Trouble creating a curved ramp

[pippawilde]

Hi all,

Trying to create a curved ramp. The ramp shape, in plan view, is a compound curve.

I've tried doing a loft surface--I've drawn basically a start and end profile--just 5' long lines, converted to nurbs curves, one at +5'-0", one at 0'-0 1/4".

If I draw a nurbs curve as the rail object that is an offset of either of the outside curves, then when I loft it doesn't exactly follow the outside curve shapes.

However if I use two rails, then I can only select one profile, which means it doesn't ramp, but just creates a flat surface.

With either method, it only creates the top surface of the ramp, not a solid object. Help!! File attached.

Thanks!

[Benson Shaw]

Hi, Pippa - Here is one approach. If you know more about the height of the stations, you can refine the shape. I duplicated your DL 1 and drew some new stuff. I traced your orig curves, with cubic spline, but you could use your originals instead:

Draw your ramp center line as a 2d plan view object, or convert your existing CL from NURBS to 2d Poly. Draw a vertical line L= width of ramp (assumes constant ramp width. 5' in my example). Select the line and center curve, and Duplicate Along a Path with curve as path. Number of dupes = 11. Choose the Tangent to path option, no initial offset.

Result is a series of 11 lines evenly spaced and perpendicular to the curve. While they are selected Dupe in Place, and Modify>Convert>Convert to 3d Polys. Result is a group. Change the line color so you can find them later (Red in my example). Ungroup, or enter the group, and select each one in turn. Raise the z value. Top one is 5', next is 4.5', next is 4', and so on in 6" increments.

When all z values are changed, use the flyover tool to some oblique view where you can see the endpoints of the ascending polys. Use the NURBS Curve tool to draw 2 NURBS curves along the endpoints. Now Loft the two NURBS - simple loft, not a rail or bi-rail - check the Keep Curves option. Render the sample layer to see ramp in lovely blue.

Result is a NURBS surface which rises to 5' and is parallel to ground plane at location of each 3d poly. Refine length & angle of polys or NURBS as needed and loft again.

The side surfaces of the ramp can be generated by lofting from ramp edge NURBS to a NURBS on the ground plane.

There are some other ways, but the curves you started with have too many vertices for easy manipulation.

Post back with what you come up with.

-B

[michaelk]

Benson

Nice workflow. You could also create all the lines, move the last one up to 5', then distribute / spacing to get the correct z values. It saves on having to do the math!

To answer the question about getting a solid rather than a surface, use the shell tool in the 3D toolset. Then subtract solid if you need to make the top edge vertical and the bottom edge horizontal.

hth

mk

[Benson Shaw]

Right, Michael. Good tip about z distribution. If tons of increments are used, instead of 11, that would really take out the tedium. My ramp starts and ends kind of abruptly, so one could also drag the z heights in side view to get better transitions. Prior knowledge of rise at each station would really help.

Shell Tool is a great tip, too! I tried your suggestion. It does generate a solid from the ramp, but the sides do not appear to be consistently vertical - if that's important. Shell must be created normal to the ramp surface, rather than projecting vertically from ramp surface to ground plane.

-B

Edited March 21, 2011 by Benson Shaw

[michaelk]

No, the sides will not be vertical. They will be normal to the nurbs surface.

You would have to trim it or subtract / intersect solids to get a vertical face.

[Benson Shaw]

Or loft to a NURBS on the ground plane. Use ruled option and loft from ramp edge down to ground, over to other ground NURBS, up to other ramp edge. All in one go.

-B

[MattG]

Pat Stanford helped me out with a project I was working on that had a similar situation. He made a video that helped.

Here is a link

http://www.vectortasks.com/Movies/files/Curved_Ramp.mov

[pippawilde]

ALL of these are fantastic suggestions. I have my curved ramps! Thank you all!

[mmurphy]

ALL of these are fantastic suggestions. I have my curved ramps! Thank you all!

I second this sentiment! Thanks.

[VincentCuclair]

Problem is that theoretically speaking a 'real' curved ramp geometry is not possible......I think I solved this once by using the stair tool with very small tread heights .....looked alright in 3D and acceptable in 2D......

Edited June 19, 2012 by Vincent C

[Simon Allan]

Thanks for the video, it was very helpful.

I am now try to create a ramp that has an increasing thickness from the end to the start and I just can't figure it out.

I have included the wireframe of what I want so hopefully someone can help.

I have drawn it as per the video above but have duplicated the top NURBS curves and placed them at floor level. I just can't figure out how to use the loft command to achieve the desired result.

[mike m oz]

Simon, the easiest way to do the ramp is to use a curved wall. Moving the 'wall top handles' produces a nice smooth rise in between.

[VincentCuclair]

Good one Mike!

[Simon Allan]

Thanks Mike...worked a treat and so much faster too.