4.5.8.7. <appearance> parameter

The <appearance> parameter filters appearances by their theme. To keep an appearance in the target dataset, the value of its app:theme attribute simply has to be enumerated using a <theme> subelement. The string values must match exactly.

The app:theme attribute in CityGML is optional and thus can be null. To be able to also express whether appearances having a null theme should be exported, the <appearance> parameter offers another subelement <nullTheme>, which is of type Boolean. If set to true, appearances with a null theme are exported, otherwise not (default).

The following query exports road features and appearances with theme summer and winter. Since <nullTheme> is set to false, appearances lacking an app:theme attribute are not exported.

<query>
  <typeNames>
    <typeName>tran:Road</typeName>
  </typeNames>
  <appearance>
    <nullTheme>false</nullTheme>
    <theme>summer</theme>
    <theme>winter</theme>
  </appearance>
</query>