Obstacle

The obstacle map defines a Boolean attribute that guides the creation of street networks.

Obstacle Map

The typical usage scenario is to create a land-water map where the water is marked in a dark color (i.e. brightness below 0.5) and the land in bright color. The obstacle attribute layer can then be selected in the automatic street generation wizard and streets are generated accordingly (i.e. no streets in dark regions).

Create an obstacle map via Layer→New Map Layer... in the main-menu, and choose Obstacle.

Obstacle Dialog

Bounds Dimensions: The Width and Height of the resulting texture in meters. When a georeferenced image is selected, this value is set automatically.

Bounds Location: The location of the resulting texture in meters. When a georeferenced image is selected, this value is set automatically.

Note that the button right of Location can be used to change the reference point of the obstacle's position.

 

Obstacle Layer in CityEngine scene

After the type "Obstacle" has been selected in the Wizard the obstacle attribute layer can be created as follows:

  1. Browse your project and select the image map. Note that only image maps in the workspace can be selected. Therefore the image has to be copied or imported into corresponding project folder (typically "maps").
  2. Select the source channel and the corresponding threshold. Values below the threshold are interpreted as obstacles.
  3. Set the dimensions and location of the attribute layer in the scene.
  4. Click finish.


Street network generation controlled by an obstacle map

As a result an obstacle attribute layer is selected where the channel threshold function is represented as a function returning a Boolean function. This function and all other attribute layer properties can still be edited after creation.

NOTE: All attribute layer functions that evaluate a Boolean value such as the obstacle layer can also be used for selecting objects in the scene by choosing Select from the context menu. See also Selection via Image Maps.

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