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Line-like Objects

Line-like objects (e.g. line source, road, railway) are defined by a sequence of polygon segments or, respectively, by a sequence of points making up the polygon. The first and the last point of the polygon may have the same or a different height (being relative, absolute or relative heights referring to a building roof). In this case, the height of intermediate polygon points is determined by linear interpolation (option „Interpolate Height from First/Last Point“). Alternatively, for each point of the polygon may a different absolute height may be defined.

Note

For contour lines the entered height (z) is always interpreted as an absolute height.

Dialog Geometry of a Line Source

Dialog Options Polygon: Geometry

List of polygon points: Shows the coordinates x, y, z and the ground height at the respective point. A double-click into a table row opens the dialog Polygon Point. Using the command from the context menu of the table offers - for example - to delete or insert polygon points.

List Box Height

option „Interpolate Height from First/Last Point“:

  • relative: height in meters (m) above terrain level at the coordinate (x, y). The (absolute) height of the ground results from:
  1. the height of objects forming terrain (contour lines, height points, lines of fault),
  2. from the standard height specified on "DTM" tab (menu Calculation|Configuration, see DTM Digital Terrain Model Tab) and
  3. by the method applied to from terrain between the objects defining terrain height (e.g. by triangulation).
  • absolute: Height above a reference plane, as a rule above mean sea level (MSL). The MSL height does necessarily correspond for different, even neighboring countries since different definitions and references are used.
  • Roof: This option facilitates the input of a height for sources on top of a building's roof. The relative height above the roof plane is entered. For a source within the building's border the source height results from the sum (building height + height above roof).

option „absolute Height at every Point“: When this option is selected the absolute height Z can in addition be edited in the list of polygon points or via the dialog Polygon Point.

option „absolute Height/Ground at every Point“: When this option is selected the ground height, besides the absolute height Z, can be edited in the list of polygon points or via the dialog Polygon Point.

2D-Length

length of the polygon projected into the xy plane

Station

In order to generate station marks alongside of line-like objects an initial station value (in meters) can be specified (see Station Box). The option "ascending/descending" defines as to whether the stationing starts increasing or decreasing from the present location.

Additional information for objects „vertical area source“ and „barrier“

Initially, when entering the objects „vertical area source“ (see Industrial Sources) and „barrier“ (see Barrier) in the graphics, these are represented by a 2D polygon having no height. The height (or the z-coordinate) of the polygon points for these objects (as entered via the Polygon: Geometry dialog) refers to the top edge of the object. The other dialog options comply with those for line-like objects in general.

vertical area source & barrier: z-extension

With floating barriers, the z extend (see Floating Barrier) describes the vertical height difference of the lower edge to the top edge as entered on the dialog Polygon: Geometry.

Note

The z-extend counts positive downwards!

Consequently, the bottom and top edge are always parallel and cannot be distinguished in the 2D-plan.

z-extend of a floating barrier: In this example, the barrier extends at all polygon points 3 m downwards from the top edge.

Additional information for object „Vertical Grid“

When entering the object „Vertical Grid“ (see Vertical Grid) a height of the top edge of 20 meters is set by default. The object can consist of two points only (see dialog Polygon: Geometry). Further polygon points will be ignored.

Height Extend of the vertical Grid

The vertical grid extends from the height of the top edge (as specified on dialog Polygon: Geometry) down to the ground. Grid points below the terrain, however, are not displayed in the grid. Depending on the grid spacing, this causes more or less white areas on the vertical grid.

Flat terrain: The vertical grid extends to the ground.
The dots indicate the grid points (grid spacing (1 by 1) m.
Non-flat terrain: The vertical grid (spacing (1 by 1) m also extends down to the ground, but grid areas where the grid point is below the terrain profile are not displayed (white color).
same as above, but now with a coarser grid spacing of (5 by 5) m.
Again, the grid areas where the grid point is below the terrain profile are not displayed (white color)

Additional Dialog Options for Road & Rail

Besides the default geometry options of line-like objects, there are additional dialog options available for the objects „Road“ (see Common Input Data) and „Railway“ (see Common Input Data).