Feature Types

The elevation features may be named differently within some elements, however they have the same behaviours and are recognisable by their icon and order. The feature surface has all four types of data, which makes it suitable as a base example. Any combination of the following terrain features (where available) can be used to define the terrain:

	Outlines This element is used to define the outline(s) of the feature surface. There will almost always be only one outline, but it is possible to define more than one to create several 'islands' of terrain. It is also possible to create holes in the terrain by adding internal outlines. There are also different types of Outline: i) Extrapolate from other Features (Default): Takes the levels from contained elevation features that you have defined (e.g. contour lines and points). ii) Define Varying Levels: Allows you to set levels for the outline which vary at each point. This can be used if you need maximum control of the surface outline elevations. iii) Define Fixed Level: Allows you to set a single level for the outline, this is only used in very unique scenarios. iv) Use Ground Levels: Snaps the Outline elevations to the ground. (This can only be used with a feature surface used to define proposed earthworks)
	Contour Lines Contour lines (or isolines) are used to define lines on the terrain with a fixed elevation
	Break Lines Break lines are used to defined lines on the terrain which have a varying elevation
	Point Levels Point levels are used to define the levels for individual points in the terrain area

Outlines

This element is used to define the outline(s) of the feature surface. There will almost always be only one outline, but it is possible to define more than one to create several 'islands' of terrain. It is also possible to create holes in the terrain by adding internal outlines.

There are also different types of Outline:

i) Extrapolate from other Features (Default): Takes the levels from contained elevation features that you have defined (e.g. contour lines and points).
ii) Define Varying Levels: Allows you to set levels for the outline which vary at each point. This can be used if you need maximum control of the surface outline elevations.
iii) Define Fixed Level: Allows you to set a single level for the outline, this is only used in very unique scenarios.
iv) Use Ground Levels: Snaps the Outline elevations to the ground. (This can only be used with a feature surface used to define proposed earthworks)

Contour Lines

Contour lines (or isolines) are used to define lines on the terrain with a fixed elevation

Break Lines

Break lines are used to defined lines on the terrain which have a varying elevation

Point Levels

Point levels are used to define the levels for individual points in the terrain area

The properties of each feature vary depending on the feature type, but they all have a 'Tag' which can optionally be set. This is an identifier for the feature (akin to the feature's name), and it is used to help the user identify particular features.

This form includes three display buttons as described below:

① Zoom to Extents This button zooms to designer to extents (i.e. frames all elements in the designer panel)
② Zoom to Selection This button zooms to designer to selected features
③ Toggle Grid This button toggles the grid in the designer on and off.
④ Toggle Site Plan This button toggles the site plan in the designer on and off.

The rest of the controls on this form are used to add, remove and edit the terrain features. They are described in detail in the following sections.

Learn how to define boundary outlines in the video Understanding Feature Surface Outlines