Alignments from polylines. Chained stationing

Civil 3D
1

Hi, I’m working with several polys that I’m willing to convert into alignments. One poly will be the main (1st order) and the rest of polys will intersect the main or each other and (here’s the part where im a little lost) take the intersecting stationing as start stationing of itself

Here is some visual support:
Alineamientos de polilineas.dyn (221.3 KB)
red-main poly
white-rest of polys

image
image1436×1030 105 KB

This is what i have worked so far, but as you can see, there are some incorrect intersections as the stationing is not cotinuous
image
image1092×882 62.5 KB

image
image928×758 46 KB

I feel like this should be some kind of a loop of by discarting the already used polys but I have no clue how to do this. :upside_down_face: help please

2

In traditional programming, this would use a Stack list where you add and remove each polyline as you process it, so that you can process subitems of the polyline without inadvertently reprocessing a previously stacked item. You would then store the processed items into another Stack.
I’m not sure how to use this concept in dynamo or if it’s a valid methodology.

1 Like
3

I have 0 knowledge about programing (I had a hard time to include a for loop in DesignScript :face_with_head_bandage:). Mehtodology sounds valid but I would not know how to implement it

4

For a ‘stack’ method like you mention can use imperative design script, or you can use Python, or a custom node. Things are usually doable with nodes too though.

Assuming the ‘goal’ is to always have station 0 (start point going forward) of each polycurve closest to the original alignment (red object in the sketch) you can actually do this in a really fun way with VASA. (ok fun might be a relative term here… I am a nerd and if you are too you might enjoy this).

  1. Ensure all polycurves (including the base) are on the XY plane (.
  2. Extrude them on the Z axis by 1 unit to get a list of surfaces
  3. Union the surfaces into a PolySurface.
  4. Build a Voxel model of the resulting polysurface. You can use a DisplayVoxels node to see what this looks like, and you’ll have to scale things to your needed level of detail. For starting out I recommend 1 for the size, for the vertical resolution, and 0 for the level of development. The dimension may want to jump up to 3 or 10 or 5 or other dimension as you up scale the scope.
  5. Build a path model from the voxel model, setting the expand extents for true so you don’t have to worry about vertical clearance.
  6. Take the midpoint of the base curve (the red one) and shift it vertically by 1.5 units (or 1.5x your voxel dimension) to ensure it is not inside a filled voxel.
  7. Build a distance field from the translated mid point.
  8. For every other curve pull the start and end points, translate them up by 1.5 units (or 1.5x your voxel dimension) and get the path from the source of the distance field to the sample point.
  9. Query the length of the resulting paths - if the length to the end is less than the length to the start, your polycurve needs to be reversed.

As a bonus while you are at it you can also use this method to define primary and secondary roads by number of trips (build the path from each lot based on number of units/trips to build a heat map which you can use to size each segment of alignments), route utilities (since they are under the roads anyway) and even identify ideal locations for stuff like public transit or fire hydrants.