2D => 3D hull... need to read up how this works...

Hi all,

I have the following lining (see attached image, they come origionally from a old drawing) in 2D in AutoCAD and now I need to create a 3D model of the the lining (in Pro Engineer Wildfire). Where can I read upon how these lining are projected so I can setup the same projection in Pro/E to make the hull?

Ries
(Note: I am a newbie on this)

 

Sections

Looks like you have hull sections. First thing is make sure it is to scale. If not re-size it so that it is.
What you need to do is to give the sections elevation to create a 3d form. Pick a point on the geometry for your origin and move the curves to 0,0,0. I like the centerline at the keel but it is not important as long as it works for you.
Next take each section, determine how far away from the origin it is and move it that distance in the z direction. In other words lift each section off the page, away from the transom. After you've done so you have the raw materials to build surfaces. Add curves for the centerline and for the sheer and whatever else you need to build surfaces in Pro-E.

djs

 

dereksirecim,

thanks for your quick response. I'll try this tonight and see how that works. Basicly what I am trying to do is project the 2D lining on a 3D surface without picking each point seperatly...

Do you know any website where I can read upon this? How do they normally create these lining?

Ries

 

Not easy

Nobody said it is easy. It's not hard either, just time consuming. You have to grab each curve separately. They might be continious curves or they may be a bunch of tiny segments. Take the time to organize things. If they are tiny segments, try to join them. If you can't join them maybe it will be easier to draw new curves through the endpoints of the segments.

If the program can do it. Isolate each curve on its own layer. The layer name should correspond to the station number to avoid confusion. Keep in mind your final goal to decide what level of accuracy you need.

Do you want to build this model? Do you need to do hydrostatics or a weight study?

You may not need to use every station on that body plan in order to develop a hull model with the accuracy you need.

You need enough knowlege of Pro-E to make a plan for building the surface model. Find a Pro-E expert to give you tips on how to proceed. Looks like you have everything you need to do a simple nurbs surface thru curves - if the curves are located correctly. You'll need the profile view to position the transom section. Use the centerline and sheer as guide curves.

The reverse process is how they are usually created. You develop a 3d model that you like, then chop it up into sections in three planes to describe the surface in 2d. Plan, profile and body views. You could also add diagonal sections if it helps the reader understand the shape.

good luck

djs

 

I agree with you djs, although my experience is the "cleanest" lines come from the model with as little points as possible.

The drawn sections in the 2D file are most likely for contruction or to "read" the surface in a 2D representation. That does not mean you need them all to draw a new one. With pro-e you have enough tools to reproduce the surfaces.

 

Fitting a (NURB) surface straight away through these curves often leads to a poor surface at the bow and surface, specially if you have a bulbous bow or gondola fitted at the stern. Another simple solution to recreate the lines would be to use a hull design program that is capble of showing background images.

You could import the existing autocad lines as a background image and create a new default hull with similar dimensions on top of that. The "only" thing you'd have to do is add stations to your new 3D hull at the same locations as the ones displayed in your autocad file and keep fairing your 3D model until the stations in your 3D model exactly coincide with the ones of your background image.

It is a slightly labour intensive way of "tracing"a hull, but you have much better control over how many points you want to use in your 3D model and how they are distributed over your model. This makes it much easier to obtain a fair hull surface. There are several programs capable of doing this. I've recreated a fishing trawler this way in approx. 4 hours.

 

Just thought of something.....

The lines appear not to be created in Autocad. I image they are created with a different piece of software. Do you have access to the original files ( or any files for what it's worth)?

 

Here is a screenshot of the new stations (light green) drawn on top of the background image I was talking about.

 

djs, Sander and Martijn (sounds dutch?),
thanks for your responses and my excuus for my late response.

I am not considering myself a expert in Pro/E but just patiently in working and figuring out such a cool tool. The biggest problem I am facing now with is that I cannot import a reference as I can create with autoklad. But simply adding a reference line does the trick which I later remove when a line is constrained. It takes about 5 minutes now per line. So I should have everything imported in a couple of hours. Then I can do some basic fairing and such.

The origional lines come from a drawing back in the time nobody even knew how the word 'computer' was pronounced, and not know what it was. These lining where scanned in and put under a autocad drawing. Now it's my task to start making a hull out.

When the hull is ready I'll post a complete image of it.

Ries

 

Martijn,

is freeship capable of importing the hull as accurate as possible from the autocad lines i have?
OR should I import them in freeship and do the fiaring in freeship?

Ries

 

Ries,

You can do both, but if I were you I'd do the fairing inside the hull modeling program. It gives you more control over how many points you use for defining the hull geometry.
Less points means easier to fair (and faster).
However there is an optimum between the number of points needed to accurately describe the hull and the number of points needed to produce a smooth hull rapidly.

 

Update...

Here is a litle update what I have been done.
The hull is now closed and all autoCAD lines match the hull lines. No gaps anymore.
However fairing still needs to be done and at this time I am not sure if I should use pro/Engineer or any other tool.

Also I need to make a surface on top of these lines, early attemts failed but properly because I pressed the wrong buttons.

Cheers,
Ries