# Assign Model UWG Properties ![](/files/-MihraCXjm1txDG9AwWh) ![](/files/-Ma9gLoT5SuIJJLKUJ-J) - [\[source code\]](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. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.ladybug.tools/dragonfly-primer/components/6_alternativeweather/assign_model_uwg_properties.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.