4.5.8.10. Address information

The 3DCityDB comes with a CityGML ADE that allows a simple use of address information and metadata columns in XML queries. The following table shows the XML namespaces to be used with CityGML version 2.0 respectively 1.0 and the recommended XML prefix of the 3DCityDB ADE.

Table 4.12 XML prefix and namespace of the 3DCityDB ADE.

ADE	XML prefix	XML namespace
3DCityDB ADE	citydb	http://www.3dcitydb.org/citygml-ade/3.0/citygml/2.0 http://www.3dcitydb.org/citygml-ade/3.0/citygml/1.0

CityGML uses the OASIS xAL standard for the representation of address information. xAL is very flexible in that it supports various address styles that can be XML-encoded in many ways. As a drawback, this flexibility makes it difficult to define a filter on address elements (e.g., the street or the city) using an XPath expression based on xAL. When importing address information into the 3DCityDB, the xAL address fragment is parsed and mapped onto the columns STREET, HOUSE_NUMBER, PO_BOX, ZIP_CODE, CITY, STATE and COUNTRY of the ADDRESS table. Thus, it is much simpler to express filter criteria on these columns.

For this reason, the 3DCityDB ADE injects additional properties into the core:Address feature of CityGML that correspond to the columns of the ADDRESS table. By this means, these properties can be used in filter expressions. The mapping between ADE properties and columns of the ADDRESS table is shown below. Note that the citydb prefix must be associated with the ADE XML namespace (see above). If omitted, the CityGML 2.0 namespace is assumed given that the prefix citydb is used.

Table 4.13 3DCityDB ADE properties for accessing address information.

ADE property (injected into core:Address)	Data type	Column of the ADDRESS table
citydb:street	xs:string	STREET
citydb:houseNumber	xs:string	HOUSE_NUMBER
citydb:poBox	xs:string	PO_BOX
citydb:zipCode	xs:string	ZIP_CODE
citydb:city	xs:string	CITY
citydb:state	xs:string	STATE
citydb:country	xs:string	COUNTRY

The following example illustrates how to query all buildings along the street Unter den Linden. It uses the citydb:street ADE property as value reference in the filter expression.

<query>
  <typeNames>
    <typeName>bldg:Building</typeName>
  </typeNames>
  <filter>
    <propertyIsLike wildCard="*" singleCharacter="." escapeCharacter="\" matchCase="true">
      <valueReference>bldg:address/core:Address/citydb:street</valueReference>
      <literal>Unter den Linden*</literal>
    </propertyIsLike>
  </filter>
</query>