seeking need knowledge about developable surface programs

Discussion in 'Software' started by timber, Mar 2, 2014.

  1. Baltic Bandit

    Baltic Bandit Previous Member

    I've got copies of Inventor full version from 8 -9 years back. I used it to teach my son 3D CAD modeling.
     
  2. isvflorin
    Joined: Nov 2009
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    isvflorin Junior Member

    user friendly cad

    Hi All,
    just throwing in my 2 cents. First, a disclaimer - I work for Evolute.
    I have been testing cad platforms for marine design for quite some time, my daily work is CAD, freeform shapes, boat design and complex geometry in general. I haven't yet found a more user friendly software than Rhino. It tops everything, in price, staff friendliness, scripting possibilities, geometry core. Where Rhino sucks , other developers fill in the gaps, like we do, and complete the package with 3rd party plugins. We recently just filled in the gap of developable lofting in Rhino, which was far from optimal.
    Now - my intention is not to advertise our software, just to inform you of what is out there for Rhino, so you can google a YouTube video from the company Evolute, called introduction to D.Loft.
    If this gets wiped out as cheeky advertising I apologize, however, on this forum I only represent myself and not my employer.
    Cheers,
    F
     
  3. TANSL
    Joined: Sep 2011
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    TANSL Senior Member

    Isvflorin, I've been looking website Evolute and the truth is that there are very nice things. As for the bulbous bow that appears there, sorry to say that's tacky in shipbuilding. I am convinced that Rhino makes things better. That's why I propose, on surfaces for boat, you may have more care with the softness of the shapes.
    Another question: does your software naval architecture calculations?. For instance, can you calculate the KN values ​​and draw the cross curves of stability?.
    Thanks for your answers
     
  4. isvflorin
    Joined: Nov 2009
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    isvflorin Junior Member

    Hi again,
    regarding the bulbous bow, it is just a demonstration of a technology, the purpose was to make things cheaper using developable surfaces, forming double curved surfaces in metal is quite costly. Secondly, we don't produce any real naval design software, our software focuses on core geometry, so you can only use it to create, in this case, developable surfaces that can be then exported to whatever cad platform. On the other hand, any type of calculations can be carried out inside Rhino if you know how to program in Python or VB. For myself I am writing custom scripts for various tasks. Once you have a detailed model, you can extract whatever information you need from it, hydrostatics, righting moments etc. I build my models in Rhino.Python parametrically, therefore it is very easy to change things and get instant feedback from the changes, both visual and analytical. If I'll ever find time I will also use some CFD Python libraries and implement some scripts to use them easier, but I have tons of stuff on the todo list. Rhino gives you access to powerful math solvers, and lightweight genetic algorithms, cool stuff that most people don't really use with a good purpose.
     
  5. DCockey
    Joined: Oct 2009
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    DCockey Senior Member

    I use DevSrf as well as Loft to create developable surfaces in Rhino. DevSrf is a free download from McNeel. http://wiki.mcneel.com/labs/devsrf It isn't mentioned in the promotional video for D.Loft.

    Based on the video D.Loft looks like it would be useful but not required to create good developable surfaces in Rhino. The promotional video is somewhat overdone in terms of making the Loft command look bad.
     
  6. TANSL
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    TANSL Senior Member

    isvflorin, I wonder, without analyzing much your job, what improves your program utilities that already has Rhino.
    The seas are full of boats with bow bulbs created by NO developable surfaces.
    Surfaces with two curves are NO developable, so I do not see what your bulbous bow provides shipbuilding.
    It may be appropriate to clarify that a "smooth" hull is composed of several patches of surfaces which, at the edges of contact, not only have equal tangents, but their curvatures (second derivatives). Your bulbous bow is, you forgive the expression, a "horror" speaking in terms of shipbuilding. I think you're trying to create a useful tool for shipbuilding, and that effort is much appreciated. But for now, you have not found the solution.
     
  7. isvflorin
    Joined: Nov 2009
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    isvflorin Junior Member

    Hi guys,
    many thanks for the feedback. I will try to be brief. There is much to know about developable surfaces, but I will not go into discrete differential geometry now. I know about Lowell plugin and have personally talked to him. It might be sufficient for some but it is limited and does not do any real geometry optimization (numerical optimization), the limitations are not really something you see with your eyes until you compare results from both plugins. It is not "my software" , just the software the company I work for puts out. I am not a core developer, I only do VB and Python programming. The tool does not want to be more than it is, it simply creates developable surfaces based on actual mathematical properties and numerical optimization, it is not naval software in itself, just fills a gap in the Rhino functionality. If anyone here claims the loft command from Rhino (with the "developable" style) is not too bad, I am not saying this to be rude or arrogant, but they don't have enough experience in 3d modelling, geometry and Rhino. Furthermore, as I explain in the video, it was a very simple example, in freeform architecture you will find way crazier shapes and examples were Rhino will fail in creating dev surfaces by itself. So please don't expect more than it is , just a simple command to make accurate dev. surfaces.

