January 2014

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Overview

These data layers are used to index the USGS 2013 Color Ortho Imagery tiles and MrSID mosaics.

The layer named COQ2013INDEX_POLY is an index for the original GeoTiff images and the MassGIS-produced JPEG 2000 versions. It stores the Web links for the JPEG 2000 free downloads. Each tile measures 1,500m x 1,500m. Click on the image at right to view a larger index map and also see the PDF version of the Index Map pdf format of orthos2013_index .

The layer named COQ2013MOSAICS30CM_POLY is used to index the MrSID mosaic images created from the original GeoTiffs at 30:1 compression ratio. Click on the image at right to view a larger index map and also see the PDF Index Map pdf format of 2013 USGS Color Ortho MrSID Mosaics Index Map for details.

Production

The GeoTiff/JPEG 2000 index polygons were delivered to MassGIS with the imagery from USGS, one for each of the three delivery areas (Boston, Worcester and Springfield). The Boston and Worcester polygons were referenced to the UTM Zone 19N coordinate system. The Springfield polygons were referenced to the UTM Zone 18N coordinate system. MassGIS projected each layer to the NAD1983 Mass. State Plane Mainland Meters coordinate system and merged them into this one feature class. Note that MassGIS did not project the imagery: the imagery for the Boston-Worcester area remains in UTM Zone 19N, and the Springfield area images remain in UTM Zone 18N, as delivered by USGS.

To create the MrSID mosaic index, MassGIS added the MOSAIC field to the original tile index and dissolved the layer on that field using ArcGIS 10.2. The MOSAIC field is the only field in the layer's attribute table.The MrSID mosaic index is referenced to the NAD1983 Mass. State Plane Mainland Meters coordinate system.

Image Index Maps

View/download detailed PDF maps of the 1,500m x 1,500m tiles index layer:

Attributes

The polygon attribute tables contains the following fields:

AttributeDescription
TILENAME    Unique 11-character ID for each 1,500m x 1,500m tile
DEL_AREA  Name of USGS project delivery area. BOS=Boston, SPR=Springfield, WORC=Worcester
URLWeb link for downloading JPEG 2000 tiles
MOSAICName (number) of the MrSID mosaic of which the tile's image is a part.

Maintenance

These datalayers are maintained by MassGIS.

Last Updated 1/7/2014