[geos-devel] TopologyException makes GEOS/JTS very difficult to employ in my production environments...

Howard Butler hobu.inc at gmail.com
Wed Sep 29 10:44:28 EDT 2010

On Sep 29, 2010, at 8:31 AM, G. Allegri wrote:
> I anticipate the critics: put the money on the table and someone could
> invest time to solve it. Holy words, this is how foss should work. But
> I'm not the boss of my company, and I've suggested to employ
> PostGIS->GEOS in a big job... and now I have to solve this issue, with
> no extra-money.
> If this problem cannot be solved I have to abandon PostGIS for one of
> our production environments, and that would be a pity.

Your choices are:

- Put the time in and fix the bugs yourself
- Put the money in and attract experts to fix the bugs
- Find an alternative and implement it

Saying that it's a pity you can't use software XX because the bugs *you* need fixed are not being fixed by someone else at no cost is not an option.  First, no one cares.  Second, the social contract of open source software requires that you put the time and money into getting what you need out of it.  Emails like this are not helpful to your cause, and in fact they will act to paint you as someone not being worthy of helping.

What if putting the amount of money you would have to pay for the commercial solution toward the bug fixes you need solved the problem?  I don't know that it would be enough to actually solve your issues, but if you did that, I think you would still be further ahead than if you used the commercial solution.  You need to express the issue(s) to your boss in these terms.  

> So, my reflection is: in a few weeks we have fighted, almost daily,
> with this error. Are we the only ones to get stuck in it? Have others
> found consistent,deterministic solutions?

One way to eliminate a number of the topology issues might be to re-implement PostGIS with a computational geometry library that uses math that doesn't have floating point precision issues.  LEDA and CGAL come to mind.  Neither of these libraries directly map very well to the specific problems of geographic geometry problems, however, and implementing either would bring significant licensing challenges (you're going to have to pay).  The cost to do this work would be huge as well.

If the vast majority of PostGIS/GEOS users frequently had these problems, they would either be fixed or no one would use PostGIS/GEOS...


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