Composing multiple arcs

[BLINK Design]

After carefully zooming into the intersections of the arcs and lines which occurred where the arcs end (in order to close the 2D shape), I discovered that arcs and lines cannot be composed, only lines and lines or lines and polys.

I overlapped the handles using the smart cursor with great precision and trust me, they DO NOT COMPOSE! If I convert the arcs to either lines of polygons, the enclosing endlines compose (close) but the remainder of the arc is broken into hundreds of small line segments that must be composed as well!

Attempting to close all these lines at once crashes the program and composing shorter segments of the lines (which used to be arcs) converts these short segments into individual polylines which once again cannot be composed!

The goal is to have one 2D object that can be extruded as a solid, including it's face and not just the edges.

See the image below.

[Pat Stanford]

I don't know about something as complicated as your scrollwork, but in VW2008, I can compose lines to arc and arcs to arcs just fine. You do have to be very careful that the end points are exactly coincident.

Not a fun solution, but something you might try is to use the arrow buttons to step to the end points on the arcs/lines and make sure that the actual values in the OIP match for both objects you are trying to connect. I have found that even with high zoom factors it is not always possible to line things up by eye or even by snap points. Snap points are great for first drawing things, but trying to extend/shorten arcs to meet by snaps if tough.

Or move one object away and then back sometimes results in it being composable.

Pat

[Ray Libby]

Try posting the file itself.

[RGyori]

Blink, in the spirit of covering all the bases, be sure you are not selecting the one interior triangular shape located in the lower center of your composition.

[BLINK Design]

Hello Pat, I am not using v. 2008 though was advised by the VW techs that upgrading to v 12.5.3 would do the trick. There was no difference. Hours have been spent thus far using the techniques you have suggested including selecting two adjacent objects and visually noting that the handles were precisely overlapped.

Maybe breaking the object up into smaller pieces and then using ADD?

Vectorworks?

[BLINK Design]

RGyori, the only time I selected the interior shape was after converting everything to lines and attempting to compose the whole thing. The program crashed after about 20 minutes! Normally only the desired lines are selected.

[Tom G.]

Make sure Snap to Grid is not enabled.

Sometimes crossing two curved lines, then using the trim tool, assures a perfect end-to-end match.

While I've never attempted to model such a complex shape, I have had success by drawing a closed polyline (composed of straight lines) over my template, then using the 2D Reshape tool at add curves and thus pull a straight line into an arc to match the template below. If you only have to close two ends to begin with, then so much the better.

Try Clip Surface or Subtract Solids to aid in creation of the circles and arcs.

If you convert your curve to a NURBS curve (even straight lines can be NURBS curves), there is a command called Rebuild NURBS which will allow you to remove OR add nodes thus making the reshape much easier. (I'm starting to get over my head with this last comment so if someone else can build on it, feel free.)

Edited March 12, 2008 by tguy

[BLINK Design]

tguy, excellent point. I will check the snap to grid although I have been using the smart cursur to identify end line correlations.

[Benson Shaw]

I'm in 12.5.3 and I can compose a small number of 2d lines to a small number of 2d arcs. It has trouble with large combos, though,

Often the Combine Tool (2 obj mode) works when the Compose Command fails. That's a one at a time deal, but might get your shape closed. Change color of the one you are building for easy visual check on whether the tool worked.

-B

[cbaarch]

given this task I would treat this object as a single polygon

to get the arcs you draw a large one first

then offset as required - once created clip the surface

when all done add surfaces

[MullinRJ]

Hi BLINK,

Interesting problem. Were you starting from a scan or winging it freehand? I took the liberty to copy your picture into a VW file and trace over it. Though you can get the arcs to line up in theory, I agree it is a difficult task with the stock tools at hand. If you would like to try a DEMO of Reshaper I think you will find this is an easy task, though still tedious. Ask and you shall receive.

Reshaper gives you the ability to anchor either endpoint while you edit an Arc's Sweep and/or Radius. If you draw an arc and one point is snapped to the previous object, you can edit the Arc repeatedly with Reshaper and Reshaper will leave that point fixed on the drawing so you will not have problems composing your 2D objects into a PolyLine.

I was able to compose 83 Arcs & 5 lines all at once. The file and a screen shot are attached.

Raymond

[sketcher]

MullinRJ, do you have a link to the RESHAPER program? I run into similar problem, tho not as complex. I am having trouble making simple "S" shapes.

[MullinRJ]

Hi sketcher,

Yes, the link is "siriussolutions DoT net" but change the "space DoT space" to a period "." and it should work. To try the demo, use the "info" email address on the website and send me the last 6 digits of your VW serial # and I'll email you the software and a DEMO KEY. The demo is free for 30 days.

Thanks,

Raymond

[Tom G.]

http://www.siriussolutions.net/

$50

[MullinRJ]

Well, so much for keeping the address away from the spam bots. I guess it doesn't really matter, but I'll know in a little while.

[Ray Libby]

tguy, it looks like Raymond was trying to keep his address away from the spambots by posting it as "siriussolutions DoT net".

