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Subject: Re: [geometry] Bug again in boost::geometry::union_
From: Barend Gehrels (barend_at_[hidden])
Date: 2014-02-12 10:09:37

Hi Sybren,

Sybren A. Stüvel wrote On 12-2-2014 15:10:
> Hi Barend,
> On 12 February 2014 13:46, Barend Gehrels <barend_at_[hidden]
> <mailto:barend_at_[hidden]>> wrote:
> Good. That warning can be ignored. It's a (more or less personal)
> development branch. Please comment it in cart_intersect.hpp if you
> want to get rid of it. I will fix this but it is, for me,
> diagnostic information
> I suspected as much. Didn't want to keep any diagnostic info to myself ;-)
> Ah, that is a known problematic side-effect. That has to be fixed
> too but of course, if you need it today, or even somewhere this
> week, I cannot do that.
> Alas, then I'll have to wait a bit more.
> You can try one more thing: please define
> BOOST_GEOMETRY_NO_ROBUSTNESS. It will than skip all
> rescaling-to-integer-for-robustness code. That sounds a bit weird,
> because this thread was to fix that. But besides the rescaling
> more enhancements have been made, so it might be that your code
> then runs OK. However, I cannot predict that, there are also cases
> which really need this rescaling. So you can try how it looks.
> Unfortunately, that doesn't help. Then I get an empty result at some
> point - see the attached "exception.svg" file.
> Besides that, maybe even better, you can try to call the function
> "geometry::remove_spikes" on your output. It hopefully will remove
> all spikes which are generated.
> It appears that it doesn't, the spike is still there. I tried this
> without defining BOOST_GEOMETRY_NO_ROBUSTNESS, as the empty result I
> described occurs sooner than the generation of any spike.

That is right.

> Finally, could you also send me the WKT's of your input, for me to
> check that generated internal spike (as we call it)?
> I have attached the two inputs (poly0/1) and the result that I get
> from the union.

Thanks for the info and files. OK, so alas that spike is there for some
time, sorry for the inconvenience. I will mail if this is fixed.

Regards, Barend

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