Hi Regina and others; This is an interesting suggestion. Basically, as a design principle I suppose one could argue that there's no point in throwing an exception unless there's a way to catch it. Just another way in which SQL lets us down...
I'm sure you're right; there appears to be no shortage of good people out there with GPSes and ArcView making furry data for the rest of us :-) I've had pretty good success with two approaches to getting rid of data lint. One is to use st_simplify() with a tolerance that's compatible with my data resolution. The other one that often works even better for me is st_snaptogrid(). You could probably convince yourself that Nyquist's sampling theorem would apply in this case, so that if your mapping process could not distinguish data points closer than X meters apart, then you should use X/2 as your tolerance for simplifying or snapping to a grid. Obe, Regina wrote: > I've been doing a lot of work using ST_Intersection, ST_Difference, > ST_Union etc to cut out slices of geometries I don't want and slicing > up geometries into smaller pieces, reunioning etc. > > I've been running into a lot of Topological Exceptions of the form > directed Edge this and non-noded that. For the most part I've been > able to overcome these by slicing things smaller or skipping over > problem regions (e.g. areas where the difference is a line or point or > something of that sort). > > I think a lot of people have run into the same issues and have gotten > frustrated and there doesn't seem to be a simple solution suggested to > overcome these. > > Is there any way we can change (add overloaded functions or some > setting parameter) - that take additional parameters to simply ignore > these errors that says return empty collection or NULL when a GEOS > error is thrown. That way I can simply ignore these and throw them > out of my equation and move on. > > Just a thought. I'm sure my suggestion is rather simple-minded and > I'm sure I'm missing some reason of why this is not feasible. An > explanation of why my suggestion is stupid at anyrate would be nice. > > Thanks, > Regina > ------------------------------------------------------------------------ > > *The substance of this message, including any attachments, may be > confidential, legally privileged and/or exempt from disclosure > pursuant to Massachusetts law. It is intended solely for the > addressee. If you received this in error, please contact the sender > and delete the material from any computer. * > > ------------------------------------------------------------------------ > > * Help make the earth a greener place. If at all possible resist > printing this email and join us in saving paper. * > > * * > > * * > > ------------------------------------------------------------------------ > > _______________________________________________ > postgis-users mailing list > [email protected] > http://postgis.refractions.net/mailman/listinfo/postgis-users > -- Regards, Chris Hermansen · mailto:[EMAIL PROTECTED] tel:+1.604.714.2878 · fax:+1.604.733.0631 Timberline Natural Resource Group · http://www.timberline.ca 401 · 958 West 8th Avenue · Vancouver BC · Canada · V5Z 1E5 C'est ma façon de parler. _______________________________________________ postgis-users mailing list [email protected] http://postgis.refractions.net/mailman/listinfo/postgis-users
