kicad-developers team mailing list archive

[R P Herrold <herrold@xxxxxxxxxxxx>]

On Tue, 10 Dec 2013, Rick Walker wrote:

> > Is this an artefact of some setting (gerber file perhaps) or is
> > it a math rounding error internally, or something else?
 
> Vendors often uses a design rule checking program optimized 
> for speed. To achieve this they often approximate pads as 
> octagons.  Of course an octagon is smaller than a perfect 
> circle.  In fact, any non-infinite sided approximation will 
> be smaller across the facets than a true circle.

To continue with your example, it would seem that using an 
octogon that hits the circle on the (interior) flats of a 
bounding octogon (or higher 2^N polygon) would always be 
'safe', and is an obvious way to avoid infringements.  If one 
is 'tight' on space, note 'hotspots' to optimize, increase the 
N and accept the time penalty

Is this not done?

-- Russ herrold