# Should the cuvature graph edges align in these conditions?

Hello all,

Here is a picture of 3curves (degree 5 - 6CP) meeting at 0.
Before moving on to building the surfaces I wanted to ensure the qual ot theses curves.
The second point of each of these curves and their intersection are co-planar (ie point 0,1,2 and 3).

For some reason, I was expecting the curvature graph “edge” curves to be aligned as a result of the coplanarity of the CPs.
Am I mistaken ?
This is a step toward creating conditions for tangency continuity from surface between these curves. And before this want to fix the curves.

Curves.3dm (63.0 KB)

Thanks, Jean

Hi Jean,

The curves all finish at a end tangent angle of 0° to the CPlane in the file. However, the curve graphs are a bit “tilted” with respect to the Z-Axis of the CPlane, which is why they don’t line up vertically… Have a look in Plan view of your custom CPlane. I don’t know how this “tilt” is calculated, though…

–Mitch

Merci, Mitch !
So, How would you then adjust these curves to get the appropriate curvature graphs before surfacing ?
Here is a variant of the same with
i. Isocurves from surface extracted:

ii. These same isocurves displayed right off the surface.

I find that in several instances, surfacing from the curves (sweep2) without any tangency or curvature continuity yields the most predictable results. Then a matchsrf can fine tune the resulting surfaces and provide the required final surf continuity.
However, this would require being able to rework the curvature of the green curves for example… Is it possible to force a view so their are aligned like for the “surface” view ?

Thx, Jean P.

Hi Jean - the direction of the graph depends on the ‘plane’ of a curve there as well as the co-planarity of the second points. -

-Pascal