Skip to content

Close Polygons

The command Close Polygons on the Extras menu enables to generate from individual polygon lines imported as auxiliary polygons into CadnaA (e.g. from AutoCad) a closed polygon. Simultaneously, the closed polygon is converted into the object type "Building".

In case of a different target object than a building, convert the building polygons after import (see Convert to in the manual „Introduction to CadnaA“).

Example

In the initial situation, after import of auxiliary polygons, they do no match and create buildings since the data shows gaps between polygons:

Initial situation: individual lines (Auxiliary Polygons) after import, not forming closed buildings

Proceed as follows:

  • Import (see Chapter 7 - Import) the data using a suitable file format.
  • Make sure that the „open“ buildings are imported as „Auxiliary Polygons“.
  • After import delete or deactivate the objects not forming the building‘s outer borders.
  • Select the command Close Polygons displaying a settings dialog:

Dialog options

Snap Coordinates to (m)

This value determines the stepping of the coordinates of the buildings after conversion (default: 0.01 m).

Enlarge open polygons (m)

By this value it is decided whether neighboring points of two polygons whose coordinates are not at the same coordinate will be joint or not (default: 0.00 m).

Option "Combine polygons"

When this option is activated, the individual polygons making up a building will be combined to a polygon group (i.e. "building block"). With the activated option „Combine Buildings“ terraces are combined to a single Building Indoor walls will be replaced by with barriers lying inside. Activating this option may result in a reasonable reduction of the file size in case of large numbers of objects.

Option "Delete Input-Polygons"

When this option is activated, the original auxiliary polygons will be deleted after having been converted into buildings.

In this example, the gaps are 2.5 m at maximum. So, this is used for input for „Enlarge open polygons (m)“ showing the following result:

Final situation: The buildings form now closed polygons.

After combining the lines to generate a closed polygon and converting them into buildings, the original ID is overwritten by an identifier containing the character L and a number, e.g. L1, L2, L3 etc. These new IDs indicate what happened while connecting and combining auxiliary polygons to buildings or barriers.

with

  • L1: detached building or barrier
  • L2: building inside a building or barrier inside a building
  • L3: building inside a building inside a building or barrier inside a building inside a building etc.

Based on these IDs, grouping can be used to verify that all conversions and connections were accomplished successfully.