Crs.Route Methods
Densifies the given waypoints into a route that follows either great circles, rhumb lines, or straight 3D lines.
Overload List
| Name | Description | |
|---|---|---|
| Public method | Route(PointCollection waypoints, LineType routeType, System.Boolean routeClosed, System.Double stepMax, System.Double greatCircleNodeErrorMax) | Returns a route between given waypoints, following either great circles, rhumb lines, or straight 3D lines. |
| Public method | Route(IEnumerable< Point > waypoints, LineType routeType, System.Boolean routeClosed, System.Double stepMax, System.Double greatCircleNodeErrorMax) | Returns a route between given waypoints, following either great circles, rhumb lines, or straight 3D lines. |
Route(PointCollection waypoints, LineType routeType, System.Boolean routeClosed, System.Double stepMax, System.Double greatCircleNodeErrorMax)
Returns a route between given waypoints, following either great circles, rhumb lines, or straight 3D lines.Syntax
public PointCollection Route (
PointCollection waypoints,
LineType routeType,
System.Boolean routeClosed,
System.Double stepMax,
System.Double greatCircleNodeErrorMax
)Parameters
A list of waypoints expressed in the Crs, with the z coordinates representing meters above sea level.
The type of the route (the type GreatCircleApprox is not supported).
Whether the route should go from the last waypoint back to the first.
Maximal distance between two adjacent route points, in meters.
Maximal distance in meters between a route point and the correct great circle.
Return Value
A refined route, with extra route points inserted between the given waypoints, tracing great circles, rhumb lines or straight 3D lines.
Remarks
Takes a list of waypoints and returns a refined route, where extra points have been inserted so that each segment between two waypoints forms a rhumb line, a great circle, or a straight 3D line. For rhumb lines and great circles, it is assumed that altitude shall vary linearly with horizontal surface distance (at sea level) along each segment.
If all you want to do is to display a great-circle route, then the GreatCircleOperator is much easier to use. However, the route method gives more control over the absolute error, which can be important if you need to do further calculations on the result. And the great-circle operator does not support rhumb lines or straight 3D lines.
Line type and accuracy
If the projection is non-georeferenced, then the returned route will contain only the given waypoints. Otherwise, the given waypoints are first unprojected to LongLat. Then, intermediate route points are computed in LongLat or in a Cartesian 3D space, with two adjacent route points at most stepMax meters apart. The route points are finally projected to the original Crs before the route is returned.
When stating the route accuracy, we must distinguish two kinds of error:
Node error: The intermediate nodes may not be on the true route.
Visible error: Even if all intermediate route nodes are exactly on the true route, the straight line segments between them may differ too much from the true route, if it is too curved in the View. Here, "straight line segment" means straight in the Projection of the View, which may differ from the Projection of the Crs that calls the route method.
Since the visible error depends on properties of the View projection, it is difficult to quantify. But you can always reduce it by using a smaller stepMax.
The node error does not depend on the View, but it depends on the choice of LineType. Disregarding the errors that may be caused by UnprojectToLongLat and ProjectFromLongLat, we have the following error bounds for the intermediate route points:
RhumbLine
The intermediate route points are less than 1 millimeter from the true rhumb line.
GreatCircle
The intermediate points are at most greatCircleNodeErrorMax meters from the true great-circle route. That is, you can choose the accuracy yourself. (Well, you cannot make it better than 1 millimeter.) If you can afford a larger greatCircleNodeErrorMax, the method should execute faster, up to a value of about 8400 meters. If you choose a value much larger than 8400 meters, the node error will nevertheless be at most 8400 meters, because this level of accuracy is not too hard to achieve. On a computer with a 3.20 GHz processor, we have measured the following computation times for a great-circle route from 0°E, 30°N to 109°E, 30°N (about 10 000 000 m) with a stepMax of 100 000 m and various values of greatCircleNodeErrorMax.
greatCircleNodeErrorMax | Time (microseconds) |
|---|---|
0.1 m | 350 |
1 m | 350 |
10 m | 350 |
100 m | 130 |
1 000 m | 95 |
10 000 m | 80 |
Great circle approx.
