Control Point Control?

Next
 From:  OSTexo
8496.1 
Hello,

Is there a way to calculate and build offset curves and surfaces that retain the number and layout of the original curves or surfaces? For example, when I blend between two curves I have a controllable layout, but when I offset that curve I'm left with dozens of control points that make the offset curve impossible to modify as easily as the original curve. Without a PhD in mathematics is there a way to model this manually?
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  Michael Gibson
8496.2 In reply to 8496.1 
Hi OSTexo, it's not possible to have the same control point structure in a true offset curve, to have an accurate offset it goes through a fitting process.

Just offsetting the control points alone does not generate an actual offset curve, in some cases it might be close but also in many cases it's not close at all, see here for an example: http://moi3d.com/forum/index.php?webtag=MOI&msg=3838.23

You might try using the Rebuild command on the offset with a fairly loose tolerance like say 0.1 or 0.05, that should reduce control point density by a lot at the expense the accuracy of the offset.

- Michael
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  mkdm
8496.3 In reply to 8496.1 
Hi OSTexo.

Well... if I understand correctly, you're trying to do the same thing that I discussed some month ago with my thread
"Lightweight Modelling. A case study." (http://moi3d.com/forum/index.php?webtag=MOI&msg=8135.1)

Here I post now a complex and slow, but good solution to achieve one of that tasks, that is :
construct an offsetted control point curve in a lightweight way, to get almost the same topology of the source curve.

I hope that this material may be useful for someone.

A great think could be to write some sort of script that should do automatically all that manual steps.

Here's the video tutorial I created. It's 155 Mb so if you have a slow connection maybe it's better to download it first.

http://take.ms/qhYFO

And this is the script I wrote some time ago, ExtractCurvesControlPoints.js:
https://monosnap.com/file/qklpik3YOeWOVXMkHEpngtOIObPP0C
(it's based on one Max's script).

Place the .js file into the "C:\Program Files (x86)\MoI 3.0\commands" (for windows users).

Please, let me know what do you think about my tutorial.

See you.

- Marco (mkdm)
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  mkdm
8496.4 
P.S. regarding my previous post.

As I wrote also inside the video tutorial, that manual method is good ONLY if you don't care of accuracy of the resulting curve,
bit it's useful only if you want the resulting curve to have THE EXACT amount of control points of source curve.

See you.

- Marco (mkdm)
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  OSTexo
8496.5 
Hello Michael,

Thanks for the explanation, I appreciate it. Would it be possible to adjust the Bulge parameter in the Blend dialog by a snapping point in the work area instead of a slider? If that can be done would it be possible to extend that functionality to a factor and ratio basis? If the onscreen snap is possible an offset can be created to simply be used as a reference. I'm not too concerned about file size, more so about curve and surface complexity. It may be a great reverse engineering tool for imported curve sets.
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  bemfarmer
8496.6 
I noticed that the Blend white paper has a blue ring incorporated in the blend.
http://www.integrityware.com/AdvancedSurfacing/Blending.pdf
- Brian
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  BurrMan
8496.7 In reply to 8496.6 
"""""""I noticed that the Blend white paper has a blue ring incorporated in the blend."""""""""""""

A blend "scaling rail"... Actually, the paper mentions and "unlimited amount"....

Kindof like "loft", but incorporated into the edge blend. This could be a powerful addition.

I guess we'll have to wait till modeling enhancements are back on the table, then see if we still have integrityware or a new kernel also, etc.....
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  Mauro (M-DYNAMICS)
8496.8 
Something like a loft with G2 connection
If so,it open a whole new solutions...just think in car model sessions ;)
Thanks Bem and Burr-the professor-Manator ! :)
M
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  Michael Gibson
8496.9 In reply to 8496.5 
Hi OSTexo,

> Would it be possible to adjust the Bulge parameter in the Blend dialog by a snapping point in the work area instead of a slider?

It could be possible to do that in the future but it would require support in the C++ back end, it's not really feasible to do just through script editing of the current version.


> If that can be done would it be possible to extend that functionality to a factor and ratio basis?

Could you describe the factor and ratio method in some more detail?

- Michael
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  Michael Gibson
8496.10 In reply to 8496.6 
Hi Brian,

re:
> I noticed that the Blend white paper has a blue ring incorporated in the blend.

That's a blend mechanism in Solids++ that uses a "derivative field" concept. When I tested it I found it to be problematic, sorry I don't remember the specific details. So MoI's blend function is a custom one I wrote myself, it's not using that particular mechanism.

- Michael
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  bemfarmer
8496.11 In reply to 8496.10 
Cool, Michael.

I may have asked before, but is there some way to get the x,y,z value of the Normal Vector at point "p" on a NURBS face/surface?
The Normal could be at iso (u,v) intersection point. A line normal to a face can be manually found on screen...

(My current project is solid sweeps, but the math is very difficult, and scripting can only do so much by itself :-)

- Brian

EDITED: 1 Jul by BEMFARMER

  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  Michael Gibson
8496.12 In reply to 8496.11 
Hi Brian,

re:
> I may have asked before, but is there some way to get the x,y,z value of the Normal
> Vector at point "p" on a NURBS face/surface?

Sorry, right now there aren't any evaluator functions like that exposed to script. But it's definitely something that I want to add in to v4.

- Michael
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  OSTexo
8496.13 
Hello,

Factor and ratio are in the first minute of this video:

https://www.youtube.com/watch?v=3dODbVtwY-0

I suppose they are VSR terms, I'm guessing Ratio or Factor refers to Bulge in MoI?

VSR is a great toolset but is held back by the Rhino interface, I can imagine MoI can make similar features highly usable.
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  Michael Gibson
8496.14 In reply to 8496.13 
Hi OSTexo, thanks for the video link. Yes I think the Factor is the same thing as Bulge in MoI.

But I try pretty hard to avoid really complex UIs with 30 or 40 controls in them like they've got there. But dragging points in the view wouldn't clog things up in the same way so that would probably be feasible.

- Michael
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  OSTexo
8496.15 
Hello Michael,

I agree 1000% on the VSR interface, it's not very usable. I happen to think an in-view method would be vastly superior anyway since you could snap to other geometry.

You could get away with one more drop down in the Blend interface if you were able to specify continuity per side. Bulge could be specified in interface as well as Ratio, which is likely poor terminology from VSR since it means nothing to the average user. Ctrl and Shift functionality to change Bulge and Ratio (name changed) options per side with appropriate feedback to let the user know their state, but no need for additional interface elements in dialog. Icing on the cake would be being able to drag and snap the blend along the input curves and to create a curve off of an input surface at an angle, maybe snapping that in view to geometry. So one drop down and one dialog slider to get all that functionality sounds close with the only other consideration being a visual state helper.
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  OSTexo
8496.16 
Hello,

Here's a Blend dialog sample. Terminology, e.g. Ratio should be tweaked, but the structure is there. No need for sliders when the process is in view. Bulge and Ratio run in lockstep by default until key press or manual entry?

Attachments:

  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
 From:  OSTexo
8496.17 
Hello,

Or this:

Attachments:

  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged
 

Reply to All Reply to All