[mkgmap-dev] [PATCH v1] fix overview bounding box rounding

Mon Jan 25 19:48:38 GMT 2010


On 25.01.2010 20:43, Mark Burton wrote:
> Felix,
>
>    
>>> If you're referring to the fact that the overview map does not match
>>> the bounding box of the map itself, that's because the tile's bounds
>>> are not rounded in the same way as the overview bounding box (lons
>>> rounded down, lats rounded up (at zoom level 13?))
>>>
>>>        
>> Well that is exactly what I was referring to. The problem is that if I
>> place POI at the very left, they are not visible in Mapsource (when
>> zooming in). Maybe the overview map should be rounded to be bigger than
>> the tile below?
>>      
> No, I don't believe so. Making the overview map big is what we do now
> (round out in both lat and lon) but I believe that's wrong because if
> you round like that, all the overview map rectangles get bigger and then
> they overlap which (I believe) is what causes the mousing to fail in
> mapsource. I currently think that both the map boundaries (as
> set by splitter or bounds element) and the overview map bounding box
> have to be rounded the same as I am trying to do with this patch (lons
> rounded down, lats up).
>
>    
>> Some time ago (about 6 month) in the east of Austria Geofabrik cuts, it
>> happened that some part of the map got dropped. Since quite a few time I
>> could not find such problems anymore with real osm data, only with my
>> "testmap".
>> The thing is, that gmaptool to create mp, and maptk to compile it, get
>> the rounding right (or so much better that no more error is visible).
>>      
> Yes, but what's the resolution of that overview map? We currently use
> 13 (I think) but it doesn't have to be so low (just lower than the
> resolution of the tiles).
>    
13/12. And my map ends at 17. I just changed for 15, then 13 fits well. 
With map ending at 17 and overview map being 13 it is not ideal. 
maptk/gmaptool use 2 lower, meaning 15/13 in case lowest map level is 
17, or 14/12 if maps has last objects in 16. Well in general I think we 
need a non empty background map anyhow, because with the basemap on GPS 
resolutions 17 and lower make not much sense, and in Mapsource 6.13 it 
is much faster (one file instead of seeking through all). Also for 
QlandkarteGT non empty overview maps would be much faster. Once overview 
map is not empty, those problems should be gone anyhow.
> Mark
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