Sculptured solid in 2011

[JHEarcht]

VW2011 Designer on Windows XP.

In the past, VW 3D was too slow and clunky for my simple modeling needs, and my old computer. So I've been using SketchUp mostly, for preliminary surface-only sketching. I have created a 3D model in SketchUp, sculpted from a solid extrude. But I ran into some limitations with non-orthogonal geometry and with lofted faces. The first image below is a view of the model, which has artifact ripples in the compound curved skin.

Therefore I decided to try the same model in VW2011. I was pleasantly surprised at how quickly and smoothly the 3D functions work in 2011, on my 6 year old machine. I push/pulled some 2D outlines thru a rectangular extrude to carve it into the approximate shape desired. However, I have run into a cul-de-sac. I don't know how to draw or project a guide line onto a curved surface so I can remove all except the edge. So I made another rectangular extrude and sectioned the model along the "knife edge" to remove one side. But I got a message : "you tried to create a solid object that cannot be computed". The result is shown in the second image.

The third image is noted to show the intended knife edge after one side of the model was subtracted. For now the other side remains to be cut away later. After both sides are removed, leaving only a plane along the "knife edge", the plan is to loft a surface between 3 curved lines. Again, I'm having difficulty working with non-orthogonal faces.

Any suggestions to complete the sculpting process will be appreciated. Thanks.

PS---After describing the problem, I think I know what to do. But I'll still like to hear your suggestions.

[img:left]http://home.mindspring.com/~gnomon/SU%20model%20front.JPG[/img]

[img:left]http://home.mindspring.com/~gnomon/VW%20Sectioned%20Solid.JPG[/img]

[img:left]http://home.mindspring.com/~gnomon/VW%20model%20front_noted.JPG[/img]

Edited December 20, 2010 by JHEarcht

[CipesDesign]

I am by no means an expert in these sorts of complex shapes, however I do have a thought: have you considered building the shape from its (smaller and simpler) component shapes, then Adding (instead of subtracting) the solids together (or even just grouping)??

[JHEarcht]

Normally I would build a model from walls, floors, roofs, etc. But this is not an inhabitable building, it's just a monumental sculpture. Also, most of the edges and surfaces are irregular compound curves. So I was following the same procedure that had worked in SU : carving away parts of a rectangular extrude by pushing 2D outlines thru the block.

Anyway, in the first post, I was barking up the wrong tree. So I have answered my own question. But now I need to figure out how to select the non-coplanar outlines of the flat (but not orthogonal) side surfaces, and then delete the face.

After composing the multiple straight and curved lines, I plan to loft, or drape, or bubble, or skin a new compound-curved surface onto the outline. I have never done that in VW. so I'll have to find out by trial & error how to proceed.

Below is a shot of the empty outline in SketchUp, before skinning. In this view it may not be obvious that the lines are not in the same plane. Which makes using the Working Plane tool difficult. In SU I tried several add-on scripts, but none created a smooth, continuous curved surface.

Ironically, out of desperation, I used the Terrain tool (for draping a surface over ground contours), and it worked the first time. But the complexity of the outlines apparently caused the various skinning tools to add some unwanted wrinkles, that become apparent when viewed from certain angles.

Empty outline in SU :

[img:left]http://home.mindspring.com/~gnomon/Loft%20outline.JPG[/img]

PS---In VW I set the 3D conversion resolution to Very High, in hopes that it would increase the number of segments of those warped curved edges. But the curves still looked pretty choppy on-screen. I haven't printed yet, so . . .

Edited December 20, 2010 by JHEarcht

[grant_PD]

I think what you want is to create a surface from curves. Plot your points where you know them to be. Join up your points with Nurbs curves, then select them and create surface from curves.

[JHEarcht]

Creating the curves is not the problem. The curves create themselves when I intersect two solids. My problem now is understanding how the Subtract Solids tool is supposed to work. The Help file describes the use of the Push/Pull tool, but doesn't mention the right-click command.

