Feature Representation (VPF Writer)

The features in a VPF writer’s feature set can be classified as either metadata or feature class features.

Metadata features are used to supply values for entries in a VPF database’s metadata tables. There is a simple mapping from an FME metadata feature to VPF metadata table: each metadata feature represents one row in the VPF metadata table.

Feature class features are geometric entities that carry all the information necessary to populate the VPF tables related to a feature class. A typical feature class is composed of a feature table, a set of primitive tables, a primitive join table and a set of related attribute tables. When writing a geometric feature, the VPF writer breaks an incoming feature down into primitives, populates its primitive tables, feature table and related attribute tables, and then calculates the indices related to the these tables.

Attributes in VPF products are case-sensitive. All the output products that the writer supports use lowercase attributes and all FME feature attributes must also be lowercase.

The following table lists the format attributes that are used by the VPF writer to write geometric information. Valid attribute values for feature attributes can be found in a product specification. When a feature is written to a table, a default value is often used.

Attribute Name

Description

Defined On

vpf_type

A feature class feature has one of the following geometric types:

vpf_area

vpf_line

vpf_point

vpf_text

A metadata feature has the geometric type vpf_none.

All features

vpf_text_string

The character string to be used for a feature with type vpf_text.

vpf_text

vpf_text_height

The height of a vpf_text feature. See Note.

vpf_text

vpf_text_font

The font used to display vpf_text feature. See Note.

vpf_text

vpf_text_color

The color used to display vpf_text feature. See Note.

vpf_text

vpf_text_style

The style used to display vpf_text geometry. See Note.

vpf_text

vpf_rotation

The rotation at which the text is to be displayed. This is calculated from the lower left and lower right coordinates of the text line, and is expressed in degrees counterclockwise from due East. It defaults to 0.0 if the text geometry has only one coordinate in the VPF data.

vpf_text

vpf_text_scale

The scale read from the Library Header Table (LHT) in the library containing the feature. Used to calculate a new height from the fme_text_size if the vpf_text_height is not present. For all other purposes, this attribute is ignored by the writer.

vpf_text

vpf_original_geometry

Optional. The original geometry as read by the VPF Reader in the Well Known Text (WKT) format. It is only present if the original vpf text primitive had more than 1 coordinate. If the text feature has the same geometry as when it was read, then this attribute will provide the geometry to the writer.

vpf_text

Note: Note: Only VMap0, VMap1, VMap2 and UVMAP product types support the storage of this symbolic information in symbol.rat table. DNC does not support symbol.rat tables. Text features must have the same symbolic information for each unique symbol identifier symbol_id supplied on a feature. The writer will ignore the symbolic information from features with no symbol_id attribute.