Hello.
TraceArcPath does not work well when you want to draw
an arc with a large radius. It might be good to add
a condition to convert such arcs to lines instead.
If arc goes from A to B with radius R, I propose the
following condition:
d = distance(A,B) / 2
if (d / R < 1e-4)
TraceLine(...)
For R >> d, d/R is approximately the angle between
the line AB and the tangent on the arc in point
A or B.
MagickEpsilon might also work instead of 1e-4.
Here I assumed that the arc is part of a circle. If
it is part of an ellipse an appropriate R' might
be needed.
Marko Mahnič
Example with ImageMagick 6.3.0-6 Q8 (it does not happen
with Q16; the cause for the ghosts might be a rounding
error).
You can see the ghost line crossing the arc.
convert -density 600 -size 800x800 xc:white -fill none
-stroke black
-strokewidth 2.4 -draw  largearc.pth ghost.png
--------- largearc.pth ---------------
path '
M500,409
L433,409
A535449000 535449000 203.738 0 1 431,410
L401,380
'
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