In the first shot below I have overlapped two solids. Now I want to subtract the Ellipse from the model, using the Context Menu. The second shot shows the result, without the ellipse. So far so good.

Next I want to select and delete the cut lines indicated. Which should make the faces disappear, so I can loft a new face between the remaining outer edges, as shown in the Empty Outline shot above.

But when I try to edit the subtracted model, the original ellipse reappears and the cut lines disappear. In SketchUp, both objects remain visible, so I can delete the one I don't want to keep. In VW I assumed that when the ellipse disappeared, it was dead and gone. But apparently the ghost hangs around to haunt me.

How can I edit the subtracted model without returning to the elliptical solid used to intersect and cutaway the unwanted parts? I want the ellipse to go away for good, but it hides after the subtraction, so I can't delete it.

Overlapping Solids ---

Ellipse subtracted from model ----

Edited December 20, 2010 by JHEarcht

[bcd]

VW 3d is based on solids modeling so you generally can't delete a face to reveal the void inside.

Right Click gives you access to contextual commands, commands that are available in the Menu Bar or elsewhere that VW figures you might be interested in based on your selection.

The haunting ghost is actually your friend and the solid operation history is part of the solid object until either VW can take no more or you Modify>Convert>Convert to Generic solids.

Double clicking an edited solid will reveal the last edit which can be really useful if you suddenly decide to use a sphere rather than an elliptical cylinder to perform the clipping, or if you want to reposition your cutting object.

If you want to further sculpt your model just perform another subtraction, slice, fillet (you'll loose the history by using fillets) etc.

You might find that using the Sub-Face mode of the Push Pull tool with get you where you want to go.

Also - it appears you are modeling a symmetrical object. By modeling one half of this and at the end duplicating and adding you will save yourself a lot of time and error checking.

Edited December 20, 2010 by bcd

[JHEarcht]

I have discovered that "editing" the subtracted solid involves going back through all previous subtraction or addition operations on the same object. This is a "feature" that SU doesn't have, and that I don't need at the moment.

Apparently, in order to avoid that historical regression, I need to purge the memory, or to convert the model from a Solid Subtraction to something else. I tried converting to a Generic Solid, but that left me with an un-editable object. Any ideas for how I can go forward, instead of backward, to edit the model?

[mike m oz]

Sculpting by carving away parts of the block is not the way to do this. Heed Gran'ts suggestion.

[Kaare Baekgaard]

The shape does not look too difficult. Build the base last and focus on the top. Loft the basic shape from curves without the cutouts, which are easily done later.

Use as few vertices as possible for the curves - or remember to rebuild the curves before you loft them. That way, they are more likely to make harmonic surfaces. (Sometimes it is best to rebuild two curves to equal number of vertices before a loft).

Use the extract tool to get the edge curves to loft additional surfaces until you can make a closed figure.

Try to avoid the 'create surface from curves' if you can help it, as it tends to build messy surfaces.

'Add solids' the surfaces (sometimes you have to do this one by one) until you get a closed solid. If you extract any solid object from this base solid - and it becomes hollow - it is not a propper solid.

Usually the dual connect tool can help to align the edges of individual untrimmed surfaces, so that they will close properly. Use the 'position match' option. Usually you will have to pull away a single edge vertice of one of the surfaces with the 3D reshape tool in order to 'dual connect' two surfaces.

Once you got the main solid right, it is easy to carve the holes and create a base.

There are a million more ways to do the figure, but this one should work.

Edited December 21, 2010 by Kaare Baekgaard

[JHEarcht]

OK, I give up. Sculpting a solid object is more intuitive for me to produce a non-orthogonal object. But I see that VW is not setup for that method.

Now I'm trying to trace over the edges of the solid to produce new independent faces. I tried to create a Nurbs curve by clicking on end points of each segment of the curved solid edges. That proved difficult, so I tried to place a 3D locus at each endpoint to serve as guide points. But then I got an error message : "locus is not visible". I don't know why. So I guess I'll have to do it the hard way.

