![]() ![]() Many of these datalayers were compiled at "Quad" or larger scale and are suitable for spatial analysis using the MassGIS base map data. Responsibility for maintaining and updating these datalayers remains with the agencies that produced them, as indicated in the individual descriptions. ![]() These datalayers include those developed by the agencies for the purpose of enforcing environmental regulations or in support of various types of environmental analysis. In addition to base map data, MassGIS distributes datalayers developed by EOEEA and its agencies, as well as data from Federal agencies. The imagery is available in Tiff and MrSID, JPG2000 and ERDAS Imagine formats. In addition to vector (point/line/area) data, MassGIS also distributes raster (image) data (ortho images, scanned USGS quads, impervious surface, and others). The individual description pages state the layer's scale. Other datasets have been developed at smaller scales (1:100,000 or 1:250,000). This 1:5,000 scale base map is now considered the new state basemap for data. Large scale data have been developed from the digital orthophotos. MassGIS is making increasing amounts of large scale data available which is suitable for spatial analysis within towns or of individual parcels of land. ![]() So-called "Quad" scale datalayers were typically compiled from 1:25,000 scale maps (the scale used on the popular USGS 7.5 minute topographic map quadrangles) and are suitable for spatial analysis of larger areas such as counties or of entire towns. Several of the MassGIS base map features are available in two scales. More recently developed data were developed by other state agencies and derived from the digital orthophotos providing improved basemap accuracy. Geological Survey data and represent many of the feature types found on USGS topographic maps. Many of the base map datalayers maintained by MassGIS have been derived from U.S. These datalayers include features such as roads, streams, schools and political boundaries-relatively permanent, widely used features. ![]() In its role as a repository for GIS data, MassGIS is responsible for maintaining the "base map" datalayers which commonly appear on many kinds of maps. ![]()
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