[mkgmap-dev] Subdivision width is 36627 at 3230916/1236133

Sun Apr 22 22:01:16 BST 2012

Hi,

I think the problem is not a polygon or something like this. 
MapSplitter contains a lot of tests to make sure that an area doesn't contain too many objects, but the test doesn't check for the case that the area is too large, so it skips the split process for a large almost empty area:
            if (area.getNumLines() > MAX_NUM_LINES ||
                area.getNumPoints() > MAX_NUM_POINTS ||
                (sizes[MapArea.POINT_KIND] +
                 sizes[MapArea.LINE_KIND] +
                 sizes[MapArea.SHAPE_KIND]) > MAX_RGN_SIZE ||
                sizes[MapArea.XT_POINT_KIND] > MAX_XT_POINTS_SIZE ||
                sizes[MapArea.XT_LINE_KIND] > MAX_XT_LINES_SIZE ||
                sizes[MapArea.XT_SHAPE_KIND] > MAX_XT_SHAPES_SIZE){
...
            }

            log.debug("adding area unsplit", ",has points" + area.hasPoints());

later, in MapBuilder, this part causes the warning message:
        int w = ((area.getWidth() + 1)/2 + mask) >> shift;
        if (w > 0x7fff) {
            log.warn("Subdivision width is " + w + " at " + new Coord(latitude, longitude));
            w = 0x7fff;
        }

I am not sure what kind of test we have to add in MapSplitter. 

Gerd

> Date: Sun, 22 Apr 2012 23:39:28 +0300
> From: marko.makela at iki.fi
> To: mkgmap-dev at lists.mkgmap.org.uk
> Subject: Re: [mkgmap-dev] Subdivision width is 36627 at 3230916/1236133
> 
> Hi WanMil,
> 
> >AFAIK 3230916/1236133 is only the center point of the problematic 
> >polygon. I thought that my commit r2028 has fixed problems where a 
> >single polygon is too big to fit into a subdivision. This is done by 
> >the class PolygonSubdivSizeSplitterFilter.
> 
> Could the diagnostics be extended to show more details of the polygon, 
> such as the WGS84 coordinates of some nodes (or the OSM id or tags, if 
> they are available)? I am happy to apply such a patch and rerun, and 
> narrow down the input if it is of any help. Currently, I am using mkgmap 
> r2272.
> 
> >The MapSplitter/MapArea class should be a good starting point to track 
> >down the problem.
> 
> I hope you or Gerd can figure this out. Sorry, my day job keeps me so 
> busy that I do not have any spare brain power for coding or debugging at 
> the moment.
> 
> Best regards,
> 
> 	Marko
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> mkgmap-dev at lists.mkgmap.org.uk
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