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Claus  
#21 Posted : Tuesday, February 23, 2016 1:41:02 PM(UTC)
Claus

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Art,

when using your exact file and even recreating the ellipse and the curved surface with your dimensions I do actually get a problematic projected curve. So I converted the curve to control point spline which gave me a deformed area that I cut away and made several splits along the projected curve, then joined the remaining curves left and right to the cutaway part so resulting gap would be closed, then joined the rest. I attached the resulting file for your inspection. I can't really explain why your geometry result in a bad projected curve, more experiments might reveal the exact cause but in these cases I just try to work around.

Claus
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Guidecover fixed.sfx (58kb) downloaded 7 time(s).

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Art Smith  
#22 Posted : Tuesday, February 23, 2016 2:13:37 PM(UTC)
Art Smith

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Claus-

thanks, I appreciate your help! that said, I don't know where that leaves me. attempting to "fix" problematic geometry that isn't understood without your knowledge, expertise, and experience doesn't seem like an attractive solution............. yes, I can extend surfaces, avoid boundary intersections, and displace source curves BUT what happens the next time a discontinuous curve results in spite of the precautions?? at the end of the day, I need to get to a dependable brute force (think D-8 or D-9 Caterpillar) self sufficiency solution that takes longer and isn't clever, elegant, or inspired like the work done by people like you that do this full time for a living!! conceptual design, NOT production design or something to hang in a gallery!!

Art
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Claus  
#23 Posted : Tuesday, February 23, 2016 2:24:00 PM(UTC)
Claus

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Don't despair! I think the problem is strange, maybe Tim can understand the underlying problem but as mere mortals we have to work around it. The attached is another way to do it, I extruded your ellipse and split it with your surface. The result "projected" curve works with guide cover.

Claus

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easy way.jpg (50kb) downloaded 6 time(s).

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Tim Olson  
#24 Posted : Tuesday, February 23, 2016 5:24:29 PM(UTC)
Tim Olson

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Hi Art
I made a quick video showing how to create a surface from projected curves.

http://www.csi-concepts.com/Demo/videos/trimSurf.mp4

Some notes/observations:

--The projection of the single ellipse into multiple segments is because the ellipse projects to the exact edge of the surface. At that exact point,there is no curve definition so ACIS creates multiple curves. If these additional segments are troublesome, use the Surface Extend and select the face to extend all sides of the surface a small amount.

--Generally you will get a smoother surface by trimming to an existing surface then recreating a cover surface over a reference surface. For example in the industry I came from, you would generally over extend your surfaces, and trim back to the intersection. I'm not sure this applies to your example but perhaps it might help on another task.

--I didn't see a guide curve in the file,so I just created a cover surface in the video. It actually created a pretty smooth surface when I checked zebra stripes.

--In the video I show using the Surface Boolean Intersection command. I made some corrections in the code to make that work properly in 1187:)

Hope this helps!

Tim
Tim Olson
Vice President Software Development
IMSI Design/Encore
thanks 1 user thanked Tim Olson for this useful post.
gjames on 5/17/2016(UTC)
Art Smith  
#25 Posted : Tuesday, February 23, 2016 6:49:28 PM(UTC)
Art Smith

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Tim-

thanks! different techniques are always interesting. so at this point are you attributing all of my problems to a surface edge point(s) where ACIS chooses to return two (ie: not multiple) curve segments? ie: is it safe to tackle my real geometry or should I indulge in another learn-by-doing project ??

the lines on the curved surface in my application can be thought of in the same way a one looks at lines on a topographic map. I'm interested in the surface/shape/profile (with respect to the wind) of the mountain and not the lines of equal elevation change. as shown in the image posted above, the guide curve for the fault isolation file is shown in "cyan" with a radius of 7"

fascinating the surface "smoothness" is effected by boundary conditions to the extent it's good practice to "trim"...................

Art
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Art Smith  
#26 Posted : Wednesday, February 24, 2016 12:52:55 AM(UTC)
Art Smith

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Tim-

what constitutes a valid "guide curve"?? we may be beyond "gaps", but it doesn't feel very far...

Art
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Art Smith attached the following image(s):
guide curve constraints questions.jpg (63kb) downloaded 6 time(s).

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