RoadType Enumeration
This enumeration represents the possible road types for TerrainRouteOperator.RoadType or TerrainAccessOperator.RoadType.
NuGet/Assembly: Carmenta.Engine.5.16.2.nupkg (in the CEOperators assembly)
Syntax
public enum RoadTypeValues
| Value name | Value | Description |
|---|---|---|
| RoadWithTerrainAccess | 0 | A ground road with access to the terrain. A terrain vehicle may enter, exit or cross the road wherever it can handle the surrounding terrain. Strictly speaking, a crossing can occur anywhere, but entering or exiting can only occur at a node of the road feature (with a few exceptions). So for some road datasets, the results may appear more natural if you densify the road features before they arrive to the terrain operator (although this may slow down the operator); see tip below. |
| RoadWithoutTerrainAccess | 1 | A ground road with no access to the terrain. A terrain vehicle may use the road but may neither enter from terrain nor exit to terrain. Nor may the vehicle start from terrain and cross the road to the terrain on the other side. But the vehicle can of course cross the road while travelling on an intersecting road. |
| Bridge | 2 | A terrain vehicle may use the bridge but may neither enter from terrain nor exit to terrain. But the vehicle may cross the bridge by going under it wherever it can handle the terrain below. |
| Tunnel | 3 | A terrain vehicle may use the tunnel but may neither enter from terrain nor exit to terrain. But the vehicle may cross the tunnel by going over it wherever it can handle the terrain above. |
| FerryRoute | 4 | A terrain vehicle may use the ferry, but may neither enter from water nor exit to water. But if amphibious, the vehicle may cross the ferry route in water. |
Remarks
A road junction – a point that is an end point of two or more roads – will allow direct access to terrain if none of the roads has the type RoadWithoutTerrainAccess and at least one has the type RoadWithTerrainAccess.
The Bridge, Tunnel and FerryRoute types are basically treated the same by the route finding algorithms. However, a route generated by TerrainRouteOperator will contain attributes giving the number of ferries that have been used. An application should use these attributes to warn about ferry usage, since the ferry schedules are not known by the operator. Also, note that the operators are not automatically reluctant to use a road feature just because it is a ferry route. To implement such reluctance, you should reserve a special worst road class for ferry routes, and define the roadClass property of your operator accordingly, and ensure that the ferry speed is slow in TerrainVehicleType.RoadSpeeds.
The road type will usually depend on several road attributes, so the TerrainRouteOperator.RoadType and TerrainAccessOperator.RoadType properties must be implemented as the kind of attribute variable that uses an expression. In the expression syntax, you must use the integers that represent the enumeration values. For example, an expression for a road dataset from HERE could look like this:
if BRIDGE = "Y"
then 2
else if TUNNEL = "Y"
then 3
else if FERRY_TYPE = "B"
then 4
else if RAMP = "Y" or URBAN = "Y" or int(SPEED_CAT) < 6
then 1
else 0
The last condition will deny terrain access from ramps, urban roads, and roads with speed limits greater than 50 km/h.
As mentioned above, you may want to densify the nodes of the road feature geometries, but there is no built-in operator that only densifies line geometries. If you do not want to pre-process the road dataset or define a custom operator, you can use a ProjectOperator with ProjectParameters.EdgesToSegmentize = All and a small value for ProjectParameters.EdgeLengthMax, say two or three times the resolution of the terrain rasters. However, to activate the segmentization, you must use an explicit ProjectOperator.Crs that differs from the CRS of the road dataset. The predefined Crs.Wgs84MercatorWeb should usually work since roads are seldom stored in this CRS, and the projection formulas are fairly efficient and work globally. Even better would be to use a new CRS instance constructed from GeodeticDatum.Wgs84 and a new instance of EquidistantCylindricalAngularProjection with default parameters.
Platforms
Windows, Linux, Android