Creation of risk maps
Note
This document has been machine translated.
Common specifications for risk map data
A risk map is a time attribute (start and end dates and times) and a spatial attribute (polygons), a set of records consisting of risk values observed (or predicted) in that time and space.
A risk map consists of the following columns
| Column Name | Data Type |
|---|---|
| start_datetime | timestamp with time zone |
| end_datetime | timestamp with time zone |
| geom | geometry |
| risk | integer |
-
start_datetime / end_datetime: time attribute
The start and end date and time are recorded in 5-minute increments.
-
geom: Spatial attribute
The geometry of the corresponding mesh is recorded in either the standard regional mesh (primary to tertiary mesh) or the segmented regional mesh (one-half regional mesh and one-quarter regional mesh). Specify which granularity of mesh to use when retrieving the risk map.
-
risk: Risk value
The rules obtained from the correlation rule extraction are applied to the real data, When you apply a rule obtained by correlation rule extraction to real data, you will get some value for a certain time and place based on the rule. In EvWH, we can obtain the likelihood of traffic congestion from precipitation, to extract rules to obtain the dispersion of air pollutants from temperature and humidity, The obtained values are called “risk values”. Risk values are defined on a scale of 0 to 10 on an 11-point scale.
riskmap metadata
The riskmap.metadata table is used to map theme names to riskmap table names.
| column name | data type | description | whether used in route finding |
|---|---|---|---|
| id | integer | Unique ID (primary key) | |
| creatorname | text | Author | |
| theme | text | Theme Name | 〇 |
| language | text | Language | |
| version | text | Version | |
| table_name | text | Table Name | 〇 |
| description | text | Risk Map Description | |
| provenance | text | Provenance Information | |
| created_datetime | timestamp with time zone | Creation Date | |
| start_datetime | timestamp with time zone | Scope of risk map (start date) | |
| end_datetime | timestamp with time zone | Scope of risk map (end date/time) | |
| geolocation | geometry | Scope of risk map (spatial extent) | 〇 |
The riskmap.metadata table has the above definitions, but only the columns marked with “0” are used in the route search process.
The geolocation column is used to narrow down the scope of the search. If a risk-averse route search is specified, areas not covered by the riskmap (because the risk is unknown) are excluded from the route search candidates.