[BLINK Design]

Hi BLINK,

Reshaper gives you the ability to anchor either endpoint while you edit an Arc's Sweep and/or Radius. If you draw an arc and one point is snapped to the previous object, you can edit the Arc repeatedly with Reshaper and Reshaper will leave that point fixed on the drawing so you will not have problems composing your 2D objects into a PolyLine.

I was able to compose 83 Arcs & 5 lines all at once. The file and a screen shot are attached.

Raymond

You traced the entire object! Awesome effort. I was not in a position to upload the file due to proprietary constraints. Yes, please send me the Reshaper as a test as I know this problem will arise again. I am wondering if Reshaper also helps with the other problems that I am posting below with the final model. Thanks!

[BLINK Design]

What worked, albeit clumsily, was the removal of all unnecessary handles and the conversion of any polylines into polygons. Polylines would not combine with lines!

A 2nd problem emerged though when I was creating the receptacles. Once an extrusion has been made, or a solid subtraction as is the case with this model, what object types can be manipulated cohesively from a corner rather than an entire extruded surface only? I have no idea how to drag the corner of the one object down to meet the corner of the other. (See the second image).

These objects are made up of hundred of little 3D polygons that describe the curve and each are flat on the top. To pull the corners of each facet down one by one is not a reasonable solution and it's not accurate. To plot the points in 3D space to loft them is exceptionally difficult because I need to construct the object first to know where the points are in space to create a smooth curve.

The reason this it's not level is that I used the solid subtraction method to slice off the top portion of the curves at an angle. The chords rise up towards the round ends for a distance of about 1" to accommodate the inner receptacle.

There are other program more suitable than Vectorworks for product design I realize though my request here is reasonable given that buildings include moldings and sculpture and furniture as well.

Thanks for all the input!

[Benson Shaw]

I can get the extrude to work, although my figure is nowhere near as elegant as yours. The inner spiral is made with the spiral tool with thickness. Then ungroup and split the end caps (delete the outer one) so spiral becomes two polylines. The deconstructed spirals and the other polylines and arcs for the nodes composed in one step. The extrude returned walls only on first try, which always means that there is an open facet at one of the corner points. I found it where a poly met one of the arc nodes. The final extrusion then returned solid and has a manageable number of control points. Receptacles can be extrudes which live inside the nodes. No solid addition needed. Do that inline hole last, on a copy poly, as a clip surface to the extrude poly. Once you clip, the polylines may get more vertices.

I am not quite getting the solid subtraction question. Does the extrude need to be modified so that the top is no longer parallel to the bottom in some places? A flare to the nodes? It might be better to model most of the shape as an extrude, then use nurbs and lofts to make separate solids for the special areas. They can touch the extrude or combine via solid addition.

But one way to moosh around an extrude is to convert it to NURBS then convert that to mesh. Or extract curves, edit them and loft the whole thing. Direct to mesh yields more vertices, which is a pain.

-B

[islandmon]

A simple ExtrudeAlongPath using a radiused profile will build each of the curves. Here's a quick example of the main curve. Additional curves can then be added to complete the final form:

[BLINK Design]

Establishing a centerline from an incomplete poly was the problem (this model is the prototype from which the product was to be constructed so the degree of error was extremely tight) as well the end condition flare out and up. Extrude along path for the end sections would have taken dozens of manual attempts to get it correct given that it has two uneven curves as sides and it's top was slightly inclined.

Thanks for the example....

[BLINK Design]

I am not quite getting the solid subtraction question. Does the extrude need to be modified so that the top is no longer parallel to the bottom in some places? A flare to the nodes? It might be better to model most of the shape as an extrude, then use nurbs and lofts to make separate solids for the special areas. They can touch the extrude or combine via solid addition.-B

Precisely! I am unpracticed with NURBS primarily because I struggle to figure out how to place 3D points precisely in space in order to create the planes in order to loft them. It seems a catch 22 and I seem to have a relative brain so once I get out there in space I feel a bit disoriented.

For the 'nearly correct' solution I extruded to the highest point and tilted a cube to subtract a solid at the proper incline but it did not meet the main curve evenly. See the image in the FINAL post.

Thanks for the thoughts...

[Tom G.]

Well, so much for keeping the address away from the spam bots. I guess it doesn't really matter, but I'll know in a little while.

Sorry to miss the message between the lines. And really sorry if the bots have gotten you on my account.

But how does one reconcile the need to sell a plugin with the requirement to keep one's website semi-secret? Having not seen a proviso (in your post or elsewhere) to not publish the addresses of commercial sites, I pass on loads of these all the time.

Is this always a bad idea?

Thanks

Edited March 17, 2008 by tguy

[MullinRJ]

No, not a bad idea and no offense taken. Silly me, I was being overly paranoid. Web crawlers are not avoidable so no harm has been done. I already get daily updates on ways to increase my manhood and places to buy name brand software for pennies on the dollar, and this month's special seems to be a run on luxury watches. At the moment I'm only getting a few a day, but last year it was dozens a day.

While you're here, wanna try some free software?

Raymond

[Tom G.]

As if to answer my questions, today's USA Today (Money, March 17) has a great article on the danger of spam bots.

Now back to our regular program.