Not implemented, because the parameter greatCircleNodeErrorMax already gives a continuous trade-off between accuracy and speed.
Straight3D
High accuracy.
Route(IEnumerable< Point > waypoints, LineType routeType, System.Boolean routeClosed, System.Double stepMax, System.Double greatCircleNodeErrorMax)
Returns a route between given waypoints, following either great circles, rhumb lines, or straight 3D lines.Syntax
public PointCollection Route (
IEnumerable< Point > waypoints,
LineType routeType,
System.Boolean routeClosed,
System.Double stepMax,
System.Double greatCircleNodeErrorMax
)Parameters
A list of waypoints expressed in the Crs, with the z coordinates representing meters above sea level.
The type of the route (the type GreatCircleApprox is not supported).
Whether the route should go from the last waypoint back to the first.
Maximal distance between two adjacent route points, in meters.
Maximal distance in meters between a route point and the correct great circle.
Return Value
A refined route, with extra route points inserted between the given waypoints, to form rhumb-line or great-circle segments.
Remarks
Takes a list of waypoints and returns a refined route, where extra points have been inserted so that each segment between two waypoints forms a rhumb line, a great circle, or a straight 3D line. For rhumb lines and great circles, it is assumed that altitude shall vary linearly with horizontal surface distance (at sea level) along each segment.
If all you want to do is to display a great-circle route, then the GreatCircleOperator is much easier to use. However, the route method gives more control over the absolute error, which can be important if you need to do further calculations on the result. And the great-circle operator does not support rhumb lines or straight 3D lines.
Line type and accuracy
If the projection is non-georeferenced, then the returned route will contain only the given waypoints. Otherwise, the given waypoints are first unprojected to LongLat. Then, intermediate route points are computed in LongLat or in a Cartesian 3D space, with two adjacent route points at most stepMax meters apart. The route points are finally projected to the original Crs before the route is returned.
When stating the route accuracy, we must distinguish two kinds of error:
Node error: The intermediate nodes may not be on the true route.
Visible error: Even if all intermediate route nodes are exactly on the true route, the straight line segments between them may differ too much from the true route, if it is too curved in the View. Here, "straight line segment" means straight in the Projection of the View, which may differ from the Projection of the Crs that calls the route method.
Since the visible error depends on properties of the View projection, it is difficult to quantify. But you can always reduce it by using a smaller stepMax.
The node error does not depend on the View, but it depends on the choice of LineType. Disregarding the errors that may be caused by UnprojectToLongLat and ProjectFromLongLat, we have the following error bounds for the intermediate route points:
RhumbLine
The intermediate route points are less than 1 millimeter from the true rhumb line.
GreatCircle
The intermediate points are at most greatCircleNodeErrorMax meters from the true great-circle route. That is, you can choose the accuracy yourself. (Well, you cannot make it better than 1 millimeter.) If you can afford a larger greatCircleNodeErrorMax, the method should execute faster, up to a value of about 8400 meters. If you choose a value much larger than 8400 meters, the node error will nevertheless be at most 8400 meters, because this level of accuracy is not too hard to achieve. On a computer with a 3.20 GHz processor, we have measured the following computation times for a great-circle route from 0°E, 30°N to 109°E, 30°N (about 10 000 000 m) with a stepMax of 100 000 m and various values of greatCircleNodeErrorMax.
greatCircleNodeErrorMax | Time (microseconds) |
|---|---|
0.1 m | 350 |
1 m | 350 |
10 m | 350 |
100 m | 130 |
1 000 m | 95 |
10 000 m | 80 |
Great circle approx.
Not implemented, because the parameter greatCircleNodeErrorMax already gives a continuous trade-off between accuracy and speed.
Straight3D
High accuracy.
Platforms
Windows, Linux, Android