4.6 Geography Markup Language (GML) (ISO 19136)
181
Styling
The GML requires a strict separation of data and presentation. Therefore none of
the GML data description constructs such as features and geometries have built-in
capabilities to describe the styling information. In order to simplify the handling of
GML adefault styling mechanism was created as a separate model that can be
"plugged-in" to a GML data set. The default style schema depends on the W3C Synchronized Multimedia Integration Language (SMIL) (SMIL 2001).
The GML styling mechanism distinguishes between four kinds of styling types.
The feature style applies to each feature independently. The geometry style describes
the style for one geometry of a feature. The topology style describes the style for one
topology property. The label style describes the style for the text that is to be displayed along with the graphical representation.
The presentation consists of styling elements. The symbol element specifies a
graphical symbol. It may be defined within the GML application schema. This case
is called "inline". It also may be addressed by apointer to other GML- or non-GMLsources. This case is called "remote".
The style element is the term for simple symbols.
ISO 19136 (Geography Markup Language)
ISO 19123
(Schema for coverage
geometry and functions)
Abstract Coverage
I
I
I
H Discrete C. I
I Multi Point C.
I
Discrete Point Coverage
I
I
H Multi Surface C. I I
Discrete Surface Coverage
I
H GriddedC. I I
Discrete Grid Point Coverage
Y Rectified Gridded C.
I
referenced Discrete Grid Point
Coverage
l Continuous C.
Fig. 4.82. Comparison between the coverage types in ISO 19136 and ISO 19123