[mkgmap-dev] Problems with sea in overview map

Sat May 22 12:30:19 BST 2021

Hi Gerd

I've been doing experiments on tiles with much more sea and islands
(tests before only had a bit of sea and lots of city).

With my re-ordering I get a very slightly smaller main tile (4096 bytes
in 5614K) and larger osmmap.img (34304 vs. 25088)

In both cases I'm getting quite a few shapeSplitter messages where it
finds inconsistencies in the line directions across the split-line;
normally due to self-intersection. These are happening in both the main
tile generation and the overview combining.

Once shapeSplitter has generated this type of warning it is
indeterminate which is shape and which is hole, so I'd expect gaps in
the rendering. 

I think trunk had eradicated split/self-intersection problems in the
tile processing, including the ovm_ file generation.

I'm not sure about the overview combiner as, in my standard map-build,
I don't merge shapes. 

Ticker

On Fri, 2021-05-21 at 16:41 +0000, Gerd Petermann wrote:
> Hi Ticker,
> 
> I tried this patch with r4734 and I see no improvements. Maps are
> larger, more white rectangles in sea.
> 
> Maybe my recent changes don't work well with yours? Do you have an
> example where it improves something with r4734?
> 
> Gerd
> 
> ________________________________________
> Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag
> von Ticker Berkin <rwb-mkgmap at jagit.co.uk>
> Gesendet: Freitag, 21. Mai 2021 18:10
> An: Development list for mkgmap
> Betreff: Re: [mkgmap-dev] Problems with sea in overview map
> 
> Hi Gerd
> 
> I'd been doing some investigation of filters ordering (based on
> trunk).
> I'd also done the pre-filtering of lines & shapes by minRes.
> 
> My conclusions are:
> 
> Shapes:
> It is better to run SizeFilter after RemoveObsoleteFilter.
> It is more efficient to run DP filter after both of these.
> 
> Lines:
> LineSplitterFilter should be run after everything that can remove
> points.
> It is more efficient to run DP after RemoveObsoleteFilter.
> 
> I've adapted my changes into a patch for the low-res-opt branch,
> along
> with removal of some resolution tests that are now redundant.
> 
> For the contourFilters, I've left DP as the first filter but moved
> LineSplitter as for the normalFilters
> 
> Ticker
> 
> 
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