# Assign Model UWG Properties

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![](https://3405893330-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-Ma9gBkJelXEQ5LsYEl7%2Fuploads%2Fgit-blob-245f75a9fe8495415bff216d20921b35002d8f07%2FAssign_Model_UWG_Properties.png?alt=media) - [\[source code\]](https://github.com/ladybug-tools/dragonfly-grasshopper/blob/master/dragonfly_grasshopper/src/DF%20Assign%20Model%20UWG%20Properties.py)

Edit the properties of a Dragonfly Model that affect simulation with to the Urban Weather Generator (UWG).

## Inputs

* **model \[Required]**

  A Dragonfly Model which is to have its Urban Weather Generator (UWG) properties assigned. 
* **terrain**

  A Terrain object that dictates the properties of the street and ground beneath the buildings. If None, a default terrain object will be generated by analysing all of the buildings in the Model and drawing a bounding rectangle in the XY plane around them. 
* **traffic**

  A TrafficPararameter object that defines the activity and intensity of traffic within the urban street canyons. If None, traffic intensity will be approximated using the average building story count along with a generic traffic schedule. 
* **tree\_cover**

  A number from 0 to 1 that defines the fraction of the exposed terrain covered by trees. If None, it will be determined by evaluating the horizontal area of all ContextShade geometry that has a true is\_vegetation property. 
* **grass\_cover**

  A number from 0 to 1 that defines the fraction of the exposed terrain that is covered by grass or shrubs. If None, no grass will be assumed for the urban area. 

## Outputs

* **report**

  ... 
* **model**

  The input Dragonfly Model with its UWG properties re-assigned based on the input.