OpenSite Designer

Feature Types

Terrain Model Features

The concept of feature types is used throughout the Terrain Model tools.

Feature Type Description

Spot or Spot Elevation

Points (with X,Y,Z data) that have no functional relationship to any other point. Random survey shots in open terrain would be an example of random spots. Point elements such as cells, circles, and text strings are typical MicroStation elements used to graphically define spot elevations. Lines, line strings, and other longitudinal elements are equally valid. The software creates a spot elevation for each vertex of each longitudinal element.

Break Line

Breaks are used to designate linear features such as edges of pavement, ditch bottoms, ridges, etcetera where an abrupt change of slope occurs. Any longitudinal element may be defined as a break line. Triangles will not cross a break line in the terrain model.

Soft Break Line

A soft break line is a break line, however, if it crosses a break line, it will not affect the triangulation and is ignored.

Contour

Element or set of elements of the same elevation. Contours may be used as source data to generate a terrain model, or may be computed (drawn based on terrain model). Contour interval is the elevation difference between two adjacent contours.

Hole

An area defined by a closed shape that demarcates a region where the current terrain is ignored and the underlying terrain is utilized.

Boundary

The external boundary of the surface.

Drape Boundary

A surface boundary that determines its elevations by draping on the underlying surface.

Void

An area defined by a closed shape that demarcates a region of missing data or obscure areas. No point or break data located within the void area is utilized and no triangles are created inside the void areas. The Void coordinates are included in the triangulation and void lines between successive void coordinates are inserted as drape lines on the surface. Therefore, they do not change the slope or elevations of the surface.

Drape Void

An area defined by a closed shape that demarcates a region of missing data or obscure areas. No point or break data located within the void area is utilized and no triangles are created inside the void areas. In the drape void, the void coordinates are not included in the triangulation. Voids are inserted post triangulation. The void coordinates and lines are draped on the terrain model surface. Even though a user must provide an elevation for Drape Void vertices, the user elevations are changed to the elevation of the terrain model surface at the XY Drape Void coordinate position.

Break Void

An area defined by a closed shape that demarcates a region of missing data or obscure areas. No point or break data located within the void area is utilized and no triangles are created inside the void areas. It differs from Voids and Drape Voids in that it utilizes the vertex elevations of the graphical element, while the void lines between successive void coordinates are inserted as break lines. Therefore, break voids change the slope and elevations of the surface.

Island

An area defined by a closed shape that demarcates a region of data wholly within a void. Example, islands in the middle of rivers, lakes, etcetera.