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[mkgmap-dev] DP Filter and areas at Resolution=24

From Thilo Hannemann thannema at gmx.de on Thu Nov 26 22:38:39 GMT 2009

One idea for rounding at that level:

Most annoying is that rectangles that are buildings aren't rectangles anymore after rounding. As the OSM data in itself probably isn't accurate at the 2 m level perhaps we could do "tweak" the coordinates so that rectangles stay rectangles (I know, the projection has an influence as well)? This would make the maps much better looking.

Any thoughts about that?


Am 26.11.2009 um 11:47 schrieb Johann Gail:

> Felix Hartmann schrieb:
>> Mark Burton wrote:
>>> Hi Felix,
>>>> Could the DP Filter not remove any points at resolution=24?
>>> It doesn't do anything at that res.
> At the moment it does nothing, but I'm not sure, if it SHOULD do 
> something at this level, as there may be well some points to delete.
>>> Yes, the reason is that the coordinates round to approx the nearest 2m.
>>> We can't do anything about that, it's what Garmin support.
>> okay I see. So the only real solution would be to have intelligent 
>> filters moving the nodes to nearest 2m in such a way that there is 
>> minimal loss of detail. Probably pretty CPU intensive and a lot of work.
>> So we have to live with it, in most places there is no real loss of 
>> information anyhow.
> I have thought of some ways to merge the rounding filter and the dp 
> filter for this reason. Mabe the dp filter should take into account the 
> distance to  rounded coordinates, not the real one. Or maybe it would be 
> better to insert the rounding filter AFTER the dp filter. It may be 
> possible to achive a little improvement, but I doubt it.
> The main reason is the limitation of resolution to 2m.
> Regards,
> Johann
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