Storage of time data
SuperMap maps can play and display Temporal Data stored in UDB/UDBX Datasource, PostGIS database, Oracle database, etc.
The attribute table of Temporal Data shall have a time field for storing time information, and each element in the table may have a time field representing an observation time point, for example, for a typhoon track point element, the time field represents a typhoon observation time; You can also have two time fields that represent the Start and End Time of the observation, for example: a face feature that represents a flood extent has a Start and End Time.
Handling of time fields
The time field of Temporal Data must be date type to achieve better query performance. If the time field of your data is not a date type, you must roll over the time value in the non-date type field to the date type field.
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| Figure: Time field in Temporal Data |
In general, the time value of Temporal Data may be stored in a text, string or numeric field. SuperMap provides a function to convert the time value in a text or string field (numeric type is not supported at present) into a date type, but the time value recorded in the field must conform to a specific time format. In order to convert successfully.
- Supported time value string formats: YYYY, YYYYMM, YYYY/MM, YYYY-MM, YYYYMMDD, YYYY/MM/DD, YYYY-MM-DD, YYYYMMDDhhmmss, YYYY/MM/DD HH: mm: SS, YYYY-MM-DD hh:mm:ss。
- Where: YYYY = four-digit year; MM = two-digit month (01 = January); DD = two-digit day of the month (from 01 to 31); HH = two-digit hour (from 00 to 23) (A. M./P. M. Not supported); mm = two-digit minute (from 00 to 59); SS = two-digit seconds (from 00 to 59)
Time values in non-date type fields are transferred to date type fields as follows. For more information on the function of field Type Conversion, see " Update column ".
- Open the property sheet in which the time field resides, and create a date-type field for the property sheet to store the converted time value.
- Use the Update Column function in the newly created date type field and set the update parameters:
- Select Whole Field ";
- Select "Function";
- Select the operation field as the field storing the time value, here it is "Time", which is the wide character field storing the time value;
- Select "to _ date" as the operation function to convert to the date function, and specify the time format of the time field to be converted, that is, what rules are used to record the time values such as year, month, day, hour, minute and second. Refer to the above "Time Value String Format" for the supported contents. Here, the time field records the time value using the "YYYY/MM/DD HH: mm: SS" format.
- Type conversion is completed through the above operations.
In addition, you can index date-type time fields to further improve visualization and query performance.
Format of Temporal Data
Both Vector Data and Image Data with time attribute can be played and displayed in SuperMap. Image Data needs to be added to Mosaic Dataset before it can be played and displayed in the map.
- Vector: Vector Data can express the geographic information that the shape and position of Geometry change over time. For example, if the track of a typhoon over time is recorded, each point in Vector Data is the position of the typhoon at a certain time, and the time field records the observation time of the position. When Temporal Data is displayed, the typhoon track points at the corresponding time are displayed in turn according to the time line played. of Typhoon Track Point
Figure: Temporal Data - Image: The image must be added to the Mosaic Dataset. Use the Mosaic Dataset's Contour Dataset Properties table to store the time value of the image.
First, create a Mosaic Dataset and add the target multi-temporal image to the Mosaic Dataset. Then, in the Mosaic Dataset profile Dataset Properties table, create a new date-type field to store the time value. The number of new time fields is determined according to the time characteristics reflected by the image. For example, if the image is the observation result of a time period, two time fields, the start time field and the end time field, need to be created. Finally, edit the time field and fill in the time value corresponding to the image. As shown in the figure below, Mosaic Dataset adds the satellite cloud images at each observation time of a day, and records the observation time of the cloud images in the Time field of the profile attribute table.
to the Profile Dataset Properties Table
Figure: Adding a Time Field
Add Temporal Data to Map
Temporal DataAdd to Map, and set Layer Style. For Style Settings, see Set the style of the layer . In addition, when playing Temporal Data in the map, it is recommended to add the non-Temporal Data layer to the snapshot layer for management. In this way, when playing Temporal Data, it can effectively improve the refresh display efficiency of the map and make the playback display more smooth.
Snapshot layer , multiple layers contained in this layer group will be used as a snapshot layer of the map. The snapshot layer is only drawn when the map view range changes. When playing Temporal Data, the map view range usually does not change. The entire map display simply refreshes the layers that change over time, resulting in faster performance and smooth interaction.
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