====== 2. Main Section: Building Height ======
If the [INTERNAL] format is used, the header is followed by the main section defining the position and height of **buildings**.\\
[[Example Building Top|Click here to see an example section]]\\
The format chosen in the first line of the file ([[Format ID]]) is used here. Buildings are set into the area by assigning their height to the corresponding grid points ("**20**" in the [[example building top|example]]).\\
Only integer values are allowed as height information.

ENVI-met will assign the building to the corresponding grid boxes. In the vertical direction, the following rule is used to decide if a grid box is occupied by a building or not: If a grid cell is covered 50% or more by a building, it becomes part of the building. In the other case, it remains free.  


<fs smaller>**Example**\\
A 14m high building covers 3 grid cells with Δz=5m (split surface grid not counted).\\
Contrary, a 12m building will only be represented by 2 grids in the vertical.</fs>

 

=== Avoiding Captured Grids ===

Captured grids can cause problems in the model simulation.\\
A "captured grid" is a free grid cell that is surrounded by occupied grid cells only.\\
[[CAptured Grids|Click here to see an example for captured grids]]