Project Curves to Surface

Rhino Rhino for Windows
1

Hello there!

I am looking for some help with projectikng a group of curves (highlighted in yellow) to a spiral railing (red surface). I have tried numerous commands but none have been successful.

all suggestions are welcome!

Image.JPG791×766 51.4 KB

2

First of all, you need to be in the viewport where the projection will occur. As this command is governed by the construction-plane-grid, the perspective will not work – as its grid is (usually) on the floor. Try switching to the side view – or whichever view where the highlighted curves look correct.

Secondly, projecting curves can be tricky onto a curved surface. You will get some distortion as the surface is less perpendicular.

A trick I use is to rotate the curves (or railing) so that the curves are projected into the center of the railing. Then, any distortion at the top and bottom is equally shared and reduced.

Try that and report back… there are a few more ‘plans B / C / D’ I might try, but I’ll save them for later.

3

Another way to get the curves onto the curving surface is the Pull command which is viewpoint independent.

Do you want to wrap the curves onto the railing? If so that is different than using Project or Pull.

4

I was going to mention the pull command, so that can be a effective option.

The trickiest one (and most accurate) would be the flow along surface. One ‘hack-trick’ you can use is to do the surface flow on your railing BEFORE a trim. With a flow, you have three elements:

  1. The curves
  2. A reference surface / plane (right on top of the curves)
  3. A target surface, which is your railing. Try doing it when the railing is simpler, prior to a trim. This would be an arc extruded upwards. Do the flow. Now, trim that curved surface to get rid of the un-wanted top and bottom sections.
5

Thanks to both Schultz and David for the suggestions. Both worked but the front view projection worked slightly better. After testing the amount of skew the projection caused, I pre-skewed the curves in the opposite direction to get a more accurate projection.

Thanks!

AG

6

Here is a method to get a true orientation. I’m assuming that you’re happy with using a portion of the pattern and trimming the remaining away.

From the top view - looking down at the stairs, flatten out the rail profile. Use ‘ProjectToCPlane’ to project one of the rail surface edges to the ground plane.

Use ‘Orient To Curve’ in the Transform menu to bend the flat pattern to your flattened rail curve. Now your pattern should be wrapped around the rail surface. You may need to shift the wrapped pattern up or down to get the desired position.

Then you can trim the excess. You’ll have a non distorted wrapped pattern.

Hope this helps - if not send me the file.

Sach

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