Change a shape without starting from the beginning

unhandled

#1

Hello.
I’m wondering how to change a below shape:

  • from the start line linearly to the stop line
  • shrink the shape from 0 to -1mm respectively
    The rest of the shape must stay unchanged - just a nose must be more “aggresive”.

Would you recommend any ideas?

Thank you,
Codi.

image

image


(Pascal Golay) #2

Hi Codi - it looks like that surface is dense enough to just select control points and Scale1D back a little.

-Pascal


#3

Hi Pascal.
I’ve tried… with scale 2D, 1D and it doesn’t work as I thought.
The point is that scaling/shrinking should be from 0 at the start line to -1mm at the tip of shape.
As I did a hell of manual corrections to get final shape, I would like to avoid the same work from the begining (first shape was SurfaceFromNetwork and later manual corrections).
So I’m looking forward to any ideas to try.
Finally it should be shrinked similar to red line below from all directions.
Thank you,
Codi.

image


shape.3dm (112.7 KB)


(Pascal Golay) #4

Hi Codi - does this help? There are reference points 1mm apart that I snap to with Tab direction lock on the Scale1D.

-Pascal


#5

This is good riddle! The obvious, but time-consuming solution is to shrink every slice of the control points separately by different ratio. Pascal is not shrinking the cross-sections - he only makes the nose shorter, so he shrinks the distance between the cross-sections.


(Travis Serio) #6

Taper or CageEdit might be handy here as well.


#7

Exactly! I was typing the same sentence almost the same time.


#8

Hi.
I tried scale it similar to presented footage - the point is I want to preserve lenght and change diameters smoothly from 0 to -1 (more or less).

Tapper is a good hint, I hope it might be the way - I can’t only keep the shape with it.
It tends to flatten curved edges. Please have a look below.
I tried to play with parameters - honestly don’t underestand all of them fully, so maybe there is one which could help to maintain shape?

Finally I struggled with CageEdit. Results are promissing and again not all parametr are clear to me. One of them is falloff distance. By blind trials I see a difference but … I don’t get it.
What is falloff distance? And I’m sorry from below manual it is too hard to underestand to me :flushed:

Of course I read:
http://docs.mcneel.com/rhino/5/help/en-us/commands/taper.htm
http://docs.mcneel.com/rhino/5/help/en-us/commands/cageedit.htm

image


#9

This command is called Taper (not Tapper). Select control points only and set Infinite option to yes. (F10 turns the control points on. F11 turns them off.)


#10

Hi Adrew.

I’m doing like you mentioned and still get a strange shape.
I was trying differnt option from line 3 below and… got similar result :frowning:


image
image


#11

Apparently you want to accelerate the shrinkage at the tip of the nose (on the right side of your sketch). Taper cannot do that, but CageEdit can. If you want to try it out, make box-shaped cage that has rows of three control points in the axial direction. (Make box first using Box command, then adjust number of control points with Rebuild command or RebuildUV command.) Shrink the control points of the cage in two cross sections: at the tip of the nose and in the middle. (You can shrink the control points with the Gumball/Shift, or with Scale2D command, or with Scale command.)


#12

And why not extractisocurve - trim - and rebuild with curves just the part you want changed? You wouldn’t need any of this stuff.

Hint: if you use shrinktrimmedsrf + mergesrf afterwards it’s still gonna be a single surface…

Also if I may be the grinch: did you check your shape in front view (screenshot of isocurve extracts from your surface) >


#13

my 2 eurocents:
Cut along the line “start of shrinking”, then use blendsurface or sweep to construct the surface exactly as you need.
It’s just too much of a hassle to try to manipulate the control points.

cheers, Norbert


#14

Hello.
I’m still struggling with final shape…
I saw what Vladimir shown in the picture and… yeah, it looks like it looks :thinking:
Could you propose any ideas how to improve it?
Thank you,
Codi.