Calculating building height from 3D BAG

Input data

The input data for this processing step is obtained from a WFS connection to the 3D Basisregistratie Adressen en Gebouwen (BAG) dataset. See this page for more details.

Main steps

Filter out buildings with invalid height

Filtering out buildings with invalid height

Create a filter on the 3D BAG layer to remove any buildings which do not have a valid height. A filter can be added by right clicking on the layer and navigating to Filter... and typing the following expression:

"height_valid" = 'true'

Calculate building height

Calculating building height

Calculate the building height based on the difference between the roof height and ground height of each building.

1. Open the field calculator of the 3D BAG layer
2. Create a new field called “height” and ensure that the output field type is set to “Decimal number (real)”
3. The following expression can be used to calculate building heights rounded to whole meters and to exclude anything below 4m:

ROUND(IF("roof-0.95" - (IF( "ground-0.00" IS NULL, 0, "ground-0.00" )) <= 4, NULL, "roof-0.95" - (IF( "ground-0.00" IS NULL, 0, "ground-0.00" ))))

Set z-value of building geometry

Setting the z-value

• Select the Toolbox (gear icon)
• Search for the tool: "Set Z value"
• Select the 3D BAG layer as input and change the "Z Value" input by selecting: Field type: int, double, string > <your building height field> (double)
• Choose a name and file path for the "Z Added" layer
• Run the tool. The output is a new layer in which the building height attribute has been linked to the z-component of the polygon geometries. This is the layer that should be used for any further visualisation / processing steps.