WMSTime Layer

c2cgeoportal supports WMS Time layers.

When the time is enabled for a layer group (a layertree group, not a wms layer group), a time widge (a slider or datepicker) is added to this group in the layer tree which enables changing the layer time.

Configuration

Most of the configuration is automatically extracted from the mapfile. But there is also some configuration to do in the administration interface.

Mapfile

In the mapfile, a WMS Time layer is configured with the help of the layer metadata:

  • wms_timeextent

  • wms_timeitem

  • wms_timedefault

If the time layer is a wms layer group, the metadata are extracted from its children.

c2cgeoportal uses the wms_timeextent to configure the slider. Two different formats are supported to define the time:

  • min/max/interval

  • value1,value2,value3,...

The format min/max/interval allows specifying a time range by giving a start date, an end date and an interval between the time stops.

The format value1,value2,value3,... allows specifying a time range by listing discrete values.

The dates (min, max and valueN) can be specified using any of the following formats:

  • YYYY

  • YYYY-MM

  • YYYY-MM-DD

  • YYYY-MM-DDTHH:MM:SSTZ (TZ is an optional timezone, i.e. “Z” or “+0100”)

The format used for the dates in the mapfile determines both the resolution used for the slider and the format of the time parameter used for the GetMap requests. For example, when a layer has monthly data, the YYYY-MM should be used in the mapfile to make sure that only months and years are displayed in the slider tip and passed to the GetMap request.

The interval (interval) has to be defined according to the ISO 8601 standard and its duration/time intervals definition (see ISO 8601 Durations / Time intervals).

Some examples for the interval definition:

  • An interval of one year: P1Y

  • An interval of six months: P6M

For more information, please refer to the MapServer documentation.

Admin interface - widget

Most of the configuration is done in the mapfile as described in the above section. However the time widget must be configured via the admin interface. Two different widget types are available: a time slider and a datepicker widget. The preferred widget can be selected in the admin interface (field Time widget).

Note that the time mode can be changed. The time mode is one of:

  • value

  • range

  • disabled

The value mode displays a widget to select a single time or date. For a slider widget, a slider with a single thumb will be displayed. If datepicker is selected as widget, a single datepicker will be shown to select a single date. The WMS Time layer will display data that is relative to the selected time or date.

The range mode displays a widget to select a time range. For a slider widget, a slider with two thumbs is shown. For the datepicker widget, two datepicker fields are displayed to select the start and end date. In mode range the layer will display data that is relative to the defined range.

The disabled mode hides the time widget. No time parameter will be sent to the GetMap request in this case.

Admin interface - query

By setting a timeAttribute metadata having as value the attribute used in the OGS server as time item, you ensure that the WMS/WFS queries take into account the time filtering values and that no result is returned if an object is hidden by the time filter.

Merging configurations

The previous section describes the time configuration for a single layer. However there could be multiple WMS Time layers in a group. In such a case, you need to be aware of some limitations that apply to the configuration of the WMS Time layers of the same group.

Some of those limitations apply to the mapfile:

  • The WMS Time layers of a same group must all be configured with either a list of discrete values or an interval. It is not possible to mix the two different types of definition within the same group,

  • If the WMS Time layers of a group use the min/max/interval, they must all use the same interval.

There is also a limitation that applies to the admin interface: all the WMS Time layers of a group should be configured to use the same widget and the same time mode (single or range), except for layers with time mode disabled, which can be mixed within others.