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This is something that's probably easy to do but I've never been able to figure it out. I'm trying to model an offramp for a road.  There is 30' of elevation change.  The ramp has a multi-radius curve in it.  I have composite curves for both sides of the ramp but they are only in 2D.  How do I make one end of the composite curves slope up 30' so I can sweep a shape along them and build the ramp?  The only thing I can figure out is make it a Nurbz curve and fake it but I'd like to figure out something more accurate.  thanks

temp.fmz

curve.jpg

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I could even go and distribute crossing segments and use the terrain tool.  That seems like more work than it needs to be.  All these tools it seems like there should be an easy way to do this.  

thanks for the reply!

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Posted (edited)

Do you just need a surface?

Probably not the most accurate way to do this, but here's how I would do it:

First, I rotated copies of the compound curves upward so the endpoints aligned to the predefined straight ends where 1 is 30ft higher.  Then I moved 1 endpoint on each curve so it attached to the predefined 30ft raised straight end and closes the shape:

image.thumb.png.52fb03b9808618d74f3a7522bcffcc0f.png

Then I tried to Derive a face from the new shape, but it doesn't work?  So I created a Cap minimal surface from the outline segments:

image.thumb.png.3c57660518cfdfca3fe5e120a9934780.png

I moved it 100ft north for this demonstration. 

Is this what you need?

offramp-jm2.fmz

Edited by Justin Montoya

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Thanks Justin.  For what I'm doing it doesn't need to be perfect.  That definitely works.  I run into this situation every so often so I thought I would throw it out and see if I was missing something obvious.  Doesn't sound like there is a specific way to accomplish this accurately.  

edit - hold on, I just figured it out.  The stair tool set to ramp.  Do one for each rail, pull off a spline and make surface.  A few more options in the stair tool and it would accomplish all of it.

thanks for all the comments!

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I use the ramp tool (stair) when I have a uniform width slope.  When the width or shape of the ramp is non uniform then I create a spline on the XY plane, move the control points up to their desired positions,  offset the spline for the inside of the curve, adjust the control points to where I need them,  Then form a nurbz plane between the two splines.  Now that I have my nurbs plane I can extend and add onto it pretty easily to complete my roadways.  The terrain tool works as well but it feels so antiquated.  Probably because it has been around for at least 25 years in its current state.

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"Probably because it has been around for at least 25 years in its current state"

Great point!  Anymore my work consists of fixing disastrous Revit models and building sites for those Revit models.  The single most beneficial tool that I could use is something to make sites easier. Get rid of the guessing game that is fixing imported topo lines!  Interpolate X feet beyond the generated site.  Live boolean.  Sculpting tools. A road/sidewalk tool that would fit the topography up to a constructed road. Curb generator.  Random terrain function.  Retaining wall generator..... now I'm just getting crazy!  But it's nice to dream.

 

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