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Description: <DIV STYLE="text-align:Left;"><DIV><DIV><P><SPAN>This dataset consists of 2-dimensional roof outlines ("roofprints") for all buildings larger than 150 square feet, as initially interpreted by a contractor (Rolta) for the whole area of the Commonwealth using DigitalGlobe ortho images obtained in 2011 and 2012, supplemented with LiDAR (Light Detection And Ranging) data collected from 2002 to 2011 for the eastern half of the state.</SPAN></P><P><SPAN>The roofprints as delivered by Rolta were enhanced by MassGIS using Normalized Digital Surface Models (NDSMs) derived from the same LiDAR data. Other layers were used, including the Standardized Parcels, to aid in review, especially where LiDAR data were not available.</SPAN></P><P><SPAN>In 2019, MassGIS refreshed the data to a baseline of 2016 and continues to update features using newer aerial imagery that allows MassGIS staff to remove, modify and add structures to keep up with more current ground conditions. Structures from the original compilation that are removed are stored in an "archive" feature class for edit tracking and historical purposes. Also in 2019, MassGIS replaced the polygons in Boston with data from the city. In March 2021, the layer was updated with 2017 and 2018 structure review edits along with the first data edits compiled atop spring 2019 imagery. Updates based on 2019 imagery were completed in July 2021. Updates based on 2019 imagery were completed in August 2022. Updates based on 2021 imagery were completed in October 2023.</SPAN></P><P><SPAN STYLE="font-weight:bold;">Last updated on 11/1/2023.</SPAN></P><P><SPAN>In ArcSDE the layer is named STRUCTURES_POLY. It is updated periodically from STRUCTURES_POLY_V, which is registered as versioned for editing.</SPAN></P></DIV></DIV></DIV>
Description: <DIV STYLE="text-align:Left;"><DIV><DIV><P><SPAN>Assessor parcel data for Town of Walpole. Developed from existing digital data. Geometry and attribute data updated through December 2024.</SPAN></P></DIV></DIV></DIV>
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Description: <DIV STYLE="text-align:Left;"><DIV><DIV><P><SPAN>The political boundary datalayer is a polygon representation of town boundaries created from arcs developed from survey coordinates extracted from the 68-volume Harbor and Lands Commission Town Boundary Atlas for the 351 communities (cities and towns) in Massachusetts. The Atlas was published in the early 1900's and is maintained by the Survey Section of Massachusetts Highway Department. For communities with a coastal boundary, MassGIS has collaborated with Massachusetts Water Resources Authority and the Department of Environmental Protection to complete a 1:12000 scale coastline. The boundary for the coastline was defined as being the upland side of tidal flats and rocky inter-tidal zones. Note that the 351 communities are the official municipal names, not including "villages" or other sections of towns. The TOWNSSURVEY_POLYM layer was created by dissolving the TOWNSSURVEY_POLY feature class; a subset of the attribute table was retained, and the AREA and SQUARE_MILES fields were calculated for the entirety of each town.</SPAN></P></DIV></DIV></DIV>