Discover Server

AGRC’s cloud-based server Discover provides imagery and base maps services in Open Geospatial Consortium (OGC) standard Web Map Tile Service (WMTS) and Web Map Service (WMS) in the Web Mercator WGS84 projection (wkid: 3857).

One featured offering from Discover is statewide 6 inch imagery collected and licensed by Google. Due to this licensed content, access to the Google imagery is only for Utah’s cities, counties, special districts, state agencies, K12/Higher education, and tribes and contractors and formal partners of the immediate licensees. To obtain access to the Discover server you need to fill out and understand the Organizational Usage Agreement available from the Google Imagery License page. Once the Organizational Usage Agreement is completed, you will receive information about the services and URL links to access the Discover server. The URLs to access the server will contain a quad-word (ex. https://discover.agrc.utah.gov/login/path/your-unique-quad-word/) unique to each user or organization.

If you are not covered by the license agreement for the Google imagery service you will need to fill out the Discover Server Access form. Once the form has been completed, you will receive information about the services and URL links to access the Discover server. The URLs to access the server will contain a quad-word (ex. https://discover.agrc.utah.gov/login/path/your-unique-quad-word/) unique to each user or organization.

Coordinate System and Datum

The native coordinate system for the Google files and services is Web Mercator with a WGS 1984 datum. Many end users in Utah work in coordinate systems with a different datum (NAD 1983 for example). 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 software users should use NAD_1983_To_WGS_1984_5). The geographic transformation parameter is needed to overcome the locational difference between the WGS84 and NAD83 datum’s “realization points” that are about a meter apart. Without the proper geographic transformation, reprojection algorithms will not be able to resolve the last meter of positional accuracy. In order for the imagery to be positioned as accurately as possible when there is a difference between the native projection and datums of the imagery and the client viewing application, a datum conversion must be set. For Pro/ArcMap users, the appropriate datum conversion for Utah is NAD_1983_To_WGS_1984_5. The default (no transformation specified) will likely introduce several feet of horizontal positional error. More information: NAD_1983_To_WGS_1984_5

Horizontal Positional Accuracy

Stated horizontal positional accuracy of the Google imagery is expected to achieve or exceed one meter (CE90) in most areas without significant vertical relief. Higher precision is expected in urban areas, where existing supplemental ground control was more abundant.

Adding a WMTS or WMS Service to ArcMap

Adding a WMTS service to ArcMap is very simple. Go to Add Data -> GIS Servers -> Add WMTS Server and paste the WMTS link you have been provided into the URL: line then hit OK. Now navigate to the newly added WMTS ‘utah imagery - WMTS on discover.agrc.utah.gov’ by going to Add Data -> GIS Servers. If you drill down through the service folders you will find the Utah or Google layer to add. The WMS service can be added by following the instructions above just substitute GIS Servers -> Add WMS Server. Take a look at this page for more inforamtion about the available layers and using the base maps and imagery services in Pro/ArcMap.

Adding a WMTS or WMS Service to a Web Map

Interested in using AGRC’s Web Mercator services in your web maps? Take a look at this page for more information. Remember, if the web map is going to be public facing you need to request a separate quad-work link. To do this send an email to Rick Kelson rkelson@utah.gov and provide your web map URL domains.

Adding a WMS Service to CAD

Printing Web Maps with Discover Services

Take a look at this blog post for information about Printing Web Maps with Discover Services.

Google Archive Services

In addition to the statewide Google imagery service layer there are archive layers available (ex. Google 2011archive) of the Google imagery organized by year collected.

Google Flight Dates

The dates of each Google imagery flight block can be downloaded from our ftp site as a shapefile, viewed in ArcGIS Online, or utilized through our SDE as layer SGID10.INDICES.Google_UtahServiceDates.

Pro/ArcMap User Considerations

If you have not yet received quad-word links to the service (ex. https://discover.agrc.utah.gov/login/path/your-unique-quad-word/) that do not require a username and password contact Rick Kelson.

Users experiencing problems with the service, such as blurry tiles or different year vintages at different scales, may need to clear their local cache.

  • ArcMap Go to the service’s Layer Properties -> Cache tab and selecting Clear Local Cache Now. Be patient as this could take several minutes. If the blurry tiles persist you have the options to Clear cache when the session ends or Don't cache and data locally. Another option is to completely clear your ArcMap cache by going to Customize -> ArcMap Options -> Display Cache -> Clear Cache.

  • ArcGIS Pro Go to the service’s Layer Properties -> Cache tab and selecting Clear Cache. You can also clear your entire Pro cache by going to the Pro project’s Options -> Display and check Clear cache and selecting OK.

ArcMap 10.1 users should use the WMS service and not the WMTS. The WMTS in ArcMap 10.1 does not render correctly.

Usage Tracking

To access the GCP services individual organizations will be provided URL links for the service unique to their organization. This will allow for tracking usage metrics and performance of the imagery service. Do not distribute the URL links outside of your organization or division.

Google Logos

Download zipfile of Google logos white transparent white on black

Requests for On-Premise Use

Request can be made to consume the imagery off-line when the provided imagery service does not suffice. Please provide the following information to Rick Kelson at rkelson@utah.gov for consideration:

  • Name & organization:
  • Reason for request:
  • Working on behalf of:
  • Project names:
  • Project locations:

Frequently Asked questions

  • From time to time it is suggested that you refresh the connection to the imagery services by right-clicking your service connection, in ArcCatalog or ArcMap’s Catalog Viewer, and select the Refresh button to see the latest list of available services.
  • Since the Google acquisition flight blocks are not done all at once (as opposed to the NAIP product for example), there will certainly be color and positional changes at flight block boundaries. For large area maps, the color-balanced NAIP may be a more aesthetically pleasing cartographic choice.
  • A tile index of the .jp2 images that make up the service is available from our SDE as SGID10.INDICES.Google_Tiles or as a download from our ftp.
  • For future updates, Utah can certainly pass along requests to Google for additional update areas or for specific collection periods. But there is no provision in the current contract to create any expectation that those requests will be acted upon.
  • AGRC has downloaded a statewide master set of the image files for redistribution, as the download process directly from Google incurs transactional costs for cloud server & bandwidth usage.
  • AGRC has a feedback reporting form for imagery users around the state to report imagery and service issues so these can be passed along to Google. Please direct your feed back to the form.