The lines and curves needed to create new edges and faces are right there in front of me, but I can't get to them. And I can't imagine how to create them from scratch as 3D non-coplanar curves. I tried to Decompose the solid, but it shattered into a thousand pieces rather than a few major surfaces.

KB, how do you "rebuild" a curve? How do you use the Extract tool to get edge curves for lofting? When I use the Extract Curve/Face tool the OIP says "no selection - locked". Where is the "Create Surface from Curves" command? Where is the Dual Connect tool, and the Position Match command?

PS---Why is everything I create from the Solid Object automatically Locked, even if I cut and paste it outside the original object? The Lock/Unlock command has no effect on the new lines or surfaces.

Edited December 21, 2010 by JHEarcht

[bcd]

JH - have you tried importing your Sketchup Model into VW, scaling it to suit, setting a locus point at the various vertices and working from there with your nurbs curves/surfaces?

[JHEarcht]

JH - have you tried importing your Sketchup Model into VW, scaling it to suit, setting a locus point at the various vertices and working from there with your nurbs curves/surfaces?

Yes, but nothing was imported. I tried to import several SU files onto a new layer, and nothing happened. So I didn't waste any more time on that gambit.

Edited December 22, 2010 by JHEarcht

[bcd]

It works. Perhaps back-save the SU file to a SU version VW 2010 can recognize. (SU 6 I think)

[Benson Shaw]

JH, I think learning to use NURBS and lofts would help you. As always, there are many ways forward in VW. I made a quick sample in VW2010.

If possible, show us what you come up with, however you do it. Even if you revert to SU.

-B

[JHEarcht]

JH, I think learning to use NURBS and lofts would help you. As always, there are many ways forward in VW. I made a quick sample in VW2010.

I am trying to use Nurbs curves to recreate the edges of the solid object. It's very slow and tedious compared to the quick'n'easy sculpting method in SU.

Plus, I'm having difficulty joining the corners into a single outline. How can you connect/combine, or compose curves that are not in the same plane? In SU that was not a problem; it would just snap to points in space.

Plus, how can you draw a line connecting two endpoints that are not in the same working plane? Whenever I draw a straight line over the solid object the highlight stays where I put it, but the line displays parallel to it, and several inches away. Like a ghostly doppelganger.

Nurbs outline image below. Not connected at some corners, and some apparently continuous curves are not connected end to end, even though they were snapped together. The pink things are text boxes that were deleted, but wouldn't disappear. I tried lofting as is, but nothing happened.

Oh well, back to the old drawing board.

Edited December 22, 2010 by JHEarcht

[mike m oz]

Use the Nurbs tool from the 3D Modelling toolset rather than the Line tool as this will snap to 3D points in space. If you want corner vertices set the Corner Degree preference to 1 before you start drawing.

You can find more information on nurbs modelling in the 3D PowerPack information here:

- Movies: http://www.nemetschek.net/3Dpowerpack/qtexamples.php

- Tips: http://www.nemetschek.net/3Dpowerpack/tips.php

[mike m oz]

JHE can you post the SketchUp file here so we can see exactly what it is you are trying to model. That would make it easier to advise you on how to best go about it.

[Benson Shaw]

JHE Here is another file, with a png image.

The wireframe shape was made by drawing 2d spline curves in various views, converting them to NURBS Curves, changing views as nec to move them into place (most needed no moving). Except the 3 dark green connectors in the cap are NURBS curves snapped to the endpoints of leading knife curve (light blue) and upper triangle.

Surfaces were made by selecting the 3 or four bounding NURBS and invoking Model>3d Power Pack>Create Surface from Curves. Then I punched out the opening with a 2d ellipse with the 3d Project/Trim tool.

Try making surfaces on the other wire faces. Select the 3 or 4 curves then duplicate the selection, then Create Surface from Curves to save the curves so you don't have to extract them if you need them later.

In the vwx, click through the Top, Front, Right views to see how I used those black 2d objects as guides.

Hth

-B

[JHEarcht]

OZ, an image of the SU model is in the first post above. Creating the desired shape by sculpting was pretty easy in SU. The problems arose when I used various skinning add-ons to fill-in between the curved outlines with a compound curved surface. All of them had unwanted wrinkles (artifacts) in the otherwise smooth skin.

