[mkgmap-dev] overview2 branch -- sea not rendered at resolution 12

Wed May 8 13:58:20 BST 2013

No, they are already missing.
---Changing --min-size-polygon=12 to --min-size-polygon=1 and they 
appear. I think the problem is the size of the sea tiles as they are cut 
down into smaller polygons by mkgmap itself - because in the input data 
they are big enough... However therefore I tried around all min-sizes 
regarding the resolution to see what works!

So here is a list of the biggest min-size-polygon usable currently:
1=good for resolution 10...
2=good for resolution 11, variable output on resolution 10
3=good for resolution 12, variable output on resolution 11
4=good for resolution 12, nearly no output on resolution 11
5=good for resolution 13, variable output on resolution 12, no more 
output on resolution 11.
6=good for resolution 13, variable output on resolution 12
7=good for resolution 13, variable output on resolution 12
8=good for resolution 13, nearly no output on resolution 12
9=good for resolution 14, variable output on resolution 13
10=good for resolution 14, variable output on resolution 13
11=good for resolution 14, variable output on resolution 13, no more 
output on resolution 12..
12=good for resolution 14, variable output on resolution 13, no more 
output on resolution 12..

The strange thing about this is, that the sea in the input data is large 
enough - I think the problem happens when splitting for subdivisions...

Overview2 branch - before multiple level overview map -- 
min-size-polygon=12 was fine. GpsMapedit says the resolution is 13. I 
assume the min-size was not respected because the input data just got 
carried forward from the last level in the maps - (and 
--min-size-polygon=12 worked fine for resolution 14!)?
In that case mkgmap overview2 should take the following min-sizes - no 
matter what is actually defined:

max min-size by resolution:
1- resolution 10 or lower (10 is working still in Mapsource, dunno about 
9 or lower - I think not)
2- resolution 11
3- resolution 12
6- resolution 13
12- resolution 14
24- resolution 15
48- resolution 16
96- resolution 17
192-resolution 18
..... don't think anything that high makes sense, but better continue 
upwards so it causes no problems. As the results are not really 
consistent - I would rather take 3 for resolution 12, and not 4 - as 
maybe closer/further away from the equator results may differ a bit!
Theese values above, are definitely safe - I never saw missing see 
anywhere worldwide while using- min-size-polygon=12 at resolution 14...

On 08.05.2013 07:51, GerdP wrote:
> Hi Felix,
>
> do you see the see in the ovm_*.img files? If yes, the problem is in the
> part that reads back these files.
>
> Gerd
>
>
> Felix Hartmann-2 wrote
>> On 08.05.2013 02:15, Gerd Petermann wrote:
>>> Hi all,
>>>
>>>> Well, I first thought it would be a Mapsource/Basecamp bug, but
>>> actually
>>>> mkgmap overview2 is not rendering the sea tiles down to resolution 12.
>>>> The lowest resolution working is resolution 14... -- at 13 some sea is
>>>> rendered, at 12 no sea at all is rendered. I think unlike in my earlier
>>>> reply to Henning - that this is some internal bug (maybe related to
>>> that
>>>> before 13 was the resolution of the overview map)
>>> I assume the polygons generated by SeaGenerator are too small, means,
>>> they are all filtered
>>> in the low resolution levels. Maybe we can implement a merge-polygons
>>> function to solve this
>>> problem. Anyway, this is probably not directly related to the overview
>>> stuff.
>> that's what I first thought too. But then I looked at a map created with
>> the same settings using the old overview2 branch (before multiple
>> levels) - which was done at resolution 13. And there no sea at all was
>> missing - while now at 13 it is mostly gone. So I guessed that there
>> must be some other problem...
>>>> Else I really think that the branch can be merged. It is really working
>>>> well now... - and I played around a lot with it.
>>> :-)
>>> Please post a diff for the default style (or a zip file containing all
>>> files). I do not fully
>>> understand the changes.
>>>
>>>> Only other thing is maybe to have an option to delete / not delete the
>>>> ovm*.img files after creation.
>>> Yes, I think an option is ok. I prefer to have the files as it helps
>>> debugging.
>>>
>>>> Resolution 12 is great for continent maps like Europe (not fully needed
>>>> - 14 could do), or Asia (13 is a must, 12 would be much better).
>>> Please place that knowledge as a comment in the style options file.
>>> Maybe you can also add something to the doc files?
>>>
>>> Gerd
>>>
>>>
>>>
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>
>
>
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