    Regarding the bulbous bow - as I said, it is an example of surface discretization with developable strips, and I understand your concerns. I believe it is mistaken as a "solution" to shipbuilding, it is not. It is a solution to discretizing double curved shapes with single curved strips, where ever they are needed, naval, architecture, product design, artwork. And yes, maybe we should be more clear about that on the website.

    The OP's thread asked for "developable surfaces", therefore I thought I'd add an option for people to know.
    To expand on the + and - of Rhino vs d.loft lofting - Rhino's loft produces polysurfaces, sometimes many of them, long thin ones, once you unroll those flat, you are presented with a big puzzle of long thin strips to assemble butt to butt, good luck with that. D.loft produces single surfaces each time, no worries about unrolling. Rhino fails in very simple examples due to its lofting approach. I would say these are the 2 major downsides. I believe what Evolute did can be considered significant "improvement".

    Well, this was not brief, sorry...
    Cheers,
    Florin
     
  8. DCockey
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    DCockey Senior Member

    The Rhino UnrollSrf command unrolls polysurfaces as a single flat polysurface, not individual separate pieces, unless the Explode option is set to Yes.

    So no need to worry about unrolling polysurfaces as long as the Explode option is set to No in UnrollSrf.
     
  9. DCockey
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    DCockey Senior Member

    DevSrf ("Lowell plugin") produces single developable surfaces, not polysurfaces. It gives the user with control of the ruling line density which is usually a tradeoff between surface complexity and how close the edges of the resulting surface are to the edge curves. It provides interactive visual feedback on the amount of twist in the surface. In many cases it does require extending the edge curves (simple to do with the Extend command) and subsequent trimming of the resulting surface. The shape of developable surface can vary depending on the shape of the extended edge curves as in reality. DevSrf can require in selecting the locations to pick the edge curves to produce good results some care and sometimes several attempts are needed to find good locations. DevSrf is free and available as a simple download from McNeel, the Rhino developers. http://wiki.mcneel.com/labs/devsrf

    The deviation between the edges of a developable surface and the input edge curves can be readily checked using the CrvDeviation command in Rhino.

    D.Loft from Evolute appears to be a convenient way to get good developable surfaces quickly in Rhino. It allows specification of the maximum deviation between the edges of the resulting developable surface and the input edge curves. Presumably this affects the complexity of the resulting surface. I don't see any thing on the amount of twist. D.Loft automatically extends the edge curves and then trims the resulting surfaces. There doesn't appear to be any control available of the shape of the extended edge curves.
     
  10. isvflorin
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    isvflorin Junior Member

    David,
    indeed I stand corrected on the explode option, however I doesn't make it much better, except the assembly of course. What if you want to extend that surface you got ? You just can't. Your option is to explode and extend all those tiny thin strips.

    I think you comparison description is as accurately as possible and if the free tool works for you and others I'm really happy about it.
    What if you have thousands of curves to loft ? Is the manual process any good ? That process is just a trial and error process, not a mathematically precise deterministic method.

    Also, with single curved surfaces, there is no such thing as "surface complexity", on the other hand we can refer to it as the UV parametrization density (the amount of rulings).

    D.loft optimizes a surface for 3 things - developability(twist minimization), fairness and closeness to curves. The least important is the closeness. If you work within document tolerance and there is no mathematical solution within that tolerance, you have the option to reduce closeness or allow twist. These will just pop up in the command bar for user input if no solution is found under the desired tolerance (curve closeness).

    I do realize I was a bit hasty to bash Rhino's options, but this is due to the amount of the failure rate in producing good single curved surfaces. Would you consider d.loft an improvement or not ?
    Cheers,
    F
     
  11. pdmsvn
    Joined: Jun 2014
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    pdmsvn Junior Member

    In my opinion, Napa software can help modeling 3d and get any section from model exactly, maybe I could help.
     

  12. aleutka29
    Joined: Aug 2008
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    aleutka29 Junior Member

    Create your model in MultiSurf using developable surfaces. The construction jig could be part of your model. When the hull is updated all your construction entities in the kit would update as well. The flat patterns could be out put to .dxf using MS-DEV.
     
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