I am currently working on a Stream Restoration project and am really struggling to find a flexible solution for modelling natural river corridors.
My Landscape Architect has provided me with a set of 2d-Polylines representing the proposed river alignment as well as some embankment lines. (Spline.jpg)
My first attempt was to create a corridor with a cross-section consisting of some generic links targeting my polylines. Please see attachment (Corridor.jpg). Obviously it results in a total mess. So I tried splitting the corridor in multiple sub-corridors targeting different lines as suggested by Dana Probert in her class on Stream Restoration. (Corridor1.jpg) However, given the curvature of these lines, the corridor simply never works as expected.
Question #1: is there any way to create a ‘smart subassembly’ which would prevent those bowties? Ideally I’d like it to be able to connect to subsequent vertices of the targeted line. Maybe the subassembly composer is capable of doing such magic tricks?
Since the corridor approach didn’t work I tried adding the Polylines as breaklines to a surface without any other definition. To assign some elevation data I converted them to Feature Lines. The original 2d-Polylines have been set to Fit -> Quadratic though and Civil 3d just refuses to accept them as they are. So I’d go splineedit -> convert to spline and then Flatten to convert them to Polylines back again.
This way I can convert my Polylines to Feature Lines, assign elevations in the elevation editor and add them to an empty surface. After playing around with the mid-ordinate distance and interpolation values I end up with something usable but difficult to manage (Surface feature line.jpg). The Flatten command converts my beautiful splines to a set of interconnected lines and arcs, which aren’t that easy to control. And for all this effort the resulting surface isn’t as smooth as expected (Object viewer.jpg).
Question #2: is there a way to convert splines to feature lines, or better yet – add splines as breaklines to a surface and derive their elevation from a profile?
My current solution to this problem is converting the 2d-Polylines to splines, and then back to Polylines via Splineedit. This way I get a Polyline with tons of straight but short segments. I convert them to feature lines, assign elevations and add as breaklines to the surface definition. The resulting surface is super smooth. It just isn’t easy to modify because of the amount of vertices that have to be moved to do any adjustments.
Question #3: Do you know of any better ways to approach this subject? All of the methods I’ve tried would have worked perfectly with a simple corridor. It’s the curvature that renders them useless.
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I have not had great luck using corridors for existing watercourses mostly due to varying widths, deflections, etc between CL and the banks. They're great with proposed channels with parallel banks and well defined transitions. That being said I typically use flines because I have them to start with.
As per #2 you are doing it the way I do it. The Flatten command will convert splined plines to plines. Convert to fline and weed. Get rid of as many verticies as you can without changing the channel. This is important for your performance. Fewer points in the surface is less processing time. The flatten command will create a large amount of verticies to maintain the splines path. Assign the know elv's and chuck them into your surface.
C3D will not accept splined objects as breaklines nor will they be converted directly to flines.
Am I misunderstanding something. I believe that 2012 would use splines in a Surface.
Of did that work so poorly that they took it out of more recent releases?
I found Splines mentioned as breaklines in 2014 help.
Wow. I COMPLEEEEETELY missed that new feature and awsome post from that awsome blog.
Unfortunately I am still programmed to remove all splines from all work. Now I'll never go creating splines for channels as this is a huge pain trying to grip edit the spline to the real shots but if someone delivers 3dsplines it would be a decent time saver.
thanks for your suggestions - I tried splitting the corridor in multiple regions and letting the TIN triangulate between them but with the complexity of the splines I would just end up with 500 regions per corridor that would intersect anyway.
I have found a solution to corridor bow ties, that suggests using a marked point subassembly and creating a surface from point links.
http://www.youtube.com/watch?v=KnvmCRDl_MM (the interesting part starts around 6:00)
It would probably work but for that I'd need to have 7 baselines in one corridor: one center line, and 3 lines per each slope. Each of the baselines would be using a simple subassembly with only a markedpoint. Am I correct?
This is cumbersome to set up, but would allow me to derive the elevation information from design profiles and change the geometry of the corridor in a relatively simple way.
Regarding adding 3d-Splines as breaklines. My problem is that I only have 2d Splines and I want to be able to control the elevation in a profile view. With featurelines it is possible since I can project them into a profile view and grip edit them afterwards. Is there a way to do that with splines?
As I stated in my first post - I am looking for a flexible solution that would allow for easy and quick changes. We are in an early stage of the design process and need the model to respond to our needs.
@John: what I am dealing with now is the exact opposite of your experience. The existing channel is just a straight profile with a continuos cross-section, since we want the proposed one to meander and resemble nature as much as possible, we are running into the above problems.
this looks very clean and simple! May I ask how have you built this corridor? It seems you are using 3 baselines, but how do you target them?