Circle Resolution

edited September 2016 in General

Hello Matthias,

This is regarding "Circle Resolution" that is the number of points "N" per full circle.

In the present implementation, this value is one of the user defined settings.

In LoadLayoutOptions class, this value can be set by ".dxf_circle_points=".

In most cases, this is fine.

However, in some cases, designs in DXF contain very small (less than 1 mm-dia.) circles
and very large (nearly 300 mm-dia) circles together.

To approximate such a big circle with tolerable errors, we need a big "N" but
it is then too big for approximating a small circle.

In this connection what to you think of having one additional user defined parameter "E(psilon) [um] or [DBU]" that
dynamically defines

"N" depending on the radius "R" of a circle or an arc being approximated.

Where, "E" is tolerable (maximum) gap between an arc and its chord.

If a circle whose radius is "R" is approximated by an inscribed regular-N polygon,

E = R - R*cos(pi/N)

Hence, N is a function of (E, R).
It may be preferable that "N" be an integral multiple of four (4).

If "N > 0" is specified, the conventional method is used.

If and only if "N == 0", "E" and the new method take effect.

This is my idea.

With best regards,



  • edited November -1

    Hi Kazzz,

    thanks for mentioning this issue. I understand the motivation for that. It is not a big issue for circles.

    But I guess there is a similar topic for all the other "smooth" features like splines, ellipses, arcs and so forth. I don't have a simple formula at hand for those.

    I'll take a look into that.



  • edited November -1

    Hi Matthias,

    Thank you for prompt response.
    To be frank, only circle and arc were in my mind!
    Your point is right.


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