basty Posted January 19, 2015 Share Posted January 19, 2015 I made a AB line and BC spline, connecting them at point B. I select these two, the line and the spline, and appears and equal curvature option. What this equal curvature mean? Quote Link to comment Share on other sites More sharing options...
lrm Posted January 20, 2015 Share Posted January 20, 2015 Curvature in this context is the instantaneous radius of curvature which you can think of as trying to represent a very small portion of a curve with an arc of equal radius. A tight curve has a small curvature and a gradual curve a large curvature. The curvature is infinite for a straight line or where a curve switches directions like halfway through an "S" curve (known as an inflection point). I do not know how you got this prompt to appear but you are being asked if you want the radius of curvature for line AB at B to be modified so that it is the same as the radius of curvature for spline BC at B. Splines are represented in the database as a series of Control Vertices or CVs. When creating a spline you can use Fit Points or CVs. If the second from the end CV for two end-to-end touching splines are the same distance from the end and lie on a line through the junction then the curvatures of the two splines are the same at the junction. In the pictures below you can see the Fit Points and CVs of two splines that do not blend at their meeting point. In the third image I have moved the second from the end CV to a point equal distance from the junction for both splines. I added the circle and line to highlight the position of the CVs. The curvature at the end is defined by the distance from the spline's end to the next CV. The slope is also defined by these two points. Quote Link to comment Share on other sites More sharing options...
SEANT Posted January 21, 2015 Share Posted January 21, 2015 . . . .In the third image I have moved the second from the end CV to a point equal distance from the junction for both splines. I added the circle and line to highlight the position of the CVs. The curvature at the end is defined by the distance from the spline's end to the next CV. The slope is also defined by these two points. An equal and aligned vector between the first/last two CVs defines C1 continuity (Tangency). Curvature Continuity (G2 or C2) depends on a third CV. Quote Link to comment Share on other sites More sharing options...
lrm Posted January 21, 2015 Share Posted January 21, 2015 Yes, you are correct. First two CVs for slope continuity, first three for curvature. Quote Link to comment Share on other sites More sharing options...
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