Downloads
Overview
These data layers are used to index the 2008/2009 Aerial Imagery tiles. They are stored in ArcSDE as follows:
- COQ2008INDEX_POLY - 2008/2009 Aerial Imagery Index (for MrSID 1,500m x 1,500m tiles)
- COQ2008MOSAICS30CM_POLY - 2008/2009 Aerial Imagery MrSID 30cm Mosaics Index
The 2008 15CM Mosaics are no longer available for download. Please see the data download page to download individual tiles
*IMAGE
See the PDF Index (file size 1MB) for more detail and as a reference when downloading the imagery.
Production
The 1,500m x 1,500m tiles index polygons were created by using the Generate Fishnet command in ArcGIS 9.2 and converting the line layer to a polygon feature class. The origin of the fishnet was chosen such that the maximum amount of 2008 imagery was covered after projection from the UTM Zone 19N coordinate system to NAD83 Mass. State Plane Mainland Meters. Each polygon is 1,500m by 1,500 meters, insuring that the original 15cm and 30cm resolutions would be preserved in the projected imagery and be fully contained in each tile. The TILENAME attribute was populated by creating centroid points for each polygon, adding its XY state plane coordinate to the point (with the Add XY tool). A new attribute was added to the point layer comprising the first 4 digits of each X and Y coordinate. A spatial join transferred the 8-digit string to TILENAME in the polygon layer. Each polygon was then coded for resolution and which mosaic would include it, for each resolution. The Dissolve tool was used to create the MrSID indexes, using the MOSAIC30CM attributes.
Attributes
The polygon attribute tables contains the following fields:
| Attribute | Description | Contained in Feature Class(es) |
| TILENAME | Unique 8-digit ID for each 1,500m x 1,500m tile | COQ2008INDEX_POLY |
| RESOLUT | Available resolution for the 1,500m x 1,500m tile: - 15cm and 30cm - 30cm Only | COQ2008INDEX_POLY |
| MOSAIC30CM | Name of MrSID mosaic comprising 30cm tiles | COQ2008INDEX_POLY COQ2008MOSAICS30CM_POLY |
| COQ2008 | "Y" if flown in 2008, "N" if flown in 2009 | COQ2008INDEX_POLY |
| COQ2009 | "Y" if flown in 2009, "N" if flown in 2008 | COQ2008INDEX_POLY |
Maintenance
These datalayers are maintained by MassGIS.
| Date published: | June 1, 2010 |
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| Last updated: | June 1, 2010 |