[mkgmap-dev] nearby-POI: What to do with several POI arranged on a circle?From Gerd Petermann gpetermann_muenchen at hotmail.com on Fri May 8 05:27:33 BST 2020
Hi Mike, reg. 1 + 2: I thought the "POI within area" can be ignored here, we have the is_in style function to catch that? reg. 3: merge-at-mid-point is likely to cause trouble. Let's remove it for now, seems nobody really needs it. Gerd ________________________________________ Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von Mike Baggaley <mike at tvage.co.uk> Gesendet: Donnerstag, 7. Mai 2020 20:58 An: mkgmap-dev at lists.mkgmap.org.uk Betreff: Re: [mkgmap-dev] nearby-POI: What to do with several POI arranged on a circle? I had a few more thoughts on the multiple POI case. There seem to be three scenarios that possibly need handling in different ways: 1. a cluster of POIS that are incorrectly tagged (e.g. every building in a college is tagged as amenity=college). In this case if there are more than 2 POIS I would ideally like a higher severity level of message to be used so that I can easily identify the problem and fix it in OSM. 2. a cluster of POIS that are correctly tagged, but I don't need to see every one (e.g. bus stops within a bus station). In this case I would like to reduce the bus stops to a single one (or even better if there is a bus station tagged, remove all the bus stops). 3. a cluster of tags where I am happy to see several of them, but don't necessarily need them all (e.g. with park benches it is useful to see there are several, but it's not necessary to see every individual seat). Regarding the position algorithm, I suggest the merge-at-mid-point option only operates when there are two POIS. With multiple POIS just choose the nearest POI to the centre and delete the others for both delete-poi and merge-at-mid-point. That would solve any problems of it ending up in the middle of a lake when used on objects surrounding the lake. Or we could just drop merge-at-mid-point if it is too tricky to come up with something that doesn't have unwanted side effects. Regards, Mike -----Original Message----- From: Mike Baggaley [mailto:mike at tvage.co.uk] Sent: 07 May 2020 16:10 To: 'mkgmap-dev at lists.mkgmap.org.uk' <mkgmap-dev at lists.mkgmap.org.uk> Subject: RE: [mkgmap-dev] nearby-POI: What to do with several POI arranged on a circle? Hi Gerd, finally managed to try your updated code and it looks like a great improvement over my starting point, which whilst it did work in some places, in others it seemed to have no effect. The barrage of extra deletions also pointed me to a problem in my points file which was creating a POI to display the name of power generators without any icon. Originally this just showed big generators, but as there are now lots of solar panels on people's houses mapped it has been adding thousands of POIS with no icon and no name, which wasn't a great deal of use! Regarding the multiple POI case, it really depends on what type of POI it is. The logs pointed me to a tourist destination where every holiday home had been tagged as a hotel - for that one I would ideally want just a single point left, and preferably the severity of the message increased, so that it is easy to pick out and go and fix at source. For ones like a line of park benches, I'd be perfectly happy with them only being considered in pairs (just thinning the POIs so that you can still see there are plenty of seats). Regards, Mike -----Original Message----- From: Gerd Petermann [mailto:gpetermann_muenchen at hotmail.com] Sent: 07 May 2020 15:04 To: mkgmap-dev at lists.mkgmap.org.uk Subject: Re: [mkgmap-dev] nearby-POI: What to do with several POI arranged on a circle? Hi Randolph, I try to find out what the result should be when more than two POI are involved. They may be arranged in a straight line or in a circle or whatever random order. At the moment I tend to follow Tickers suggestion and remove the option to keep it simple. Gerd ________________________________________ Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von Randolph J. Herber <army.bronze.star at gmail.com> Gesendet: Donnerstag, 7. Mai 2020 15:21 An: mkgmap-dev at lists.mkgmap.org.uk Betreff: Re: [mkgmap-dev] nearby-POI: What to do with several POI arranged on a circle? Perhaps averaging the latitude and longitude coordinates of all the points separately would work. That is not quite the same as meet in the middle. If the points are evenly spaced around the edge of a circle, even though the latitude and longitude scalings (except at the equator) are not the same. What I believe you are trying to do is minimize the total distance from the selected point to the collection of points. Randolph J. Herber On 5/7/2020 2:42 AM, Gerd Petermann wrote: Hi all, while doing further tests I've found this edge case (see attached file) Draw a circle with a diameter of ~56m and tag all nodes amenity=bank. The default style has amenity=bank [0x2f06 resolution 24] With --nearby-poi-rules=0x2f06:30:merge-at-mid-point one might expect a single POI in the middle of the circle, but the result is different: Since there is no POI near the center of the circle the current algo finds 4 groups, all close to the edge of the circle. I think for merge-at-mid-point I need a different algo. I'm looking at https://en.wikipedia.org/wiki/Cluster_analysis now. Gerd _______________________________________________ mkgmap-dev mailing list mkgmap-dev at lists.mkgmap.org.uk<mailto:mkgmap-dev at lists.mkgmap.org.uk> http://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev _______________________________________________ mkgmap-dev mailing list mkgmap-dev at lists.mkgmap.org.uk http://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev
- Previous message: [mkgmap-dev] nearby-POI: What to do with several POI arranged on a circle?
- Next message: [mkgmap-dev] nearby-POI: named / unnamed
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
More information about the mkgmap-dev mailing list