How to create a ship model with perfectly smooth surfaces?

Hi all, I am currently drawing a 3D ship model using Autocad 2008. I am using loft to create surfaces for the ship. As the result, I discovered that some area on the complex curved surfaces aren't perfectly smooth. For your information, I used loft command across 10 cross sections at once.

However, I also tried to create the complex curved area using meshes between those 10 cross sections, with using edgesurf and created 9 indivual meshes. And the surfaces seem much smoother than I created using loft.

How should I overcome the problem? I can't use the mesh to make the model because I need to get the sections from it (lofted surfaces can). Or are there any better methods to make a model of a ship with lots of complex curves? Which I can obtain sections from it later......

Thanks.

Can you post a screenshot?

Would it be possible for you to use fewer cross sections?

The more cross sections you have, the greater the possiblity of warpage. Fewer cross sections will give you a smoother lofted surface. Just like a spline, the fewer grips you have, the smoother the spline.

Also, make sure your cross sections are positioned correctly. If you have misalignment, your surface will not be smooth.

Sorry I can't post a screenshot because I can't bring them back from office.

Thanks mod, I have done my surfaces with less cross section and yeah the surfaces seem smoother.

Now I complete the ship model using lofted surfaces, but when I tried to get their sections using sectionplane, it doesnt work on some surfaces. Lets say my ship model are combined from 16-20 surfaces, and 1-3 of the surfaces can't be "sliced" when using sectionplane command on the model, with error message planar lateral curve bla bla. Any idea on how to overcome them?

Offtopic : My home's Autocad2008 can't select items one by one but last time it could. For example when i click a line and move on to click the second line, the first line will be unselected. As the result, I have to select them at once or using shift key when selecting the second line, which is pretty troublesome. Any idea what is wrong with my settings?

Well, the answer to your second question is the PICKADD variable. Set it to 1 and you should be back to normal.

Not sure about the first question though. Maybe someone else has an idea?

Sorry I can't post a screenshot because I can't bring them back from office.

 

Thanks mod, I have done my surfaces with less cross section and yeah the surfaces seem smoother.

 

Now I complete the ship model using lofted surfaces, but when I tried to get their sections using sectionplane, it doesnt work on some surfaces. Lets say my ship model are combined from 16-20 surfaces, and 1-3 of the surfaces can't be "sliced" when using sectionplane command on the model, with error message planar lateral curve bla bla. Any idea on how to overcome them?

 

 

Offtopic : My home's Autocad2008 can't select items one by one but last time it could. For example when i click a line and move on to click the second line, the first line will be unselected. As the result, I have to select them at once or using shift key when selecting the second line, which is pretty troublesome. Any idea what is wrong with my settings?

I'm assuming you used a Body Plan to make your model via lofting and I'd be a little worried about accuracy if you skipped a few of the stations. Then again if you kept the sections when the stations showed more curvature (mostly bow, maybe stern depending on hull shape) it may be fine. I'd definitely overlay a few of the stations and see though.

You may want to try to Loft and use a few waterlines or buttock lines as "guides." The ony issue there is that AutoCAD might @#$% a brick while trying to do something that complex.

If you're going to try to get cross-sections of your surfaces, you could try using PLANESURFs to cut up a copy of your hullform.

Thanks mod the pickadd 1 works.

Yeah Hoozin, I do refer to Body Plan to make my model. I'm adding some stations myself at the curved surface (normally i use edgesurf-mesh for the area that required additional stations and get the curved lines, only 2 month working experience here :/ is there any better way to get more accurate stations?).

Hmmm I haven't try using waterlines and buttock lines as guides yet. Going to try it tomorrow hehe.

I tried to figure out how to use planesurf to get the cross-sections of the surfaces but I failed. Don't get how it actually works. Anyway now I am using sectionplane to get the sections, and "Generate 2D/3D section", then exploded it to delete the unwanted surfaces and block the desire lines again. Do planesurf works easier?

Offtopic: You work on marine design too? Do you know about "Ship Constructor" software?

Sorry I can't post a screenshot because I can't bring them back from office.

 

Thanks mod, I have done my surfaces with less cross section and yeah the surfaces seem smoother.

 

Now I complete the ship model using lofted surfaces, but when I tried to get their sections using sectionplane, it doesnt work on some surfaces. Lets say my ship model are combined from 16-20 surfaces, and 1-3 of the surfaces can't be "sliced" when using sectionplane command on the model, with error message planar lateral curve bla bla. Any idea on how to overcome them?

 

 

Offtopic : My home's Autocad2008 can't select items one by one but last time it could. For example when i click a line and move on to click the second line, the first line will be unselected. As the result, I have to select them at once or using shift key when selecting the second line, which is pretty troublesome. Any idea what is wrong with my settings?

The error message I mentioned when using sectionplane are "Lateral curve doesnt not intersect to_surface." and "Cannot section solid by non_planar section object."

Hmmm I haven't try using waterlines and buttock lines as guides yet. Going to try it tomorrow hehe.

This is just an idea, I can't promise anything. I've seen Loft get confused very quickly if you try to give it too many inputs.

I tried to figure out how to use planesurf to get the cross-sections of the surfaces but I failed. Don't get how it actually works. Anyway now I am using sectionplane to get the sections, and "Generate 2D/3D section", then exploded it to delete the unwanted surfaces and block the desire lines again. Do planesurf works easier?

It's not so much that you're using planesurf to generate the section. PLANESURF generates a 2 dimensional surface that you can then use to SLICE other objects. Then you can delete your extra surfaces, stuff you don't want to see, etc and just show the stuff you want. Again though, you'd probably want to do all that with a copy of your model rather than the original (like just about everything else when working in 3D).

Offtopic: You work on marine design too? Do you know about "Ship Constructor" software?

Yes and Kinda, respectively. I went to school for 4 years for Naval Architecture and Marine Engineering and as I put it, forgot to graduate. I got picked up by an Engineering firm as a designer and spent a few weeks doing a 3D model for galley equipment and then started managing drawings for a specific acquisition.

That's where I ran into ShipConstructor. We don't actually use it (though there is a standalone copy and license at one guy's computer) but the vendor that did all of our drawings did. I know a bit about the program because I've spent weeks researching it trying to find a solution to an issue we have with their drawings (came up pretty empty on that though).

This is just an idea, I can't promise anything. I've seen Loft get confused very quickly if you try to give it too many inputs.

It is ok, I will just use it as reference.

It's not so much that you're using planesurf to generate the section. PLANESURF generates a 2 dimensional surface that you can then use to SLICE other objects. Then you can delete your extra surfaces, stuff you don't want to see, etc and just show the stuff you want. Again though, you'd probably want to do all that with a copy of your model rather than the original (like just about everything else when working in 3D).

Oh,thanks...I will try to figure it out.