Explicit modeling is a technique in which the surfaces and curves are modified by modifying the CVs and hulls explicitly and without any history. The move CV tool in the control panel enables the movement of CVs and Hull in different ways .. XYZ mode where the movement is restricted to the XYZ axis, Slide mode where the movement is restricted along the hull directions, NUV mode where the movement is restricted to the Normal, U parameter and V parameter (in case of surfaces) and project mode in which the movement is restricted to the hull direction including that of any external geometry. The following figure shows a small example of explicit modeling to align a curve to another.
Fig 1 shows two curves of degree 2 with their curvature comb and touching each other. The curvature comb indicates that the curves are touching each other much not tangent.
Fig 2 shows use of Move CV > Project . The curve is now tangent to each other. As the mouse id dragged the tangent scle of the curve changes.
Fig 3 shows use of Move CV > XYZ .The third CV is moved in such a way that the curvature plots touch each other. Further checks such as Surface continuity or curve continuity can be used to confirm that necessary tolerance was achieved.
Fig 4 shows the use of Move CV > Project with parallel option switched on. The third CV is moved parallel to the first hull direction. This will change the curvature scale. The CV can be dragged till a satisfactory curvature plot is obtained.
This method can be extended to explicitly model surfaces too.
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