OGC GeoPackage Tiles Reader Parameters

About Database Connections

Database formats include a Database Connection parameter that defines and stores authentication information. For general information about sharing database connections, please see Using Database Connections. Using Database Connections.

Note that Database Connection parameters differ slightly, depending on context and/or database format.

Connection

From the Connection parameter in a database format, you can do one of the following:

    Select an existing, previously defined connection. See the section Reusing a Database Connection in Using Database Connections

    Select Add Database Connection to define a new connection. See database-specific parameters below, as well as the section Adding a Database Connection in a Workspace in Using Database Connections The new connection can be made visible only to the current user, or can be shared among multiple users.

Database Connection

If you have already selected the file-based database connection from the Add Reader or Add Writer dialog, you will be prompted for the file or folder from the Add Database Connection dialog, and this parameter group will not be visible.

Parameters

Specifies the zoom level that will be used when reading the GeoPackage Tiles tile data.

The default is the maximum possible resolution zoom level.

This parameter allows you to choose different naming schemes for a feature type, and the number of feature types generated for the reader. The Feature Type Name changes, depending on the selection.

Value

Feature Type Name

Example
From Format Name <reader_type_name> GEOPACKAGE_RASTER
From File Name <filename> file
From Subdataset Name <tiles_table_name> tiles

Advanced

Enforce Foreign Key Integrity

The GeoPackage standard requires that all foreign key values in a GeoPackage database are valid (see Requirement 7 of the specification).

Option

Description

Yes (default)

The reader will ensure that all foreign key values in the database are valid before reading any data. If any foreign keys are invalid then the translation will fail.

No

The reader will attempt to read the data without performing any foreign key checks.

Use this parameter to expose Format Attributes in FME Workbench when you create a workspace:

  • In a dynamic scenario, it means these attributes can be passed to the output dataset at runtime.
  • In a non-dynamic scenario, this parameter allows you to expose additional attributes on multiple feature types. Click the browse button to view the available format attributes (which are different for each format) for the reader.

A search envelope (also known as a bounding box) is a rectangular area that defines a geographic area. In FME, the easiest way to define a search envelope is to use search envelope parameters.

Defining a search envelope is the most efficient method of selecting an area of interest because FME will read only the data that is necessary – it does not have to read an entire dataset. Search Envelope parameters apply to both vector and raster datasets and can be particularly efficient if the source format has a spatial index.

Most FME readers have parameters to define the search envelope of data that is being read:

Screenshot with blank search envelope min and max x and y parameters

The parameters include the x and y coordinates of the bounding box as well as a parameter that defines the coordinate system.

How to Define the Bounding Box

Using the minimum and maximum x and y parameters, define a bounding box that will be used to filter the input features. Only features that intersect with the bounding box are returned. Note that the bounding box intersection is not a full geometry intersection (based on spatial relationships) that would be returned by a transformer like the SpatialFilter.

Note  If all four coordinates of the search envelope are left at 0, the search envelope will be disabled even if this option is checked.

Search Envelope Coordinate System

Specifies the coordinate system of the search envelope if it is different than the coordinate system of the data. The coordinate system associated with the data to be read must always be set if this parameter is set.

If this parameter is set, the minimum and maximum points of the search envelope are reprojected from the Search Envelope Coordinate System to the reader’s coordinate system prior to applying the envelope.

The underlying function for Use Search Envelope is an intersection; however, when Clip to Search Envelope is checked, a clipping operation is also performed.

  • When checked (set to Yes), this option instructs FME to clip features to the exact envelope boundary. FME removes any portions of imported features being read that are outside the search envelope.
  • When left unchecked (set to No), features that overlap the boundary will be included in their full (unclipped) form.

Clip to Search Envelope: No

Clip to Search Envelope: Yes

Any features that cross the search envelope boundary will be read, including the portion that lies outside of the boundary.

Any features that cross the search envelope boundary will be clipped at the boundary, and only the portion that lies inside the boundary will be read.

The search envelope includes the bounding box and the extent of the raster.

The search envelope includes only the area within the bounding box.

The raster size will still match the bounding box, but the area without data will be filled with Nodata values to represent the absence of data, if the source raster has them.

Raster Nodata may be a single value across all bands, a single value per band, or a separate alpha or transparency band that indicates the lack of data values (this is more common in images than other types of rasters).