On Sat, 15 Oct 2011 08:53:45 +0000 (UTC) Martin Spott <martin.sp...@mgras.net> wrote: > I think the only solution is to make GPC obsolete - either by replacing > GPC by something different but functional equivalent or "simply" (TM ;-) > by avoiding any polygon clipping in 'fgfs-construct' overall.
For what it's worth... I am currently trying to generate custom scenery for all of Europe based on Corine + OSM data (similar to what I did for France some time ago: http://wiki.flightgear.org/Custom_France_Scenery), and I am also getting lost in the intricacies of fgfs-construct and crashes in GPC. I managed to make a few changes in the code that improved the situation: - conversely to what is suggested in README.gpc, I did not change the GPC_EPSILON constant (left it defined as DBL_EPSILON) - I completely disabled the removal of so-called "bad nodes" in poly_support.cxx However I did a lot of preprocessing of the data in Postgis before feeding it to fgfs-construct, hopefully removing the need for the hacks mentioned above. So far this configuration has proved very stable for me, and I was able to generate more than a hundred of 1x1 deg tiles without any crash. So far the only problems that remain seem to be located around the 0deg longitude area - there, I am still running into the problem of the NULL pointer in the GPC merge_right(). What I noticed so far lends me to think that there is a lot of code in terragear that is supposed to deal with imperfect input data - and should maybe be deactivated. Can anyone shed some light on what the "bad node" detection is supposed to achieve, for instance ? Also, the suggested increase of GPC_EPSILON is bound to introduce inconsistencies in the geometric routines - much better to clean up the input data). Unfortunately, there are many places in terragear where some arbitrary "epsilon" constants are hiding with unexpected effects - just run "grep -r '0\.0000' terragear-cs" and count the matches if you don't believe me. So maybe the problem is not in GPC after all but in what we feed it.... Maxime ------------------------------------------------------------------------------ All the data continuously generated in your IT infrastructure contains a definitive record of customers, application performance, security threats, fraudulent activity and more. Splunk takes this data and makes sense of it. Business sense. IT sense. Common sense. http://p.sf.net/sfu/splunk-d2d-oct _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
