Clarifications on curbs and other boundaries with a height

[clemenshabedank]

modifications and clarifications for curbs and other lane boundaries having a 'height'

Signed-off-by: Habedank Clemens qxs2704@europe.bmw.corp

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This PR is a suggestion which was preceded by discussion in the Road Model WP. It is basically reasoned by certain unclarities in the current definition of curbs:

• Do the boundary points describing a curb lie "inside" the curb on the level of the lower side of the curb? Because a lane boundary has a width going to the left/right from its middle...
• In wich direction points the height? Currently there is no surface definition (see Add Longitudinal Rotation of Lane Boundaries #436)
• Is it allowed to have a lane boundary of type curb referenced from the left and the right lane? Should this take the height of the curb into account (e.g. for sidewalk yes, for normal driving lane no)?

This definition tries to fix those unclarities and needs to be seen in combination with #600

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[clemenshabedank]

With the latest change in 6526e0a this PR is seen more as a bugfix to the current definition, because modelling curbs with only one laneboundary of type curb and a height field makes the height of adjacent lanes ambiguous. This PR makes it clearer that a curb must be modelled with two laneboundary's while deprecation of TYPE_CURB can of course be done in v4.0 earliest.

[clemenshabedank]

The basic issue is now resolved by #634. This PR can be closed by future Road Model work if not seen helpful.

[clemenshabedank]

The basic issue is now resolved by #634. This PR can be closed by future Road Model work if not seen helpful.

[clemenshabedank]

The basic issue is now resolved by #634. This PR can be closed by future Road Model work if not seen helpful.