The outline posted just above was created from Nurbs curves. But connecting ends and corners didn't work as expected from my experience with VW 2D or with SU. I even used a Nurbs curve to make a straight line between two curve ends, because the 2D line tool produced bizarre results (the ghost twin mentioned above).

I think I'll have to drop it now, until after the holidays. Maybe the PowerPack references will help me understand the abilities and limitations of the 3D tools. "When all else fails, read the instruction manual". But not the Help files.

[mike m oz]

It looks to me as if Benson has produced what you want (or at least what I think you want). To complete it all you need to do is mirror it to get the other half.

To 'skin' the arched opening:

- Use the Extract tool to get the outlines of the arched opening.

- Ungroup these and compose them into two single nurbs curves.

- Loft between these two curves.

If you really want to understand and harness the power that exists in the 3D Powerpack capabilities make the time to view the movies several times and then do the tutorials. The return for effort is worth it.

Edited December 23, 2010 by mike m oz

[JHEarcht]

OZ

I haven't had time to review the PowerPak tutorials. But I finally got all the corners to connect into a single Nurbs curve. When I select one edge the whole thing is highlighted. Unfortunately, when I invoke the Create Surface From Curves command, the result is a message : "Surface could not be created from curve network."

Is this function limited to four sides? My outline has 5 or 6 Nurbs Curves, including the straight lines (3D polys) converted into Nurbs curves.

Even the flat surface at the top, composed of 3 Nurbs curves, does not respond to the Create Surface command. Even though the OIP says "Nurbs curve", the Interpolate Surface command says "you must select a Nurbs curve".

Since the Grinch has stolen VectorWorks 3D tools, I may as well shut down, and go to New Orleans for a Cajun Christmas. I wish you all a merry holiday!

[Kevin McAllister]

A few things to look for when making a surface from Nurbs curves -

- I believe all the Nurbs curves need to go in the same direction. Click on the Show Direction checkbox in the Object Info Palette to see the direction arrows. Use the Reverse Direction radio button, also in the Object Info Palette to make your curves consistent.

- I have had more success using Modify>Combine to combine various curves first. This is also a good way to discover which curves don't quite touch. If you are able to combine all the curves into a single curv, the Create Surface from Curves command will still work.

- I have found that it can be finicky if the curves are different degrees. Look in the Object Info Palette and see how each of your curves compare. Often you can increase the degree, not alter the curve, and get them to combine successfully.

Hope this helps.

Kevin

[islandmon]

Granted my approach is pretty basic ... but here it is:

1) All surfaces are composed of Hausdorf fractal triangles

2) All triangles are composed of {{{{ tan-sin-cosine }}}}... edges & arcs

3) All Menger volumes are composed of fractal polyhedra

4) All fractal systems are scalable.

5) Smoothiness is a function of the Hausdorf Dimension.

6) The Hausdorf Dimension is only constrained by the computational limits.

7) Iteration : addressing :: frequency-modulation : smoothiness

What this implies is that the simplest approach will lead to the most efficient results.

[Benson Shaw]

JHE

Have a great cajun holiday!

You may have discovered all this already, but:

The Create Surface command should work on a selection of curves as long as they are end snapped. There may be a limit, but 4 or 5 curves is within that limit. The Create Surface command also should work on a single, closed NURBS curve, such as one composed from edges of your knife edge face (but do not include those cap edges connecting to the top of knife to top point). Experiment with individual curve direction, but it should not affect command success.

Fewer points (degree) in the curves is better. Drag vertices or adjust weight in the OIP to modify curve shape and/or surface curvature.

Your two triangular cap faces rising from the knife edge faces should be created as a separate object(s)

The Create Interpolated Surface command converts an existing NURBS surface (not curves) to a new surface with control points on the surface and edges.

If your model is not too proprietary:

Paste your model or at least the bounding curves into a new file and post here for others to try.

-B