Import Lines Plan to Rhino

[ivansalasj]

Hello,

I have with me some lines from a nice classic sloop and I want to get these lines into rhino and start working on them. I have tried to use maxsurf and prefit but do not like that path. I am sure that many of you have faced this same problem so if somebody could give some advice that would be great!

Thanks very much,

Ivan

[yipster]

did you read polarity's old good rhino hull tutorial?
http://boatdesign.net/forums/showthr...ighlight=rhino

[ivansalasj]

good tutorial but it does not solve my query. I have a lines plan with me and I would like to find out what is the best way to but these lines into rhino, maybe by importing a picture (like you can do in maxsurf), or any other way.

thanks for your reply

[Raggi_Thor]

You can use a raster image (of the lines plan) as a background in Rhino, but then you can't zoom and pan...
I use to attach the image in AutoCAD or BricsCad and then trace the lines as splines or plines, then import the dwg into Rhino for fairing and the make a surface to match the lines.

[Crag Cay]

I have done this hundred's of times with MaxSurf and can't see what the problem is. However I don't use Prefit.

I scan the lines plan and then use Photoshop to make sure the line are square and regular. I even get rid of any details that I don't need to reduce clutter. I make sure some clearly identifyable scale points are obvious.

I then import the plan, profile and body plan as seperate image scans into the background of their corresponding window. I then descide on the number of surfaces I need, set the sections, waterlines and buttocks up to correspond to the original plans, and start modelling.

The better you are at judging how complex the control net needs to be, the easier it is to descide which sections are needed. Sometimes you only need four or five sections and if these are close to control columns, you will have an easier time working in the blody plan view.

As MaxSurf will allow you to achieve a higher level of fairing than was possible on the original plan (which would have been lofted before building), you have to decide when to stop trying to accurately 'trace' the original and start getting the best fit fair surface.

[ivansalasj]

Thanks for your help, i will try importing the image to autocad and match my lines with splines and finally i will take them to rhino.

Crag, you directly start with a surface? i rather get the lines first and then fit a surface/s to these.

[SailDesign]

ivansalasj,
I used the AutoCAD/Rhino approach for the Vendee Sardiniere http://www.boatdesign.net/gallery/sh...500/ppuser/909
and it worked fine. A little time-consuming, but good results. I DID (he admits under pressure) drop back in to AutoShip for a final fairness check....
Steve

[Crag Cay]

No, I work straight away with surfaces.

If you have a pronounced stem / keel as in Steve's example, then you will almost certainly have to use a seperate surface for this. Either extend it well into the volume of the boat and then the surface representing the planking will be another surface which itself will extend to the centre line. The intersection line will be the rabbet line. Or try and model the rabbet line with the upper/inner edge of the stem/keel surface and then bond the lower edge of the planking surface to it. Depends to a degree on the nature of the keel.

[water addict]

Perhaps a bit off topic, and don't mean to hijack the thread -
One comment I have about Rhino and modelling, just curious if anyone else has had the same issue.

I've made planar cuts on surfaces and lines in Rhino at specified planes, i.e. waterline or bulkead cut at specific distance above baseline or distance aft of FP. If I query the geometry at the cut, most of the time the cut is not where I specified it to be, small errors are there. Example: cut a curve or surface at 10 feet above baseline, query the cut geometry and you get 9.994 or 10.003 or some such. While in reality this is not significant, it can be a major nuisance while building a model particularly for analysis and have to go back manually and join the parts where not connected.

Anyone else have this trouble? Autocad gives me this same trouble as well.

[quicksail]

You can import a PDF file into rhino. Just save the linesplan as a PDF then right click on it and say open with Rhino. It will open the pdf in Rhino and you will be able to modify, print, whatever you want.

I use PrimoPDF, just load the google and do a search.

Hope this helps.

[Raggi_Thor]

Originally Posted by water addict

.... If I query the geometry at the cut, most of the time the cut is not where I specified it to be, small errors are there. Example: cut a curve or surface at 10 feet above baseline, query the cut geometry and you get 9.994 or 10.003 or some such. ...Anyone else have this trouble? Autocad gives me this same trouble as well.

Rhino uses the tolerances that you specify for trimming and projections etc.
One neighbour here worked in meters and had tolerances for mm, something like 0.01. When he trimmed two surfaces Rhino would be happy with errors less than 0.01 meter!

AutoCAD is more accurate, but then it's not as capable as Rhino..
I think AutoCAD has problems with objects lying very far from the origin.

[snakefeet]

Raggi Thor, I'm curious; why do you say that you can't zoom or pan when using a raster image for a background inRhino? I trace over scanned images in Rhino now & then and have never had a problem.

Autocad is good if you want to print a scanned image along with CAD work - escpecially if you want it at a specific scale. But for tracing I'll take rhino every time. To be fair, that may be a question of my taste rather than the programs' actual capability.

[ivansalasj]

i have used raggi's suggestion: scan body plan to autocad, i have created points following the sections, i have joined the points with spline, i have imported the sections to rhino as a dwg (2000LT) and I am now rebuilding the lines to a lesser degree but i know i will be facing another difficulty due to the nature of the lines. The lines are for a classic yacht with a long keel and the stern and bow sections can easily be rebuilded with a 3 degree 5 point curve but the sections in the mid body of the yacht will surely need more work to get them closer to the originals, is it a good option just to use a higher degree spline, i am worried about using different degrees since it will create problems when lofting a surface to the sections. Any suggestions when modelling these types of hull forms?

Thanks

[Raggi_Thor]

Originally Posted by snakefeet

Raggi Thor, I'm curious; why do you say that you can't zoom or pan when using a raster image for a background inRhino? I trace over scanned images in Rhino now & then and have never had a problem....

Maybe I was doing it wrong?
When I tried to use a raster image as a background in Rhino it was a constant size in the viewport. When I zoomed the background did not change. So I was not able to zoom and pan while I was drawing.

[Raggi_Thor]

Originally Posted by ivansalasj

... i am worried about using different degrees since it will create problems when lofting a surface to the sections...

My experience is that you can use the number of control points you like (or need) for each curve. When you loft a surface you can chose "loose lofting" and rebuild.

Remember that boats has never been built accurately to the lines plans or the offset tables. Most boats would be faired on the floor, so you should accept some deviation from the lines if that makes a smoother surface.