Hi Pilou, yes that's normal that a blend curve is not exactly the same as a circular arc, is that what you are asking about?

A blend is a general spline curve, not a conic section, it can even get constructed as an S type shape completely and totally different in shape than an arc, like this:



Blend is meant to be more like a flexible bendy type thing that can smoothly connect any type of pieces, it's not meant to only generate an exact arc shape. If you want to make an exact arc, you should use one of the arc drawing tools for making that instead of Blend.

- Michael

Thinks for the Info
I had believed the the default regulate was on the same result than an Arc-Circle for 2 segments at 90° mirrored by a bisector
So don't use it when you make a reconstruction!
So it's more artistic in this case :)

In the case above we can use a conic with a Rho of 0.41421... :)
More prudent is the Arc Cont :)

Frenchy, the difference is not just artistic. The main difference is curvature continuity. The tangent arc show an abrupt change of curvature where it neets the line. When this is translated to surfaces and rendered, there is a distinct visual line at the meeting point. This is called G1 tangent continuity. To avoid that artifact, G2 or G2 curvature continuity is needed. That's what the blend does. The curvature along the blend is not continuous as it goes from 0 to 0 at either end, and does it smoothly. This is the sort of continuity you need for surfacing things like a car body or the back of an I-Pad (Jason Ive, the designer at Apple, forbids the use of G1 anywhere in an Apple product).

< (Jason Ive, the designer at Apple, forbids the use of G1 anywhere in an Apple product).
Tyranny of the curvature ! :)