# Point-based building (Water Overlay)

Point based buildings are constructions for which their geometry is interpreted as a single point.

Examples of point based buildings are the following hydraulic structures:

Icon | Name | Name |
---|---|---|

Inlet | Conditional flow from external area to inlet location. | |

Sewer overflow | Conditional flow from sewer to waterway, based on sewer overflow height. |

## Center point

A method to obtain a point from a geometry is to calculate the geometric center point of a geometry. The method used by Tygron Platform is similar to [1]. See the following examples:

The method above is simple, but not robust in all cases. See the following two cases:

In case one, the building's geometry is a complex polygon. Its centroid lies outside its geometry.

In case two, the building's geometry is a multi-polygon. Its centroid is in between the two rectangle polygons.

Generally, these kind of polygons are undesirable for a point-based building.

## General advice

- The point-based buildings should be supplied as simple rectangle or circular polygons.
- The geometry should consist of only one polygon. In the case of buildings, use only one section.

## See also