Hi Gerd Sorry about the delay in replying. I think the solution needs to be along the lines of the way largeObjectArea creates addition subdivisions, but with changed rules, and replacing largeObjectArea and !useNormalSplit logic. Is there an existing problem with largeObjectArea? Some thoughts on how it might work: 1/ much more accurate MapArea.getEstimatedSizes, that takes into account zoom dependent filtering as best as is feasible. 2/ MapSplitter.addAreasToList stops attempting to split an area in half once its size is less than quite a few pixels at the zoom level. Instead it passes a new flag to MapArea.split (or even a new routine) 3/ If this flag is set: have ArrayList of areas and usedSize. estimate size of item to be added (with 1/). add to first area that it will fit into. If none, create another. This will also improve behaviour for low resolution (esp. overview) maps where excess splitting takes place because it considers the data usage at res 2. At the actual resolution, the number of points in a shape/line might be vastly reduced. Ticker On Mon, 2017-01-16 at 15:48 +0000, Gerd Petermann wrote:
Hi Ticker,
(see 3756) the useNormalSplit code is still needed, maybe because the rules for the largeObjectAreas are not okay. So if you find a better solution please let me know. I am also no longer convinced that the code in MapSplitter which sets wantSplit to true is a good idea, esp. in combination with --order-by-decreasing-area I guess it would be better to avoid unnessary splits. Am i right?
Gerd
________________________________________ Von: mkgmap-dev <mkgmap-dev-bounces@lists.mkgmap.org.uk> im Auftrag von Gerd Petermann <GPetermann_muenchen@hotmail.com> Gesendet: Sonntag, 15. Januar 2017 15:10:48 An: Development list for mkgmap Betreff: Re: [mkgmap-dev] [Patch] "Area too small to split at " ... followed by "Too many POIs at location " error message
Hi Ticker,
the original intention of the useNormalSplit code was to solve a problem with two huge polygons having the same center point. At that time I tried to minimize the possibility that this code is executed in other cases. However, it seems that this is dead code since r3351 because of the handling with largeObjectAreas. I think I should remove it.
Gerd
________________________________________ Von: mkgmap-dev <mkgmap-dev-bounces@lists.mkgmap.org.uk> im Auftrag von Ticker Berkin <rwb-mkgmap@jagit.co.uk> Gesendet: Sonntag, 15. Januar 2017 14:41:27 An: mkgmap-dev@lists.mkgmap.org.uk Betreff: Re: [mkgmap-dev] [Patch] "Area too small to split at " ... followed by "Too many POIs at location " error message
Hi Gerd
Yes; however, regardless of useNormalSplit, with --order-by... the shapes need to be split into their correct area.
This bit of code has always troubled me. I wasn't sure if its objective was to lessen the chance of empty subdivisions or to lessen the chance of exceeding maximum data sizes in the subdivision.
Maybe splitIntoAreas (and, for that matter, points) shouldn't set used[area] to true so that lines can be distributed between the two areas.
Also the test ... && (this.lines.size() > 1 || this.shapes.size() > 1)) should take ((lines.size + shapes.size) > 1). But not including shapes if --order-by...
Another possibility is that the caller of MapArea.split, with accurate information on the number/size of subdivision data items, knowing that this is more that will fit into a subDivision and further splits by area are not possible, passes a flag that make it send excess items into other subdivisions - very much like the way it handles largeObjectAreas
Ticker
On Sun, 2017-01-15 at 10:00 +0000, Gerd Petermann wrote:
Hi all,
attached is a patch to solve this problem.
A binary is here: http://files.mkgmap.org.uk/download/327/mkgmap.jar
@Ticker: Please review. I've noticed that with --order-by-decreasing-area the code in MapArea to set useNormalSplit may not be used because the condition used[0] != used[1] is never true when there is a shape in that area. I think this can cause problems if we also have some complex lines with (nearly) the same center point in the same area.
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