Hi Nyall On Fri, Jul 26, 2019 at 4:40 AM Nyall Dawson <[email protected]> wrote: > > Hey lists > > This was first discussed back in 2016 (see > http://osgeo-org.1560.x6.nabble.com/Removal-of-labeling-search-methods-td5262743.html), > but would anyone object if the different labeling solution algorithms > eg "chain" / "pop music" / "falp" / etc were dropped, and we just > leave the existing default (chain)?
As stated in the earlier email, I would not mind if we remove those. Are you thinking about removing the option in GUI or to get rid of the code in PAL for other methods too? > I don't think ANYONE knows what these mean, and it's a heck of a lot > of code (which needs fixes) to cart around for no compelling reason > that I can see. > > I have no particular preference to any of the methods, so would > happily accept a different default if anyone out there can point to > which method is best! > > Googling pop music / tabu / chain only gives a handful of results > relating to QGIS labeling engine. And googling for "falp" sounds like > something that would get you flagged on your company's firewall. To shed some light on the methods for those interested... a good starting point is PAL docs [1] with links to papers, unfortunately most links there are broken, but this paper is a good start: Laurent et al: From Point Feature Label Placement to Map Labelling (2009) The paper is available here [2] and gives an overview of the whole process of labeling with PAL. Generally the idea is to turn labeling into a general combinatoric problem and then apply some heuristic. The paper also covers the various optimization techniques. FALP seems to be the most basic initial solution. "Tabu" seems to be a meta-heuristic method from 1980's [3], "chain" stands for "ejection chains" concept somehow related to Tabu search. And finally Popmusic is a search method co-authored from one of the authors of PAL. I remember there was a paper with quite extensive testing of the methods, but can't find it anymore. From what I remember, one would higher amount of labeled features with a slower method (e.g. Popmusic) or fewer labels with a faster method. If we decide to stick with a single method, it may be interesting to get the opinion of original PAL authors on what method to choose... I don't know enough about those methods to decide. Cheers Martin [1] http://pal.heig-vd.ch/index.php?page=support [2] http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.472.4491&rep=rep1&type=pdf [3] https://en.wikipedia.org/wiki/Tabu_search _______________________________________________ QGIS-Developer mailing list [email protected] List info: https://lists.osgeo.org/mailman/listinfo/qgis-developer Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-developer
