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MassGIS Data: Licensed Google Ortho Imagery

August 2018
Google Imagery available as a web service for all Massachusetts state government agencies, and to the public in OLIVER and other MassGIS web maps.

View imagery and index

This is a licensed product with limited availability to non-government users.

New! (8/3/18) -- Spring 2018 imagery for Greater Boston/MetroWest areas
New! (6/26/18) -- Late winter 2018 imagery for the Cape Cod and the Islands

See the index map below for the dates of the most current Google Imagery

Google Imagery shown at Zoom Level 20 (scale 1:564)

MassGIS has purchased a subscription for direct access to the latest high-quality Google ortho imagery. It provides all state government agencies and political subdivisions of the commonwealth with Google's most current 6-inch resolution, natural color aerial imagery for all of Massachusetts.

The current Google imagery was acquired during 2014, 2015, 2016, 2017 and 2018 flights. Previous flights dating back to 2013 are also available.

Many users are familiar with the "Satellite" or "Earth" view in Google Maps. Though much of that image basemap seen online is from the same flights, the product licensed by MassGIS has a higher level of positional accuracy because it has been reprocessed using existing ground control points where available (mostly in high density urban areas). The imagery has a horizontal positional accuracy of 1 meter or better circular error with 90% confidence interval as described in the National Standard for Spatial Accuracy (NSSDA). It also can be used in applications other than Google Maps and Earth.

The imagery is served from Google's Cloud Mapping Platform via an OGC compliant Web Map Service (WMS) and Web Map Tile Service (WMTS). These services may be added to desktop GIS, CAD and other software and web applications that support WMS and WMTS. The spatial reference of the map services is Web Mercator EPSG:3857. The tiles are cached at 21 scale levels (0-20). DPI is 90.714.

The license agreement with Google, through a partnership with geospatial consulting firm AppGeo, allows MassGIS to receive frequent updates and take advantage of Google's investment in deploying a national imagery collection program. This license model has advantages and disadvantages. The advantages are that it provides significant cost savings for the commonwealth compared to past custom projects of purchasing imagery on our own. MassGIS also avoids costs for data storage and staff time spent producing and serving tile caches. The disadvantages are that the imagery is usually, although not necessarily always, acquired when leaves are on the trees. Thus in developed areas with mature trees, valuable details are often obscured and image interpretation using software does not yield useful results. 

Index of the most current imagery by year: Google Imagery Index Map - Dates of Photos

The index is based on the COQGOOGLEIMGIX_POLY feature class. This was created from GeoJSON files from Google. MassGIS made minor edits to align flight area boundaries with imagery seams. Fields include:

Field Description
ACQ_DATE Acquisition date of the most current imagery
FLIGHT_NAME Name of the flight area
FLIGHT_STA State abbreviation associated with flight name
Download the Index (zipped shapefile)

Project FAQ

Who can use the Google Imagery Services?

The Massachusetts Google Imagery Service is a restricted license and is only for use by public organizations in the Commonwealth of Massachusetts (state, regional and local governments). Contractors for any public organization are permitted to use the imagery as long as the project or program being performed directly supports the public organization. Rights to use the imagery terminate upon completion of work by the outside entities.

The imagery is available for viewing by the general public without any restrictions in Oliver and in ArcGIS Online maps shared from a public agency's organizational account. The general public may not download the imagery or receive direct access to the web services.

For those who are not qualified to use the imagery, the USDA has a 2016 NAIP imagery service.

How do I get access to the imagery?

MassGIS can provide a custom URL link to any public organization in the commonwealth. A unique link for every organization is generated that may be shared within the organization but not outside of it. This will allow for tracking usage metrics and performance of the imagery service. Do not distribute the link outside of your organization or division. If the link is accidentally given out, contact MassGIS to have it revoked and reissued.

For Google imagery use in an ArcGIS Online or public facing applications, a second unique link locked to the application domain will need to be used. After receiving your first link by filling out the Request Form (see next FAQ item), email massgismail@state.ma.us to request a second link. Include the domain of the web app where it will be used, such as: eoeea.maps.arcgis.com or myorganization.org.

How do I request a link for my organization?

If you are working for a public organization in the commonwealth and would like to obtain a link for your agency, please read and fill out the Request Form.

How do I add the WMS or WMTS service to ArcGIS products?

Note for ArcGIS Online administrators: In order for your organizational users to access the services, go to My Organization > Edit Settings > Security tab and add these to the Trusted Servers list: orthos.massgis.state.ma.us and orthos-wms.massgis.state.ma.us. Then click “Save”.

MassGIS recommends using the WMTS service as it is optimized for efficient web delivery and map printing. Some software programs do not yet support WMTS but do support the older WMS protocol.

How do I add the services to other software?

"How To" documentation is available here: Bentley Microstation | AutoCAD Civil 3D 2016 | AutoCAD Map 3D | GlobalMapper

Do I need to reproject the imagery for use in my GIS software?

Because the Google image services are referenced to a Geographic Coordinate System with a WGS 1984 datum, if you use the imagery with MassGIS data in the NAD83 Mass. State Plane coordinate system it will be critical for end users that require the highest locational precision to set up their working environment through the use of the appropriate geographic transformation (Esri ArcMap users should use WGS_1984_(ITRF00)_To_NAD_1983). The correct geographic transformation parameter is needed to overcome the locational difference between the “realization points” of the WGS84 and NAD83 datums, which are about a meter apart. Without the proper geographic transformation, re-projection algorithms will not be able to resolve the last meter of positional accuracy. For many web applications and coarser resolution mapping needs, the transformation may not be of importance. See an example of setting a transformation in ArcMap Link to the image file..

What about image updates?

The most current imagery will always appear in the web service layer named "imagery". When new imagery is incorporated into the service for various areas of the state, the older imagery for those blocks will be placed into archived layers and will continue to be available.

For example, when you navigate to the WMTS service in ArcGIS, you will see the older imagery indicated with a year:

Google Imagery WMTS Layers

If you add a layer with a year in its name it will display only the imagery captured in that year. Adding the "imagery-2014" layer, for example, would display the following:

Goolge Imagery WMTS 2014 areas

Can I download or get a physical copy of the original image that is in the service?

Yes, although the web services must be used whenever possible. MassGIS will make exceptions to this for hardship situations, but usually only for situations where the application does not have web access, in which case JPEG 2000 files are available for individual agency use within the agency only. To learn more about requests for on premise imagery files, please read and fill out the Request Form.

How should I attribute the imagery if I used it on a printed map?

Include the text "Imagery (C) Google" or place one of these images on the map (right-click each to save locally):

Google Imagery C white on black   Google Imagery C black text

 


Last Updated 8/14/2018

Items

Contributor
Modified Date
2018-08-14
Release Date
2018-08-14
Frequency
Irregularly
Identifier
00491a7c-1d7e-4bc5-ba3c-39a0f8a29542
Spatial / Geographical Coverage Location
Massachusetts
License
Other (Non-Commercial)
Author
MassGIS
Contact Name
MassGIS
Contact Email
Public Access Level
Restricted
Data Quality
False
Content Type
Rights
Licensed only to state and local governments or companies under contract to those entities.
Language
English (United States)