On Mon, Jul 15, 2013 at 11:44 PM, phoenix <[email protected]> wrote:
> Hi!
>
> After several weeks' work on the surface-surface intersections, it's
> improved significantly and can handle lots of cases that cannot be handled
> well before. It's more accurate and correct, ready for the evaluation.
> (Other intersections such as curve-curve, curve-surface, point-point,
> point-curve, and point-surface are also ready.) I'll still perform tests
> with some real geometries, such as the ones in db/*.g.
>
Am I correct that your tests so far have not needed to track the fuzzy
uncertainties involved with propagating "error bars" through multiple
intersections? Let's say, for example, that two curves intersect at a
point, within some tolerance. However, if we test both of those curves and
that intersection point against a surface, one curve intersects the surface
within tolerance, one does not, and the point does. What do we do?
I'm assuming that's what things like the connectivity graph are intended to
handle? I expect the papers on "robust" intersections probably also deal
with ways to address that problem, but once the shared surface case of
individual intersections is handled (obviously that's needed first) I think
this is doing to be the last critical piece for robustness - it's a major
source of grief for our NMG code (if I understand the problem correctly)
and having the Brep topology available to add more information into the mix
should be a big help. I know that's not on the schedule until August, but
now that the individual intersections are looking good and we're starting
to think about robustness that is setting the stage for the handling of
cumulative intersection operations.
Cheers,
CY
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