Provides an interface to define layer creation and styling options for use with the Google Maps Engine Tables writer. This transformer is intended for users who are already familiar with the concepts of vector tables, layers, and layer styling in Google Maps Engine, and are looking to automate their workflows. Users who are not familiar with these concepts should first try Google’s tutorial at https://www.google.ca/earth/outreach/tutorials/mapseng_layers.html before using this transformer.
This transformer creates format attributes that are only recognized by the Google Maps Engine writer. These format attributes comprise the definition of a layer, and the presence of one or more of these format attributes will trigger layer creation.
Note that the Google Maps Engine Tables writer will not create layers when writing to a vector table that already exists on Google Maps Engine. When working with existing vector tables, all layer creation and styling options will be ignored.
Important Considerations
- Display Rule names are arbitrary, and do not need to be unique.
- The Filters section for each Display Rule defines filters that are passed along in the Display Rule definition that is supplied to Google Maps Engine. These filters are not evaluated by FME. GME Table Property Name in the Filters section must match a user attribute on the Google Maps Engine writer feature type. As filter definitions are not evaluated by FME, it is only possible to define filters based on attributes (properties) that will be present on the schema of the created vector table.
- The order of Display Rules is significant. For each feature, Google Maps Engine goes down the list of Display Rules. If the feature matches all the filters defined in the Display Rule, then that Display Rule is used to style the feature. No further Display Rules are evaluated, and only one Display Rule can be applied per feature. If the matched Display Rule doesn’t contain styling options appropriate for the geometry of the feature, the feature may appear invisible on the layer.
Parameters
Layer Info
Name
This optional parameter specifies the name to give the Google Maps Engine layer. It sets the gme_layer_name format attribute. If gme_layer_name is not provided, but other layer creation format attributes recognized by the Google Maps Engine writer are present, the layer will adopt the same name as the table (feature type).
Description
This optional parameter specifies a description to give the Google Maps Engine layer. It sets the gme_layer_description format attribute. If gme_layer_description is not provided, but a description was specified for the corresponding table via the Google Maps Engine writer’s feature type parameters, the layer will adopt the same description as the table.
Tags
This optional parameter specifies the tags to give the Google Maps Engine layer. Tags can assist with categorizing and searching through layers on the Google Maps Engine web interface. To edit this parameter, click the browse button to the right of the text field.
Tags may not contain commas. GoogleMapsEngineStyler will replace commas with underscores.
This parameter sets the gme_layer_tags format attribute. If gme_layer_tags is not provided, but tags were specified for the corresponding table via the Google Maps Engine writer’s feature type parameters, the layer will adopt the same tags as the table.
Display Rules
This table defines the Display Rules used to style features in the layer. Each row represents a single Display Rule.
Each Display Rule can contain styling options for points, lines, and polygons, as well as filtering criteria to specify which zoom levels and features for which the rule is valid. The order of Display Rules is significant: for each feature, Google Maps Engine goes down the list of Display Rules and selects the first rule for which the feature matched all filtering criteria. If the matched Display Rule does not specify styling for the feature’s geometry type, the feature will not be visible in the layer.
This table sets the gme_layer_style format attribute. The value will be JSON, even if the table is empty. If no rules are specified, the Google Maps Engine Tables writer will create a layer that adopts the default styling rules from Google.
Rule Name
This field specifies the name of the Display Rule. Display Rule names are arbitrary, and do not need to be unique. The name appears when editing layer styles from the Google Maps Engine web interface, and can be used to describe the purpose of each Display Rule.
Style and Filters
Click the button to open the filtering and styling options dialog.
The Filter section allows you to specify the zoom level range and conditions under which the Display Rule is valid. The Display Rule will only be applied if all the conditions defined in this section are met.
Zoom levels range from 0 to 24, inclusive, where 0 is the most zoomed out, and 24 is the most zoomed in. The Minimum Zoom and Maximum Zoom parameters make it possible to apply different feature styles depending on the zoom level.
Although the table of filter conditions appears similar to the Tester transformer, it does not function the same way: filter conditions are not evaluated by FME. Instead, filter conditions are passed to Google Maps Engine, and are evaluated server-side.
When specifying filter conditions, ensure that the GME Table Property Name corresponds to an attribute on the Google Maps Engine writer feature type. The operator and value of the filter condition must also be appropriate for the corresponding attribute type. The Google Maps Engine writer will perform some basic validation of these fields prior to creating a layer.
The styling sections for point, line, and polygon are optional. These sections contain parameters for the visual representation of features that match the filters specified in the previous section. If a feature matches a Display Rule, but the Display Rule does not contain any styling information for its geometry, the feature will not be visible on layers and maps. For information regarding the various styling options available, refer to the API documentation at http://developers.google.com/maps-engine/documentation/reference/v1/layers/create
Note: Points can be styled using either one of the existing icons from Google, selectable from the included gallery, or by specifying the asset ID of a custom icon defined through the Google Maps Engine web interface.
Additional References
For more information about the Google Maps Engine Tables writer, see the Google Maps Engine Tables writer chapter in the FME Readers and Writers manual. In Workbench, select Help > FME Readers and Writers Reference.
For more information about the options available, refer to the API documentation at http://developers.google.com/maps-engine/documentation/reference/v1/layers/create.
Editing Transformer Parameters
Using a set of menu options, transformer parameters can be assigned by referencing other elements in the workspace. More advanced functions, such as an advanced editor and an arithmetic editor, are also available in some transformers. To access a menu of these options, click 
beside the applicable parameter. For more information, see Transformer Parameter Menu Options.
Transformer Categories
FME Licensing Level
FME Professional edition and above
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Tags Keywords: "Google Maps"