So I talked to a few people who are much more experienced than I am in the use of MoI. I'm hoping I can get some additional guidance.

I'm learning to expand my knowledge by re-producing some Cold Navy starships based on some blueprints. They have some more complex hull designs and are pushing my knowledge base.

I'm attaching my 3D file, which has the base hull and single line overlayed upon it. It has been recommended that I try using a more trapezoid shape to eliminate the crowning problem I was having before.



I'm having a few problems when I try this. First, I get a long sweep that extends way off the object and doesn't seem to be staying on the curve, not sure why? Secondly, when I try to do a boolean dif, and delete the swept object, it won't delete the swept object from the main shape?

As a side note, I just put in my order for the software, and then upgraded to the 2.0 beta as well. I create the hull and line in the 1.0 version of the program - not sure if that is an issue?

I'm attaching my 3d file as well, I'm hoping someone like Otterman will come along and maybe grab my file and work a little magic so I can see how he's doing his excellent work (awesome panel lines on complex hulls)!

Thanks,

Ryan.

Hi Ryan, could you please also post the 3 background images: "side.png", "front.png", and "top.png", other people will not be able to see them unless you either post them as well, or in v2 there is an option under image properties to include the background image baked into the 3DM file - if you set that option then you don't need to post them separately but by default with the images as an external file reference others won't see the images.

- Michael

Hi Ryan, also for several of the pieces that look like this:




Are those supposed to be kind of depressed panels?

If so, then you should be able to use the same technique that I showed you in a previous thread here:

http://moi3d.com/forum/index.php?webtag=MOI&msg=3208.2

Won't that same technique work for you in those cases here as well?

There is also some illustration of that technique (draw a closed curve, use Trim to cut the object, extrude the cut piece, then delete the front face and join the depression to the main body) in this other thread here:

http://moi3d.com/forum/index.php?webtag=MOI&msg=3024.4

- Michael

I probably confused the situation with the drawings in there. I did however go back and embed the three images, just in case someone wants to see them.

Hopefully this will clear it up.

I can get the recessed areas to work - but the line highlighted in yellow is where I am struggling. I've tried sweeping two shapes (a trapezoid and a square) and neither seem to work? In my other design, I was able to draw a line, sweep another shape around that line, then do a boolean dif, followed by deleting the shape to create a recessed channel in the solid object.

Since my objects are now getting more complex, it's not working any longer?

Here is the drawing showing the two shapes I've tried sweeping, and the rail I've used to sweep around.



Hopefully this helps clear up my question?

Ryan.

Hi Ryan, also there are some varieties on that technique that you can use as well, like instead of trimming one single piece, you can do something like starting with one flat outline drawn in the side view like this:



Use Construct > Offset to create a second one that is some thickness away from it:



Now select the main body (which you probably want to have set up as only a half and then mirror it when you have it all finished), and use Edit > Trim to cut it by both those curves:



Delete that in between part, and then move the inside piece inwards a bit:



Now Loft between the edges to make the side pieces, then Join those all together:




That's just to give you an idea on a variation. But fundamentally to make these kinds of things you will be cutting the hull in various ways, either by drawing curves and using Trim, or in some cases it may be easier to model the cutting piece as a separate solid on its own and then use a boolean operation to carve it out of the main body.

- Michael


EDIT: I hadn't seen your new message when I posted this one...

Hi Ryan, ok I see what you mean now, sorry I didn't understand it was that one particular sweep that was the problem.

So it looks like the problem is that your path curve is not actually a smooth curve, the different segments do not have the same end tangent directions where they meet up.

That's going to make your sweep be segmented as well and have little gaps (and currently in v2 have some extension problems where the new corner mitering is kicking in and not working entirely yet) between the pieces.

In order to get a nice smooth sweep result, the path curve should be made up of segments that are tangent where they touch each other.


How was that rail path created, was it created as a projection of a line through the main piece? Probably the surfaces on the main piece are not quite smooth to one another.

Also how was the main piece created, was that done by a sweep in v1?

Sweep in v1 had some problems where it was sensitive to the control point spacing between 2 rail curves and could end up kind of bunching things together. For example if I untrim your pieces and turn on control points, you can kind of see they are sort of slanted and not very regularly spaced:




If you're sweeping these sort of one piece at a time, that may not be so good because it can be hard to make things that meet up smoothly when you do it like that.

Could you maybe post some of the curves you used to create the main body so I can see more of what you were doing from the start on this model?


