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Tangent cover (#2333)
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Steve.M  
#1 Posted : Friday, May 22, 2009 11:50:39 AM(UTC)
Steve.M

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When creating a Tangent cover from 4 sides that are equal, then I would of expected the bulge to be central, but is not (see pic)

When changing the bulge value, the bulge shifts position.



- Steve
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Steve.M  
#2 Posted : Saturday, May 23, 2009 6:32:41 AM(UTC)
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I thought the problem may have been due to my using straight sides, but even with curved sides it still does not look right.
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unique  
#3 Posted : Saturday, May 23, 2009 2:20:39 PM(UTC)
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Originally Posted by: Steve.M Go to Quoted Post
When creating a Tangent cover from 4 sides that are equal, then I would of expected the bulge to be central, but is not (see pic)

When changing the bulge value, the bulge shifts position.



- Steve


Yip....I had my troubles too and in the end I gave up with VC for surfacing and returned to Rhino :( it just works!!

Tim - Can you show us if this is possible in VC or what workaround to use ?
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jol  
#4 Posted : Saturday, May 23, 2009 3:50:44 PM(UTC)
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you need the tangent cover surface tool !?
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jol  
#5 Posted : Saturday, May 23, 2009 3:55:14 PM(UTC)
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agree - it does seem silly that continuity is not also an option within the normal cover surf tool
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Steve.M  
#6 Posted : Sunday, May 24, 2009 6:30:53 AM(UTC)
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Originally Posted by: unique Go to Quoted Post
Yip....I had my troubles too and in the end I gave up with VC for surfacing and returned to Rhino
I can certainly understand. I will say that if I had purchased VC for work/production then I would of removed it some time go. It does make me wonder what others are using this product for, and why these problems are simply ignored by Vendor and users attempt endless workarounds.
Originally Posted by: unique Go to Quoted Post

Tim - Can you show us if this is possible in VC
I think this thread will be another IbT


- Steve
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Steve.M  
#7 Posted : Sunday, May 24, 2009 6:46:20 AM(UTC)
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Originally Posted by: jol Go to Quoted Post
you need the tangent cover surface tool !?


Are you serious?

I would like the tools I upgraded for to be more than just icons on the screen.


- Steve
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jol  
#8 Posted : Sunday, May 24, 2009 11:57:05 AM(UTC)
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I just tried again and you're quite right - it seems slightly lop-sided if I use the standard tool .. & it shouldn't !

However, if I use the tangent-cover-with-guide and put a point in the middle for the surface to pass thru (act as guide) - it "seems" good .. but you're very welcome to prove me wrong

That all said - a one-click-cover-with-tangency should be easy-peasy
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jol  
#9 Posted : Sunday, May 24, 2009 12:06:59 PM(UTC)
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Tim, sort your bulges out

A. for lop-sided-ness .. I find even with a guide, adding extra bulge means I'm 'dressing to the left'

B. for range .. why does this tool use a bulge factor range of 1 to 0 .. 0 being lots and 1 being little ?

FYI .. The deform tool has a default value of 500 and you often need 10000 to get a good result (.. and a higher number gives more bulge)

You need to audit all these tool and pick a reasonable scale .. say 1 incrementing to 10 .. and stick with it !

This kind of stuff should be behind us
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Steve.M  
#10 Posted : Sunday, May 24, 2009 12:25:50 PM(UTC)
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Originally Posted by: jol Go to Quoted Post
However, if I use the tangent-cover-with-guide and put a point in the middle for the surface to pass thru (act as guide) - it "seems" good .. but you're very welcome to prove me wrong


I dont have Shark to create that surface. Can you post the surface and I will check it in another application. I know that currently points do not keep tangency.

I currently see no point in my upgrading to Shark to obtain tangent cover with guides as the standard tangent cover should give more expected results in the example I posted. Also: there are far too many problems with other base functions to make upgrade.
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Tim Olson  
#11 Posted : Friday, May 29, 2009 10:51:39 PM(UTC)
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Steve,

Can you try a bulge factor of zero?

A lower bulge factor will represent the initial first derivatives of the referenced surfaces. A non zero bulge factor will use a Spatial algorithm attempting to minimize energy across the surface. I'm not sure why, but in those surfaces you provided, that resulting algorithm is not symmetrical. I'll need to send that part to Spatial for an explanation.


Tim
Tim Olson
IMSI Design/Encore
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dudko  
#12 Posted : Saturday, May 30, 2009 9:00:40 AM(UTC)
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Originally Posted by: Tim Olson Go to Quoted Post
Steve,

Can you try a bulge factor of zero?

A lower bulge factor will represent the initial first derivatives of the referenced surfaces. A non zero bulge factor will use a Spatial algorithm attempting to minimize energy across the surface. I'm not sure why, but in those surfaces you provided, that resulting algorithm is not symmetrical. I'll need to send that part to Spatial for an explanation.


Tim

Hi Tim
Bulge factor of zero is the same, not correct for CAD
Regards Ed
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jol  
#13 Posted : Saturday, May 30, 2009 9:40:36 AM(UTC)
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Good work Ed !

Tim - do you have enuf examples of this lopp-sidedness to get this off to Spatial ?
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Steve.M  
#14 Posted : Saturday, May 30, 2009 10:42:22 AM(UTC)
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Originally Posted by: Tim Olson Go to Quoted Post
Steve,

Can you try a bulge factor of zero?

I did try that but still not correct.

I see dudko had a look, and actually got a better result than my checks, so would also say the tool is unpredictable.

- Steve
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dudko  
#15 Posted : Saturday, May 30, 2009 12:50:52 PM(UTC)
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Originally Posted by: Steve.M Go to Quoted Post
I did try that but still not correct.

I see dudko had a look, and actually got a better result than my checks

- Steve

@Steve @Jol, that was tested in sharkFX build 835, in VC6 build 833 is extremely bad. Result in SharkFX with this tool, i see tolerance +/-0,1 in VC6 i have tolerance +/-1.0 max. 0.1 (very inaccurate)
Regards Ed
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Tim Olson  
#16 Posted : Saturday, May 30, 2009 4:11:47 PM(UTC)
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>>Tim - do you have enuf examples of this lopp-sidedness to get this off to >>Spatial

Yes, will send off to Spatial to see what they say. I suspect they will classify it as an enhancement request as it does appear to make a valid G1 surface but we're asking for alternative blending thereafter.

Tim
Tim Olson
IMSI Design/Encore
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Steve.M  
#17 Posted : Sunday, May 31, 2009 12:24:57 AM(UTC)
Steve.M

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Originally Posted by: Tim Olson Go to Quoted Post
A lower bulge factor will represent the initial first derivatives of the referenced surfaces. A non zero bulge factor will use a Spatial algorithm attempting to minimize energy across the surface. I'm not sure why, but in those surfaces you provided, that resulting algorithm is not symmetrical. I'll need to send that part to Spatial for an explanation.




Tim,

But as put forward, the initial zero bulge is incorrect. If Spatial is then calculating from that, then of course it will be incorrect and actually increase the problem, as it appears to be doing.


- Steve
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