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Old 22nd March 2015, 03:32 PM   #1
jleslie
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Default baloney slices the other way,

well starting from scratch with the the line drawings of the ship, I can build the sections, but its long and laborious. I was hoping to be able to convert from existing sketchup easier:
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Old 24th March 2015, 08:38 AM   #2
Andy
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Default Re: baloney slices the other way,

Do you mean convert from Sketchup? If so, you should be able to export .obj and import it into AC3D.

If you have a series of line profiles, you can use the convex hull (Vertex->Create-convex surface/object) to make surfaces over a shape (note that it works convexly, so for concave shapes, you may need to do it in parts and delete extra surfaces that are created).
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Old 24th March 2015, 09:13 AM   #3
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Default Re: baloney slices the other way,

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Originally Posted by Andy View Post
Do you mean convert from Sketchup? If so, you should be able to export .obj and import it into AC3D.

If you have a series of line profiles, you can use the convex hull (Vertex->Create-convex surface/object) to make surfaces over a shape (note that it works convexly, so for concave shapes, you may need to do it in parts and delete extra surfaces that are created).
"Do you mean convert from Sketchup? If so, you should be able to export .obj and import it into AC3D."
yes I can do that no problem using .dae, my issue is the polygon count is out of control, I need it to be far less. I really want bascially a bunch of conic sections the top and bottom being just a single polygon, and the sides just a wrap of the two polygons. In its simpilest form, a cylinder, you end up with 3 "polygons" 2 circles, and a rectangle that wraps around the edges of the circle. If you look at my picture, you can see that is what I've done for my thick "baloney" slices.

"If you have a series of line profiles, you can use the convex hull (Vertex->Create-convex surface/object) to make surfaces over a shape (note that it works convexly, so for concave shapes, you may need to do it in parts and delete extra surfaces that are created)"

this sounds very interesting and I would love to see a tutorial or video on this technique, is there one available or can you give some more step by step instructions?

as you can see in the attached pictures, doing it by hand is not coming out too well for the bow...
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Old 24th March 2015, 12:33 PM   #4
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Default Re: baloney slices the other way,

It's looking great from here.

The convex hull function creates surface around a selection of vertices. Imagine a balloon having the air let out of it, over a load of points - it will shrink until it can't any more. Any 'internal' points are not used to make the shape but any that touch the 'balloon' will define the outside of the new surfaces.

There's an example in the manual - access this from the Help menu inside AC3D. see Operations on Vertices->Create-convex surface/object.
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Old 24th March 2015, 01:59 PM   #5
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Default Re: baloney slices the other way,

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It's looking great from here.



There's an example in the manual - access this from the Help menu inside AC3D. see Operations on Vertices->Create-convex surface/object.

thanks, but its all trial and terror...

its very time consuming and I was hoping for a faster way of doing it. currently I trace the baloney slice in 2d with the multi-point poly shape, then extrude and then drag the points of the new polyside down to the new baloney slice. However this isn't very smooth and I then have to do a lot of tweaking to round everything. I was hoping the Vertices->Create-convex surface/object will be faster without adding polygons.
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Old 24th March 2015, 02:28 PM   #6
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Default Re: baloney slices the other way,

Create a new line over each section of the bitmap and position these along the hull until you have a 'vertex skeleton'.

In vertex mode, you can select two of the lines and use the convex function. That will form a shape around the vertices. Switch to Surface select mode (press 's' and 'v' to switch modes, it's a bit quicker) then select and delete any extra surfaces - mostly from the front, back and top. The keel is concave so you'll need to do these sections in more than one go.

Actually it might be better to select the vertices in horizontal slabs. You may be able to make the majority of the shape in one go - apart from the concave section.
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Old 24th March 2015, 06:14 PM   #7
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Default Re: baloney slices the other way,

thank you andy for your advice. I can get the vertex->create-convex to work on my one model and now I see what you mean about the concave vs convex. the create convex wont shrink wrap! I tried the other sketchup conversion I had that I sliced the baloney longitudinally, but the vertex-> create-convex gives me an error (see attached) I tried its advice, and it removed 95 vertices, but it still wontvertex->create-convex.

Also while I have your ear, another annoying problem I run into it when I try and combine surfaces (the 'c' command under surfaces control) I occasionally get the error about surfaces need to share a vertex (see other attached) but near as I can tell they do. Any advice on why I get this message? TIA- jleslie
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Old 24th March 2015, 08:47 PM   #8
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Default Re: baloney slices the other way,

ok, ac3d crashes a lot with vertex->create convex surfaces (I'm using version 6.8.14 on a windows 7 pro x64) meanwhile back onto the first sketchup model when I do the longitudinal baloney slices (make a rectangular cube, then click on the rectangle, then the ship, then object->boolean->intersect) I get the thick slice, but when I then grab the vertexes, and do a vertex->create convex surfaces I only get half the convex surface:

to make sure I grabbed all the vertexes, I grabbed the baloney slice as an object and then switched to vertex control. I can't even imagine why the convex surface split were it did in the second place...
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Old 25th March 2015, 07:41 AM   #9
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Default Re: baloney slices the other way,

Have you tried using the latest AC3D version? It will have better compatibility with Windows 7.

It's difficult to tell from the image but if you are getting vertices that are not used in the hull then they are 'inside' the space created by the others.

Post or email me the file and I'll take a look.

make sure all the surfaces are in the same object and the vertices are shared before combining surfaces (use Object->merge and Object->optimize-vertices).

Last edited by Andy; 25th March 2015 at 07:45 AM.
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Old 25th March 2015, 08:50 AM   #10
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Default Re: baloney slices the other way,

"It's difficult to tell from the image but if you are getting vertices that are not used in the hull then they are 'inside' the space created by the others."

this might be my problem. I'm not sure how to tell or fix.

"make sure all the surfaces are in the same object and the vertices are shared before combining surfaces (use Object->merge and Object->optimize-vertices)."

tried this. no change.
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