Georeferencer

Use the Georeferencer tool to give spatial properties to a non-referenced map by establishing a relationship between page locations in the document (using MAP Page Locations) and world locations. There are three sources for world locations: 1. an online map service; 2. entering location coordinates manually; and 3. MAP World Locations from an open document. After connecting page and world locations, the tool calculates combined error using different projected coordinate systems. Choose a projected coordinate system based on best fit and create a new MAP View to contain the spatial information.

Requirements

•Must start with an ungeoreferenced layer (Non-MAP Layer) with defined MAP Page Locations.

•A source of world locations. Sources are an online map service, world location coordinates that are manually entered, and MAP World Locations from an open document.

•A minimum of four-page/world locations should be used. However, it is recommended to use more locations for better accuracy.

•Data being georeferenced cannot have a perspective or skew. Incorrect results may occur if they do.

•Using an online map service requires active Internet connection.

Using Georeferencer

In all situations, it is required to define MAP Page Locations on an ungeoreferenced layer before choosing real-world locations to connect them to. Use the MAP Locations tool to plot MAP Page Locations in known locations so that it is possible to connect them easily to world locations. There are three sources for adding world locations that connect to MAP Page Locations: 1. an online map service; 2. entering location coordinates manually; and 3. MAP World Locations from an open document.

Click the Georeferencer button on the MAPublisher Toolbar or go to Object > MAPublisher > Georeferencer.

Use online maps to add world locations

Add world locations from online map services such as MapQuest. In the Georeferencer dialog box, click the online map service button to choose world locations for matching MAP Page Locations (if multiple map services are available, click the drop-down arrow to choose). In the Add World Locations dialog box, choosing a MAP Page Location from the drop-down list automatically pans and centers it on the artboard. Use the Zoom in and Zoom out buttons to enlarge or decrease the artboard zoom level. To navigate the online map, pan, and zoom with the mouse (and mouse wheel) or use the navigation control slider. Optionally, enter street or city names into the Place search bar to find places quickly.

To plot a world location position on the online map, navigate to a location that matches the chosen MAP Page Location and click it. A placemark designates that a world location has been set. To adjust the world location position, click and drag the placemark to a new location and release the mouse button. Unassigned MAP Page Locations are denoted by (UNASSIGNED) in the drop-down list.

The reference locations list gets populated with the matching MAP Page Locations and world locations. The World Location column shows that MAP Page Locations are matched with an online map world location.

Use a georeferenced document to add MAP World Locations

The source for world locations is an open Adobe Illustrator document with MAP World Locations already plotted in it. It is essentially retrieving MAP World Locations from another georeferenced artboard and using them in the current ungeoreferenced artboard. In the Georeference dialog box, click the Open documents button. When a document is chosen in the drop-down list, the list populates with found MAP World Locations. Click the list to choose MAP World Locations.

The reference locations list gets populated with MAP World Locations. Importing MAP World Locations with the same name as a MAP Page Location will automatically match them and add to the solution. Choose the matching MAP Page Locations for each row. The World Location column shows that it is matched using an open document.

Manually add X and Y world locations

In the Georeference dialog box, click the Add button to add new reference locations to the list. The MAP Page Location column automatically populates with available locations. To add X and Y (or Longitude and Latitude) world location coordinates, double-click the X and Y column entries.

The World Location column shows that MAP Page Locations are matched by manually entered world locations.

Georeference and Save

When at least four reference locations are valid, it is ready for georeferencing. The check box in the Use in solution indicates whether or not the reference location should be included in the georeference calculation. A minimum of four reference locations is required for georeferencing.

Click Georeference & Save to begin the georeference process. MAPublisher calculates the georeferencing and produces a list of coordinate systems that best fit the data.

The listed coordinate systems each have a Rank, Combined Error, and Rotation Value.  The Rank value represents a number that indicates the most appropriate coordinate system for the data. A value of 1.00 means the coordinate system is the best fit based on error values, coordinate system envelope fit, rotation, and other calculated factors. Rank values should be low but an appropriate match could be greater than 1.00. The Combined Error is the total error calculated (between MAP Page Locations and world locations) of X and Y reference locations. Click the Details button to see individual Error X, Error Y, and Combined Error for each reference location used in the calculation. The Rotation value indicates the amount of rotation required to georeference the data and will vary depending on the coordinate system. The resulting MAP View will be assigned this rotation.

After a coordinate system is chosen for the georeference, the final step in the process is to create a new MAP View that will contain the referencing information. Optionally, select layers to move to the new MAP View. These layers can also be moved to the new MAP View after.

Georeference Workflow (brief)

1.Place at least four MAP Page Locations on an unreferenced document in locations that will be matched to known world locations (or MAP World Locations for an open document source).

2.Decide which georeferencing source to use to connect MAP Page and world locations (online map, open document, or manual entry). Choose world locations based on the position of MAP Page Locations. Specify the georeference coordinate system if it is known.

3.Ensure a minimum of four reference locations is used in the solution and click Georeference & Save.

4.In the list of results, view coordinate system details, fitness, combined error, and rotation value. Choose the most appropriate coordinate system for the map and assign it to a new MAP View.

Important Georeferencer Notes

•Georeferencing cannot be performed on an unprojected map (i.e. a map in a geodetic coordinate system).

•It is recommended to use as many points as possible to achieve the best geocoding results.

•Reference points should be spaced out as best as possible (e.g. one in each corner of the artboard).

•Zoom in to the maximum zoom level to get the most accurate location. This is true when plotting both MAP Page Location and matching world location using an online map service.

•See MAPublisher Preferences to specify an alternate online map service.

•It is recommended to provide meaningful names to MAP Locations for easier identification.