Figure ground reversal

This came in from support difficulty in getting a purchased image:

to cut as desired.

We will review the specifics here.

First, we arrange things so that they are more easily seen:

Then we assign a simple V carving:

which previews as expected:

but is arguably exactly reversed — the sword and other heraldic elements are incised rather than standing proud.

We can get them to stand in bas relief by adding geometry around them and using Advanced V carving and pocket clearing:

which when added to the selection and assigned an Advanced V carving toolpath:

previews as:

which is closer, but we want the shield to show as a flat surface — that can be achieved in one of two ways:

  • delete one of the lines which defines it:

  • or add an additional line by insetting one:

and adding that to the geometry used for the V carving:

Similarly, other regions which become large pockets may be changed to detail highlights by selecting them and insetting them and adding the offset geometry to the selection:

If you wished to emphasize the design further you could offset it:

Ensuring that the gaps around the helmet were closed:

and delete the odd interior pieces:

and then assign a decorative cutting:

(probably one would need to inset the outer border as well)

Or, if one wished, one could use the geometry and just cut things out:

insetting by half the off-set distance to make the cut:

so that it is at the bottom of the V groove:

and offsetting by endmill diameter plus 10% so as to be able to cut as a pocket down to tab height or the penultimate pass:

with a Contour toolpath with tabs:

to finish the cut:


That’s quite involved.
I was curious about the offset being used around the sword handles and blades. In the original image, the swords lay on top of the wreath, but in the final simulation, the swords look like they are part of the wreath?

Again, figure-ground-reversal.

It’s all a function of what is drawn how and treated in what fashion.

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