JPEG 2000 (GeoJP2/GMLJP2) Reader Parameters

Dataset Parameters

This parameter allows you to choose different naming schemes, and the number of feature types generated for the reader.

Feature type name choices:

  • From File Name(s) – Generates one feature type per source filename.
  • From Format Name – Produces only a single feature type containing the format name.

Schema Attributes

Additional Attributes to Expose

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.
 

Use Search Envelope

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.

Clip to Search 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 left unchecked (set to No), features that overlap the boundary will be included in their full (unclipped) form.
  • 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.

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).

Advanced

This parameter applies only when the georeferencing of the JPEG2000 dataset is stored via an embedded GeoTIFF.

  • When the parameter is set to Yes and the ProjLinearUnitsInterpCorrectGeoKey flag is present in the file, the coordinate system offsets will be assumed to be in the linear units of the projection.
  • When the parameter is set to No or the ProjLinearUnitsInterpCorrectGeoKey flag is not present, the Offsets in Coordinate System Units parameter is used to determine the interpretation of the coordinate system offsets.

This parameter applies only when the georeferencing of the JPEG2000 dataset is stored via an embedded GeoTIFF.

  • Yes – The coordinate system offsets stored in the GeoTIFF file will be interpreted as being in the linear units of the projection; this is correct according to the GeoTIFF specification.
  • No – The coordinate system offsets will be interpreted as being in meters; this is what is actually done in practice by many software packages.

Note that if the offsets are explicitly marked as being in the coordinate system units (via the ProjLinearUnitsInterpCorrectGeoKey flag), and the Prefer File Coordinate System Units parameter is set to Yes, this option is ignored.

This parameter specifies which georeferencing source(s) FME will look for. The browse button opens a Georeferencing Source Preference dialog, where you can select and order the following sources:

  • TAB File – This option will always be the highest priority, regardless of ordering.
  • World File
  • GeoJP2
  • GMLJP2

If you do not select any sources, no georeferencing data will be used.

Specifies whether to scale values for color bands that are a non-standard bit depth (that is, not 8 or 16).

  • Scale to Standard Bit Depth – Values will be scaled to a standard bit depth (that is, 1-7 bit bands will be scaled to 8 bits, and 9-15 bit bands will be scaled to 16 bits).
  • Do Not Scale – Values will be left unchanged. Note: This may result in images appearing very dark when viewed in the Data Inspector.

This parameter specifies how FME should calculate the JPEG2000 compression cache size.

  • Auto (default) – FME will calculate a cache size that is appropriate for the size of the raster data. This is the preferred option.
  • Manual – FME will use the value of the Compression Cache Size (MB) parameter. Use this option if a cache error occurs. The error will contain information about the prescribed manual cache size.

This parameter specifies the size of the JPEG2000 compression cache in megabytes (MB).

This parameter is only enabled when the Cache Size Calculation parameter is set to Manual.