[mkgmap-dev] [PATCH v2] - round coordinates when zoomed out

Sat Nov 21 19:42:26 GMT 2009

Can't notice any difference to v1.

BTW - Is it possible that there is a difference with the douglas peucker 
filter whether a road is routable or not?
I think it is possible that non routable ways are smoothed heftier than 
routable ways. This has nothing to do with this patch though, but the 
difference only seems to become really visible on resolution <20
(maybe resolution 24 is filtered if not routable, but not filtered if 
routable. Then the more filtering is applied on each successive level, 
the bigger the difference).

Also I noticed that cgpsmapper maps, seem to have much higher smoothing 
at lower resolutions compared to mkgmap (using 2.6). At resolution 24 
and 22 it seem to be mostly identical though. Maybe we could also 
increase the douglas peucker severity on resolution <20 compared to 
right now. Even with very few lines mkgmap maps seem slow on GPS on 
resolution 16 or 18.

Mark Burton wrote:
> v2 - also removes points with the same coordinates as the previous
> point. I know that this also gets done by the DP filter but it's very
> easy to do while rounding the coordinates and it does shrink the number
> of points to be processed by subsequent filters. This version of the
> patch should produce the same map as v1 of the patch.
>
> Unless anyone has any problems with this patch, I intend to commit it
> in a few days as I think the line gap-filling is worthwhile.
>
> -------
>
> Having filled some gaps with that last little patch, I was wondering
> why I still had quite a few gaps when zoomed out. Obviously, the coords
> weren't being rounded to nearest given the zoom level. So, the
> attached patch does that rounding and, lo and behold, even more gaps
> have disappeared. 
>
> Please give it a go, especially for maps that cross the equator/day
> line where the coords flip signs. Sure to be buggy but it's looking
> quite promising.
>
> BTW - this patch does not contain the last patch but they probably
> should be used together.
>
> Mark
>   
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