4.6.1. Feature version filterΒΆ
The 3D City Database supports storing multiple versions of the same feature to enable object histories. The object history is captured based on timestamps values for the creation and termination date of a feature version, which are stored in the CREATION_DATE and TERMINATION_DATE columns of the CITYOBJECT table.
Using the feature version filter, a user can choose which version of the top-level features should be selected in a visualization export operation.
The default option Latest version will only select those top-level features
that have not been marked as terminated in the database and, thus, whose
TERMINATION_DATE is null
. When switching to Valid version, you can specify that only
features that were valid at a given timestamp or for a given time range should
be considered. This is done by evaluating the CREATION_DATE and TERMINATION_DATE
values in the database against the specified filter values. For example,
you can use Valid version to create a visualization of a past status of your 3D city model
(e.g., at March 1st, 2018) and compare it to a visualization of the current version.
Note
For the feature version filter to work correctly, you must make sure that the validity times of subsequent feature versions do not overlap. The Importer/Exporter does not provide specific tools for managing feature versions in the database.
Hint
If your 3D City Database does not contain multiple feature versions, you should always disable the feature version filter to avoid unnecessarily complex SQL queries.