USGS Topographic Quadrangle Images - December 1995, June 2001
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Overview
MassGIS scanned the USGS topographic quadrangles to create a digital database that can provide images of the paper maps. These images can be used as a backdrop for plotting vector data and for interpretation and analysis. MassGIS scanned the 15-minute series (vintage 1982-1990) where these maps were available; the 7.5-minute maps (1967-1979) were used elsewhere. See the Index Map for details. Most paper maps are at 1:25,000 scale; some older 7.5-minute quads were produced at 1:24,000 scale. The data are available in two forms:Production
- individual 4km x 4km images, tiled by the Digital Orthophoto Quad (DOQ) Index, producing almost 1,600 images for the 189 paper quads (Dec. 1995). Available on CD-ROM or via Free Download.
- one single statewide image - a digital seamless "mosaic" of all the quads in the state, stored in the MrSID image format (June 2001). Available on CD-ROM.
In ArcSDE the images are stored in a Raster Catalog named IMG_USGSQUAD. In addition, a mosaic is stored in ArcSDE as IMG_USGSQUADM.
View all the images in the state with the MassGIS Topographic Tour
Click on above image for more detail
The paper maps were converted to image format by scanning. Unfolded USGS quadrangles were used if available. For the dates of the maps that MassGIS used in this project, see the Index Map. The maps were scanned with a Tangent CCS500-50TF drum scanner into 8 bit compressed TIFF images.
The original 4km x 4km images (produced in 1995) were scanned at 250 dots per inch (dpi). Each scanned quad was registered to MA State Plane NAD27 in ARC/INFO with the REGISTER command. After registration, the images were converted to grids. In Arc's GRID module they were then clipped of map marginalia and merged with neighboring sheets. The resulting grid was projected into NAD83 MA State Plane meters. Afterwards, the grid was clipped by a DOQ template and each clipped grid was converted back into a TIFF image. The quad images are stored with the DOQ tiling scheme to facilitate storage of the images and allow for faster drawing times for local map extents. The image name is an index sheet-ID composed of the first three digits of the x and y NAD83 state plane coordinates of the image's lower right corner, prefixed by the letter 'q'. For example an image that covers part of Northfield, MA, with lower right corner coordinates of 125000m 983000m, is named q125983. The 4km-sq. images are available in both Tiff and MrSID formats and include .tfw and .sdw header files, respectively, for registration in GIS software. These images may be obtained on CD-ROM (see the data ordering section) or by free download.
The same paper maps were scanned for the seamless statewide mosaic image, but at 500 dpi (in late 2000-early 2001). Because of their large file size the scans were registered directly to the NAD83 MA State Plane meters coordinate system instead of to NAD27 and projected. The images were converted to grids and then clipped of marginalia, merged with neighboring sheets, cut into the DOQ Index-tiled 4km x 4km blocks, and resampled to 2-meter pixel resolution. The grids were converted to Tiff images and fed into Lizardtech's MrSID Geospatial Encoder 1.4 to produce the statewide mosaic. The MrSID software requires that all images included in a mosaic have the same pixel resolution. In order to achieve the best image quality, rescanning all the maps at 500 dpi and resampling to a consistent pixel size (2 meters) was chosen over resampling the original 1,600 250 dpi images, which have slightly varying resolutions (approximately 2.5 meters). The images from this second scan of the maps were used to create the ArcSDE mosaic layer IMG_USGSQUADM (in March 2008).
The statewide mosaic, named usgs.sid, totals 655 megabytes in file size and is accompanied by the usgs.sdw header file. It is available for distribution on CD-ROM (see the data ordering section).
Related Sites:
- Topographic Map Symbols (Legends)
- UNH Dimond Library's Historic USGS Maps of New England
- WWW.TOPOZONE.COM - The Web's Topographic Map
- Maptech MapServerMassGIS does not sell or distribute paper copies of USGS Topographic maps. Such maps may be viewed at some major libraries and are for sale by calling 1-800-USA-MAPS.
