The event table is actually an attribute table, in which each record represents an event. In addition to the routing identifier field and the scale field, it can also contain other Attributes used to describe the event.
SuperMap desktop provide functionality for basic operations on event table, such as Generate Event Table, Overlay Event Table, and Merge Event Table.
Instructions for use
Generate Event Table is the process of generating a property table containing point or line events. The event table can be entered manually, or it can be combined with the Route Dataset Generate Event Table through an existing point or Line Dataset.
- One is to manually create an attribute table, add the routing identifier field, scale field and other Property Fields, and input the corresponding Attributes to Generate Event Table. Although this method is simple, it often requires more manpower and material resources.
- Another way is to automatically Generate Event Table through point or line Spatial Data (called Event Data) and Route Data for reference. The metric value of the generated event and the route on which it is located need to be obtained from the Route Data.
Refer to the Event table overview for a detailed description of the point and line event tables.
Function entrance
- In the Traffic Analysis tab-> Dynamic Segmentation group, click the Dynamic Segmentation button and click the Generate Event Table button in the drop-down menu.
- Toolbox-> Traffic Analysis-> Dynamic Segmentation tool: Generate Event Table; or drag the tool to the Model Builder Window and double-click the function graph.
Parameter Description
- Event Data: Set parameters related to Event Data. Select the point (or line) Event Data here, and set the Datasource and Dataset where the Event Data is located.
- Route Data: Set parameters related to Route Data. In the Route Data Settings area, select the Datasource, Dataset, and Route ID fields where the Route Data is located.
Route ID Field: Set the route ID Field, which is used to store the ID of the corresponding Route Data.
- Result Data: Set the parameters related to the result. In the Result Data Settings area, select the Datasource, the name of the event table, the routing identifier Field, the scale Field, and the Other Parameters to save the generated event table.
Route ID field: Set the name of the route ID field in the generated event table. This field is used to record the location of the event table on a certain route. The event table is related to the Route Data through the route ID Select Fields. Wherein the route ID in the event table is in one-to-one correspondence with the route ID in the Route Data.
Scale Field: Set the scale Field of the Result Event table, which is used to record the scale value (M value) of the point on the route. For the line event table, the start and end scale fields need to be set separately. Wherein the start scale field is used for storing the corresponding scale value of the starting point of the line event on the route, and the end scale field is used for storing the corresponding scale value of the end point of the event on the route.
Find Radius: Sets the find radius and unit. The buffer area extended by LineM with this value as the radius is called the search range, and the point or line objects outside this range (including some outside the search range) will not be able to generate records in the event table. Whether the point object or line object is within the search range depends on whether the Straight-line Distance from any node on the point object or line object to the route is within the search range. Taking the line event table as an example, if the Straight-Line Distance from a node of the line object to the route is greater than search radius, the line is considered to be out of the search range. On the contrary, when the Straight-Line Distance from the All Node to the route on the line object is less than search radius, the corresponding line event will be generated even if part of the line is outside the search range (which may be caused by the winding or turning of the Route Data). After setting the unit, when Generate Event Table, Application will convert the value of the search radius to be consistent with the Unit of the reference Route Data of Generate Event Table.
Create Distance Field: This parameter is only valid for point event tables. Used to set whether to generate a distance field. The distance field is used to store the straight-line distance from the point to the route. Default Create Distance Field.
Find only the closest route: This parameter is only valid for point event tables. Used to set whether to find only the most recent route. If this item is selected, when a point is within the search range of multiple routes, only the event on the route closest to this point will be generated; if this item is not selected, the corresponding event will be generated as long as this point is within the search range of the route. For example, when a point is within the search range of three routes, if only the Closest Distance route is searched, only one event record will be generated in the Result Event table; otherwise, three event records corresponding to the three routes will be generated. By default, only the most recent route is logged.
Reserve custom field of event dataset: It is used to set whether to reserve all Property Fields in the Event Data except System Field: in the Result Event table. Custom fields for Event Data are reserved by default.
- When you are ready, click the Execute button to perform this step.
Remark
- Parameter Settings are slightly different when creating a line event table and a point event table. When creating a line event table, you need to specify the start scale field and the end scale field in the generated event table; when creating a point event, you only need to set one scale field in the generated result. For the setting of Other Parameters, refer to the operation steps for creating the point event table.
- The appropriate search radius is of great practical significance to the creation of event tables. In practical applications, if the search radius is set too large, there is no practical analysis significance, and the scale value of the event table may not be ideal. Therefore, it is recommended to enter a reasonable search radius when Generate Event Table.
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