Rhino - exact curve through points is easy and quick

Discussion in 'Software' started by DCockey, May 19, 2020 at 10:17 PM.

  1. DCockey
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    DCockey Senior Member

    Incorrect claims have been made that it is very difficult in Rhino to create splines which pass directly through selected points.

    It is quick and easy in Rhino to create splines which pass directly through selected points. The InterpCrv command creates a NURBS curve which passes exactly through selected locations where the mouse is clicked. Osnaps can be used to assist with accurate placement of the mouse cursor. Knot spacing type can be uniform, square root of chord or chord. The curve degree is specified by the user and can range from degree 1 to degree 10. The tangent direction of the spline at either end can be specified by the use for curves of degree 3.
    Rhinoceros Help http://docs.mcneel.com/rhino/6/help/en-us/index.htm#commands/interpcrv.htm

    A second Rhino command to easily and quickly create splines which pass directly through points is CurveThroughPt with Type=Interpolated. The user selects a set of points and Rhino fits a spline through the points. Like InterpCrv the user can specify the curve degree and knot spacing type.
    Rhinoceros Help http://docs.mcneel.com/rhino/6/help/en-us/index.htm#commands/curvethroughpt.htm

    The Curve command in Rhino is used to create curves with selected control point locations.
    Rhinoceros Help http://docs.mcneel.com/rhino/6/help/en-us/index.htm#commands/curve.htm

    CurveThroughPt with Type=ControlPoint can be used to create curves with control points located coincident with a user selected set of points.

    The AutoCAD equivalent to Rhino command InterpCrv appears to be the AutoCAD Spline command using the Fit method. One difference is the degree in AutoCAD is fixed to degree 3. The The AutoCAD equivalent to Rhino command Curve appears to be the AutoCAD Spline command using the Control Point method.
    SPLINE (Command) | AutoCAD 2020 | Autodesk Knowledge Network https://knowledge.autodesk.com/support/autocad/learn-explore/caas/CloudHelp/cloudhelp/2020/ENU/AutoCAD-Core/files/GUID-5E7D51E2-1595-4E0C-85F8-2D7CBD166A08-htm.html
     
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  2. Ad Hoc
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    Ad Hoc Naval Architect

    Many thanks for this David...Most helpful - as always.
     
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  3. pafurijaz
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    pafurijaz Senior Member

    Of course you can go with a single spline and create a perfect copy of a curve, but what is complicated is the prediction of the generated surface, which will deviate greatly, only if you model a simple straight object can you easily predict how will be the surface, but if you have to make a complex curved surface the work will be done in various patches composed of simple surfaces. this is a problem that can be corrected later by moving the control points. this in my opinion is the point, and it also happens with Autocad, as long as you make tubes, simple extrusions, and lofts of two paths all perfect, but if you have to create complex elements the thing becomes complex, but still feasible if it splitting down and is edited in a secondly, this is because Rhino is has not the advanced tools for tangent type G1 G2 G3 but it can be done with some time. Working at precision levels for manufacturing at an industrial level other software is used, and it takes time. But that is related only when you have a specific constraint with dimensions. with V hull or simple one non problem.
     
    Last edited: May 20, 2020 at 6:37 AM
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  4. TANSL
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    TANSL Senior Member

    I am not going to argue with you anymore, but if you refer to me (if not, it does not matter), I will tell you that I have never talked about the difficulty of adjusting splines to a series of points but rather the difficulty of making pass surfaces exactly through the points that defined them.
    I have observed that very often you say that I have said things that I have not said. Well, if that's okay with you, try to correct that flaw.
     
  5. DCockey
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    DCockey Senior Member


  6. TANSL
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    TANSL Senior Member

    I do not have anything else to say, only that you read from time to time the comments of other members of this forum, in the thread that you have created yourself, to which you refer in your previous post. Please note that in addition to 7-meter boats, there are considerably more complicated hulls.
     
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