Thanks,
- Michael

Yes on both accounts. I don't have a version that shows the lines, but in essense I took a shape that was a trapezoid with rounded corners (if you're looking at it from the front side) and swept it around two rails with a third scaling rail as well to help get the shape right.

Yes, I did a projection of a straight line onto the hull, which is the yellow rail I highlighted on the second drawing which was where my problems started.

Would it be best to start over in V2 and recreate my hull shape - would that even fix my problem?

Hi Ryan, yeah the sweep in v2 does solve that problem and shouldn't get that kind of twisting effect in it.

It probably is a good idea to recreate the body and get it to be kind of cleaner to start with, usually if there are problems with big pieces early on it will trickle down and cause additional problems when more stuff is derived from it.

But also I've attached an new version here with just that rail curve redrawn - I did by drawing in 3 line segments, then using Blend to put in the connecting pieces (blend will guarantee a smooth piece) and then mirroring that.

If you try sweeping with this version you should get the result you were looking for I think.

- Michael

Hi Ryan, one other note though - you are going along with the right general idea here, to build the thing as a larger piece like this:



and then to slice off the ends, rather than trying to draw the sliced off end first and then try to create surfaces from that.

So you're definitely going in the right direction, but in this case your starting surfaces didn't end up too good, partly because of a problem in sweep in v1 but I'm also not sure if you might have had a little wiggly area in some of your starting curves.

If you are going to give redrawing the thing a try, you might want to post your initial curves here so I can take a look and maybe give some advice on that initial shaping.

- Michael

Yep, I tried sweeping the trapezoid shape around the rail, worked like a charm now.

Thanks Michael, appreciate the help.

Ryan.

Argh, too late!

Here's a trick I learned while making a Vaygr BC. (time is brief, daughter in tub, pictures later if possible)

Do a side view
Draw a set of panels lines
Use the lines to cut into the ship (boolean diff)
Do a one dimensional scale of the panel line chunk to shrink it into the middle of the ship
Use boolean union to join the main part and shrunk panel line section back together.

Nope, you're not too late! I'm still having problems - so I decided to reboot the project and start with rebuilding the hull in the v2 software.

Per Michael's request, here is my initial shape and three rails. Rails 1 and 2 are what I use for the sweep, rail 3 is scaling rail I'm using to widen the sweep a bit.



My next step will be to make some cuts using boolean dif commands to get back to the shape I had in version 1.

Then I'll give some panel lines a go. Otterman, would still love to see some detail shots of how you get yours to come out so good!

Ryan.

Otterman,

So I think I follow how you're doing it. I tried a slightly different way which seems to be working. Because I have a very odd shaped hull, I made a copy of the hull and reduced it by 10% and placed it inside the other hull (aligning the best I could by eye to put it right in the middle of the other hull in all three directions). Then I did what you recommend, I created some panel lining, did a boolean dif and then cut out the lines from the outer hull, leaving the inner hull uncut and helping to form the channel.

Seems to be working OK, I'm going to try a few more lines and see how it continues to work.

Thanks for the insight, really appreciate it.

Ryan.

OK - after an afternoon of work, I've got the front of the hull pretty much banged out. I used a variation of what Otterman had recommended, and I think it came out pretty good. Since I've never actually 3D printed something, I'm not sure if my panel lines are deep enough/too deep.

Here's how it is shaping up.



So far, so good.

Ryan.

Hi Ryan,

> Per Michael's request, here is my initial shape and three rails. Rails 1 and
> 2 are what I use for the sweep, rail 3 is scaling rail I'm using to widen the
> sweep a bit.

Thanks for posting those - yeah in v2 the sweep result is looking a whole lot better in its internal surface structure.

In the v2 sweep, if you turn on surface control points (for solids you usually need to use Edit/Separate first to break it into individual surfaces before points will turn on), you get this kind of result:




That's a lot better than the previous one that you did in v1 that had a lot of shearing and slanting in it.

So that's good to know that the sweep update in v2 is helping for that problem.


It looks like you have made some great progress!

One possible other general tip - you may want to focus on building something like this as 1/2 only and then mirror it at the end to produce the other half instead of working on both sides during the regular modeling.

- Michael

Ryan,

Regarding the depth of your panel lines, I think that they seem rather deep indeed, which might be OK on the hull itself to give the effect of cladding or armor often seen on Sci-Fi spaceships, but for panels, most should not be recessed at all. You might want to delineate the panels with a double contour and have that narrow band recessed instead, leaving the panel itself flush with the hull. Unless the effect you want is more like an open bay.

Jean-Paul