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splines - twist - surfaces (#3983)
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la mouche  
#1 Posted : Tuesday, September 27, 2011 6:02:57 AM(UTC)
la mouche

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Hello,

What is the best method to create a solid or surface with this splines, please?

after 2 days of work .... I still can not

Thanks

http://screencast.com/t/l7a3IIP4GqZu

Antoine
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rockyroad_us  
#2 Posted : Tuesday, September 27, 2011 7:15:25 AM(UTC)
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I think you need the same number of points.
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jlm  
#3 Posted : Tuesday, September 27, 2011 10:24:46 AM(UTC)
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Originally Posted by: la mouche Go to Quoted Post
Hello,

What is the best method to create a solid or surface with this splines, please?


Hi Antoine,

Did you try "change object type" for the splines ?

I think "Control points splines" are better than "interpolate" to build surfaces.

Maybe...

But Rockyroad is right, when the number of points is different, it's never perfect.

On this type of construction, I would build new splines with less points on top, and add a few guides in the other direction...


Good luck,

JL
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lgrijalva  
#4 Posted : Tuesday, September 27, 2011 11:57:27 AM(UTC)
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Originally Posted by: rockyroad_us Go to Quoted Post
I think you need the same number of points.


Several times i had been tried working with splines with the same, (i assume for Antoine's screen cast that he offset the first one made with lets say 10 control points and ended with offsets with a huge amount of points).

My question, if you have an original one with 8 points, why the offset doesn't "offset" with the same amount of them?, so it is hard to draw and control this patterns of splines with the same point count unless you draw one by one, that IMO should be done by simple offsetting the original and then modify the resulted ones if you need it, (most of the case you nee to modify on or two to get the desired pattern.)

Luis G.
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la mouche  
#5 Posted : Wednesday, September 28, 2011 1:59:45 AM(UTC)
la mouche

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hello and thanks for your interrest :)

Quote:
My question, if you have an original one with 8 points, why the offset doesn't "offset" with the same amount of them?, so it is hard to draw and control this patterns of splines with the same point count unless you draw one by one, that IMO should be done by simple offsetting the original and then modify the resulted ones if you need it, (most of the case you nee to modify on or two to get the desired pattern.)


[COLOR="red"]yes it is a serious limitation[/COLOR]

----------------------------------


Well ...

I have a lot of points, because I had to redraw my spline, spline with another spline reference.
I think this is a normal process.

The problem: Shark does not reach the last point (end) of the spline with the first point (start) ...

[COLOR="Lime"]"TIPS" created starting with the spline on the starting point of the spline reference[/COLOR]

http://screencast.com/t/N2EYp43yJ8HL

1 - why can not Shark snap the first point of the spline with the last?

----------------------------------

So, I created a little spline to close the spline at all.
Then: I linked the two splines together with the [COLOR="Red"]"join curve"[/COLOR]
result: lots and lots of point.

2 - Tim? please! Why Shark adds a lot of points [COLOR="red"]with this tool?[/COLOR]

----------------------------------

Thanks.
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la mouche  
#6 Posted : Wednesday, September 28, 2011 2:17:20 AM(UTC)
la mouche

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an unsatisfactory solution ... to draw the surface

http://screencast.com/t/m3cUprRZEo

Antoine
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jol  
#7 Posted : Wednesday, September 28, 2011 4:09:11 AM(UTC)
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Some good real-world questions in this tread Tim

If you really want to make these tools easier to use - it's these workflow bottlenecks we all encounter that you need to address

I'm sure these problems don't require massive amounts of time to solve - but removing these stumbling blocks would make life so much easier

such as

a tool to give you an offset with the same number of points (with I guess a deviation from true offset feedback)

such as

a profile manager that gives you real and useful information of where the gaps / overlaps are .... actually

such as

snapping the end of a spline to the start - still no explanation of this in 10 years

such as

modify slope tool always needing to be flipped - when tangenting a spline into a surface or solid. Can you at least add the option key to flip this over - and save you from always swapping tools again ?

such as ...

i'm sure there are loads more
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la mouche  
#8 Posted : Wednesday, September 28, 2011 4:54:55 AM(UTC)
la mouche

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Jol, thank you for your support.

Antoine
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ZeroLengthCurve  
#9 Posted : Wednesday, September 28, 2011 12:42:36 PM(UTC)
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Antoine,


Did your curves come from an external tool, or did you originate them in Shark?

Story of my problem with my externally-originated curves.

