Again about hull shape modeling…

Discussion in 'Software' started by Alexanov, Jun 16, 2021.

  1. Alexanov
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    Alexanov Senior Member

  2. TANSL
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    TANSL Senior Member

    Read in your article : "Hull shape is a visual art object, and it is good to have possibility for make it as you want, but not like your software can."
    That is a great truth and how few people take it into account and value it!. We are used to seeing that the one who designs is the computer.
    Congratulations on your work.
     
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  3. Alexanov
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    Alexanov Senior Member

    Thank you! It is what I try to explain for software users: “If you think you can model the surface of a ship's hull in half an hour, you are probably new to this business. But if you know what to do, then it is realistic to get a smoothed surface of the ship's hull in about a week. I've been doing this for too long to believe that some fantastic program can do it quickly and, most importantly, in the way that a designer needs.”
     
  4. pafurijaz
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    pafurijaz Senior Member

    I'm involved in the latest months on this, I'm studying the G2 continuity on patches for Nurbs and subdivision both has the same rules, substantially subdivision is a bicubic patch and the control cage is the same like Bezier surfaces but with it is very complex reach the G2 tangent curvature continuity with complex shapes.
     
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  5. DCockey
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    DCockey Senior Member

    From the second paragraph of the link in the first post ( https://www.shmexpert.com/post/five-stages-of-fore-body-smoothing-by-one-surface-patch ) in reference to modeling the forebody of a hull with multiple surfaces:
    Is this claim specific to Shape Maker or for any surface modeling software?
    Is it being claimed that it is impossible to match curvature between any pairs of NURBS surfaces including untrimmed degree 3 surfaces? If so how is it done for "Class A" automotive surfaces?
     

  6. Alexanov
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    Alexanov Senior Member

    Of course, this is possible, but at the same time the boundary lines of the surface patches should already lie on the imaginary surface of the ship's hull. An imbalance between the boundary lines will give waves on the surface. So, if the boundaries of the surface patches are frames, very often the water lines at the intersection with the frames can have waviness. And it us quite difficult to control. If you talking about "Class A" surfaces, you have to use hight than 3 degrees for patches. With it your surface modification will not be so local. Not sure if we actually need double continuity in some areas of ship’s surface. Simple example - horizontal bottom surface and flat side rounded by bilge radius. It is only first derivation continuity.
     
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