Terminology

Some specific terms and conventions used by application. Bold words refer to other definitions within this page.

Alignment

Road or rail center line formed by two separate parts: horizontal and vertical. Horizontal alignment defines the road position in horizontal plane. It may contain straight segments, circular arcs and transition curves. Transition curves are typically clothoids, but other types are sometimes used in rail alignments. Vertical alignment defines the profile of the road. It contains straight sloping segments and circular vertical arcs.

Arc

Arc may by independent line object or it may be part of the longer line. Arc endpoints may have different elevations making it technically helix. It is always circular when looked from above and contains hidden center point between endpoints.

Area

Area is a closed boundary line marked as an area. May contain inner islands which are excluded from the outer main area.

Attribute

User editable data stored to an object. Contains name tag and value as string. Tag works usually directly when used alone, but must be prefixed with $ if part of the longer text. For example, attribute $DATE may contain object creation date.

Circle

Circle is an arc with same endpoints and hidden center point. It is always horizontal. Behaves also like a closed line.

Clothoid

Most common transition curve used in horizontal alignments. Usualy defined by start curvature radius, end curvature radius and constant parameter. Also know as Euler spiral.

Code

Defines object information. This means typically geometry, drawing and attribute data. These are stored to code files, which are divided to two separate code lists: categories and features.

Drawing

Set of properties defining object visualization. Contains information like object color, symbol, line type, size and width. Can be accessed through macros. For example, macro #COLOR returns object specific color, if defined.

Element

Single object in the Element list. May be same as file in the file system or may be just one part of the file. For example, single DWG file may contain multiple surfaces and each one of them forms separate element.

There are four element types: vector, raster, alignment and surface. Vector files may have multiple member objects. Raster, alignment and surface types contain always just one object.

Feature

String tag defining the type of the object. Refers to a code in the code file. Stored internally as an attribute, but accessed through macros #FEATURE or #CODE. For example, feature "121" may define road centerline.

Geometry

One of the following types: point, line, area, surface or alignment.

Island

Inner area within outer area boundary line. Defined as a closed line rotating opposing direction as the outer boundary. Connected to the outer boundary with hidden line segments.

Line

Line is an object containing two or more points. Each line point is technically same as single point and may have its own elevation and attributes. Term 3D polyline is often used in other systems and GIS literature.

Line may be open or closed. Closed line endpoints have same coordinates and it may be marked as an area.

Macro

Way to access properties. Upper case word starting with character #. Most macros are read-only, but some access attributes and can be used to change their values. For example, read-only macro #LENGTH just returns length of the line, but macro #FEATURE may be used to set object feature code.

Point

Point is a single 3D point with coordinates and attributes.

Property

Generic data available for object. May be either user editable attribute or calculated read-only data accessed through macros. For example, length of the line can be accessed by macro #LENGTH.

Raster

Refers to raster element type containing single raster image.

Segment

Part of the line between two points. May be either straight or arc. Segment endpoint is considered to be part of it and segment properties are accessed through it. For example, line point macro #DXY returns horizontal distance to the previous line point.

Surface

Collection of triangles forming network. Topologically well behaving triangle network has no gaps or intersections between triangles, but small inaccuracies usually do not cause problems.

Surfaces created by Rewise may contain triangles referring directly to line points. Surfaces from other external sources, use just single corner points.

Tag

Id string tag for properties. Internal Rewise properties use upper case letters, but data from external formats may contain any characters. Tags are case-sensitive and should not contain spaces. Macro tags are always prefixed with # and attribute tags may need prefix $ in some cases. For example, tag $COMMENT refers to comment attribute and tag #SLOPE to slope macro.

Triangle

Triangular plane formed by three corner points. Points may be shared between adjacent triangles and may be either single or line points.

Vector

Refers to vector element type. It may contain points, lines and areas.