I experience something similar when I import my models from Delftship and Free!ship. At first, I wasn't sure of the problem's source. Could it be DS/FS? Could it be ViaCAD? In my case, I think it is my hand and eye, and my own improper use of the curvature plot facilities in DS and FS. DS has an auto-fairing feature, which is neat. FS does not have it. I needed to clean up some linework and was forced to export my model to DS (at some emotional expense since sending the files between the two apps involves some inexplicable reordering of layers, and there is no user-definable layer field which can be used to numerically force a custom sort).

But, when I made much use of the curvature plot tool, I found I maybe 20 curves which had curvature plots going off into infinity. Importing such lines into VCP as DXF 3D polylines had some impact, but out of over 700+, only 10 (near each other) caused me great grief. That grief was that I could not properly do 1-rail sweeps along those curves, and had to break up those curves and then do the sweeps. In some cases, i had to rebuild the curves in VCP. Where possible, I could flip some thicknesses but was uncomfortable with that as a way to get the surface to work.
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la mouche  
#10 Posted : Thursday, September 29, 2011 8:55:12 AM(UTC)
la mouche

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splines from SharkFX.
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Tim Olson  
#11 Posted : Friday, September 30, 2011 3:10:18 PM(UTC)
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>>What is the best method to create a solid or surface with this splines, please?

Did you try changing any of the Skin attributes?
--minimize twist
--arc length v parameterization
--arc length u parameterization
--alignment

The number of control points should not make a difference. It would be shape complexity and parameterization between the curves that would drive twisting.

Some images from the guys at Dassault/Spatial regarding this options.

http://doc.spatial.com/index.ph...Surface_Parameterization

http://doc.spatial.com/index.ph...ofting_Options/Alignment


Tim
Tim Olson
IMSI Design/Encore
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la mouche  
#12 Posted : Sunday, October 2, 2011 2:38:09 AM(UTC)
la mouche

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hello Tim,

thank you for your answer.

there is still a question:

Quote:
1 - why can not Shark snap the first point of the spline with the last?


Thanks.

Antoine
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jol  
#13 Posted : Sunday, October 2, 2011 4:10:06 AM(UTC)
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Antoine, if Tim answers / fixes this, I will eat all my roof tiles !
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blowlamp  
#14 Posted : Sunday, October 2, 2011 4:28:13 AM(UTC)
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Can someone explain what they mean about this, because I thought they already did snap first to last - unless you mean that the ends aren't made tangent if you subsequently try to join them by editing the line?

Hope the above makes sense :D

Martin.


***Edit: OK My bad. I now see that they don't snap (for some reason I thought it looked like they did?!?). So Tim, why don't they snap (hehehe)?
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blowlamp  
#15 Posted : Sunday, October 2, 2011 5:06:52 AM(UTC)
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The work-around is to drop a Point object on one end or the other and use that as your snap location for the opposite end of the curve.


Martin.
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jol  
#16 Posted : Sunday, October 2, 2011 7:17:06 AM(UTC)
jol

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Thanks Martin - appreciate the input, but we know the workaround ... that wasn't the request

The request is to fix the problem - so that people who are learning don't need to discover the workaround

Fixing stuff like this vastly improves workflow - and needs sorting first before the introduction of new tools - bringing their own workflow issues

There needs to be a limit to how long questions like this can be ignored - I count 10 years on this one

That's how I know my roof tiles are quite safe !
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la mouche  
#17 Posted : Sunday, October 2, 2011 10:17:21 AM(UTC)
la mouche

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mmhhh, watch.. more... my demo please .....

when the spline is only the latter is connected properly with the first.

This is when I use a spline reference (below) that it does not work


Antoine
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Tim Olson  
#18 Posted : Sunday, October 2, 2011 4:42:31 PM(UTC)
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>>My question, if you have an original one with 8 points, why the offset >>doesn't "offset" with the same amount of them?

Dassault/ACIS uses a precision algorithm for offsetting where everywhere between the points it must meet the definition of the offset (not just at the points). For example, offsetting an ellipse is not another ellipse.


Tim
Tim Olson
IMSI Design/Encore
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blowlamp  
#19 Posted : Sunday, October 2, 2011 5:28:10 PM(UTC)
blowlamp

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I'm not arguing against the idea, but what other software does allow the ends to be edited to snap together?

None of the other drawing programs that I have seem to let me do this, such as Solid Edge 2D Drafting, Dolphin CAD and Inkscape etc - although I'm no expert in any of them, so I could be missing how to do it.

Martin.
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Tem  
#20 Posted : Sunday, October 2, 2011 9:15:41 PM(UTC)
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Maybe there is a way to loft through all of the contours and close the loft?
Possibly do each side/depth, then boolean/trim and round/fillet between?
Kinda wonky, but maybe it is a possible approach? I know that I had tried a similar form years ago with an older version of Rhino, but found that surface point editing was the quickest approach.
Good luck!
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