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Struggling with ruled surface


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#1 bbuxton

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Posted 07 August 2017 - 11:45 PM

Hello 

 

I am trying to create a ruled surface between two non planar sets of curves.

I have tried numerous methods but no success so far.

* tried using the imprint tool to project planar curves onto nurbs surface

> one curve managed to imprint the rest failed.

* Tried extruding the curves and using line of intersection to get the profiles

>This worked but the curves are very bad and cannot create a ruled surface

>Also tried boolean subtraction and deleting the unwanted faces

* tried sweeping a straight line segment along the lines of intersection

>This doesn't work either

 

My suspicion is that the curves are not good. I have tried creating the curves in FormZ and Illustrator and the problems are the same.

Attached is the file with curves drawn in formZ if anyone would like to have a look.

I don't work with curves or nurbs in formZ very often so have run aground quickly with this one.

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  • 3d scan render.jpg

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#2 Tech

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Posted 08 August 2017 - 11:42 AM

bbuxton, 

 

can you please elaborate on what exactly you're trying to do?  we were able to difference one geometry from the other after ungrouping them.  

 

to create the relief, we extruded the letters until they intersected the large object, then offset the outline of the profile of the large object, used this line to slice the extruded letters, and then you can union the letters into the large object.

 

is that what you are trying to do?

 

 

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  • Screen Shot 2017-08-08 at 12.39.14 PM.jpg
  • Screen Shot 2017-08-08 at 12.39.36 PM.jpg
  • Screen Shot 2017-08-08 at 12.40.07 PM.jpg


#3 Bartjuan

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Posted 08 August 2017 - 12:17 PM

HI Bbuxton

 

You suspicion is correct. the geometry has overlapping parts. Especially the "A". The top right point of the front face is a loop. As is the bottom inside corner of the lower opening.

Also, the two faces of each letter seem to have different numbers of points and in different positions around the letter, this will effect the loft.

 

I will see if I can put some more time into it. 

BTW, I was having some success with extruding the backfaces, converting to mesh and them using the Draft Angle tool but I was again having problems with overlapping geometry

 

Bart



#4 bbuxton

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Posted 08 August 2017 - 06:49 PM

bbuxton, 

 

can you please elaborate on what exactly you're trying to do?  we were able to difference one geometry from the other after ungrouping them.  

 

to create the relief, we extruded the letters until they intersected the large object, then offset the outline of the profile of the large object, used this line to slice the extruded letters, and then you can union the letters into the large object.

 

is that what you are trying to do?

 

Thank you for looking at this. Your example the letters are the wrong shape. With a simple form such as a square I found the best method was to generate lines of intersection for the inner and outer profiles and the background and foreground meshes. Then generate a ruled surface with caps. This generates the correct shape. I think what I really need is some tips on how to clean up the curves and find the errors.

 

I expected the inner curves to have the errors as these are inset from the outer curves using the offset outlines tool.

However it is the outer curves that are causing the most trouble especially when used to create line of intersection with the background molding. I have no idea how to prevent this operation from forming bad geometry or to resample the curves to have matching and consistent points.

 

This is just a small section of the Pugin inscription that I am trying to prepare for 3D print or cnc fabrication.

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  • pugin scan ortho.jpg

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#5 Bartjuan

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Posted 09 August 2017 - 10:48 AM

BBUXTON

 

these curves look a lot cleaner,

I was able to rule these with no problem,

 

Bart

Attached Thumbnails

  • pugin MAN Solids.jpg

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Edited by Bartjuan, 09 August 2017 - 10:54 AM.


#6 bbuxton

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Posted 09 August 2017 - 09:30 PM

BBUXTON

 

these curves look a lot cleaner,

I was able to rule these with no problem,

 

Bart

 

Thank you Bartjuan. Yes this bit works well here too.

Things go astray after projecting the curves to the two molding profiles.

When using imprint, line of intersection or extending either side of the ruled surface then boolean the molding profiles, the result is messed up curves or surfaces. 

To get this to work I must either fix the curves so that they will produce a clean ruled surface or work flat and try and get the text to follow the molding profiles using deformers.



#7 Bartjuan

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Posted 10 August 2017 - 11:12 AM

AH, I see, 

You want to project the letter backface ONTO the curved surface of the crown.

Then project the letter front face on to the curved surface of the "cutter" and then loft (rule) between the two to get, curved and beveled letters.

Is that right?

 

How about applying a bend to the extruded shapes instead?

 

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  • Bend 01.jpg

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#8 bbuxton

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Posted 17 August 2017 - 09:15 PM

AH, I see, 

You want to project the letter backface ONTO the curved surface of the crown.

Then project the letter front face on to the curved surface of the "cutter" and then loft (rule) between the two to get, curved and beveled letters.

Is that right?

 

How about applying a bend to the extruded shapes instead?

 

 

Hi Bartjuan

 

Thank you for this. Your file is much closer to what I am trying to achieve.

For lofting between lines of intersection it is possible to get it to work when the letters are a bit smaller.

I think because in formZ the line of intersection creates a surface with 3 'faces' (I think maybe because the top is concave the middle convex and the bottom ever so slightly concave too) the loft is too complex and fails. . 

 

My attempt the draft angle is too shallow resulting in the top and bottom of the letters being too thin where they meet the background profile and too thick where they meet the foreground guide surface.

 

I'm hoping that ZWeb will chime in about lofting between lines of intersection that have been generated by a complex surface with some advice on how to make this easier. This is a bit too technical for me. 

For now I will try to recreate this with a subdivision surface which is easier to manipulate and see if the results are good enough to get an accurate 3D print. 

Attached Thumbnails

  • pugin acis solid render.jpg
  • pugin MAN Solids.jpg

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#9 Tech

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Posted 24 August 2017 - 09:05 AM

 

I'm hoping that ZWeb will chime in about lofting between lines of intersection that have been generated by a complex surface with some advice on how to make this easier. This is a bit too technical for me. 

For now I will try to recreate this with a subdivision surface which is easier to manipulate and see if the results are good enough to get an accurate 3D print. 

 

 

Sorry we are having trouble understanding what you mean by "lofting between lines of intersection... generated by a complex surface...."

 

Are you talking about the Nurbs by Cross Sections tool, or the Nurbs by UV Curves tool?  

 

Can you please clarify and provide a simple example?  



#10 bbuxton

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Posted 27 August 2017 - 07:34 AM

Sorry we are having trouble understanding what you mean by "lofting between lines of intersection... generated by a complex surface...."

 

Are you talking about the Nurbs by Cross Sections tool, or the Nurbs by UV Curves tool?  

 

Can you please clarify and provide a simple example?  

 

Each letter has two outlines an inner out line and an outer one. The background geometry is an extruded profile the foreground geometry is a simpler extruded profile. Ideally the outermost letter outlines to be projected onto the background geometry and the inner outlines if the letter should be project onto the foreground geometry. This is to match the orthographic reference that the letter outlines are drawn from. I then have to loft between the two sets of projected outlines. As you know there are lots of ways to do this in FormZ but I have struggled to keep clean outlines that loft well.






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