output scale of 1:5,000 (2.5m on the ground). Additionally, the maximum displacement of well defined features is less than 5 meters. BSC Group fulfilled land survey requirements by performing highly precise ground control survey & independent verification and validation of spatial accuracy. Vertical control (referenced to NAVD88) is within 10 cm. It is tied to second order Class II NGRS benchmarks. In addition the latitude, longitude and ellipsoidal heights of continuously operating GPS reference stations were incorporated into the control adjustment. Orthometric heights were directly measured or estimated from GPS derived ellipsoidal heights.

Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 2; ESRI ArcCatalog 9.2.2.1350.

Not applicable.