[mkgmap-dev] Problem in splitter (Africa)

Mon Jan 5 21:14:23 GMT 2015

Hi Stephen,

last year mkgmap failed for a tile in Canada because of 
a special case, see my post:
http://gis.19327.n5.nabble.com/ontario-canada-maps-tp5798080p5798490.html

At that time I changed mkgmap so that it doesn't
generate as many POI for these ways, and maybe later
we also changed the split algo in mkgmap to 
avoid this problem.
I think there is no good reason to use a very small --max-nodes
value when you plan to create a map for a country
or continent. It may be useful for the new devices with only
8 MB on a memory card.

Gerd

steve sgalowski wrote
> in some of the countries i do , if i dont make the node count small , the
> map size exceedds , size limit of 3 gb
> then unshure how , canada has done this ok
> 
> stephen
> 
> 
> On Tue, Jan 6, 2015 at 5:24 AM, Gerd Petermann <

> gpetermann_muenchen@

>> wrote:
> 
>> Hi all,
>>
>> I wonder what splitter should do in this case:
>>
>> Stephen uses paramter --max-nodes=80000
>> and splitter reports
>> "Highest node count in a single grid element is 557,084"
>>
>> It is obvious that at least one tile will have much more than the
>> requested 80.000 nodes,
>> on the other hand, the file africa.osm.pbf contains large nearly empty
>> areas,
>> and that makes it very difficult to find a good split.
>> The current version r416 fails because it doesn't accept tiles with less
>> than 5% of
>> the max-nodes value, so it searches for a solution where every tile has
>> at
>> least 4000 nodes,
>> and that might not exist.
>>
>> I see these options:
>> 1) splitter can continue trying to split the data, accepting almost empty
>> output files
>> (e.g. some with < 5 nodes and very high aspect ratios like 32)
>> 2) if that fails,  splitter can set the max-nodes value to 557,084 and
>> try
>> again
>> 3) or stop with an error message that tells the user that it is not
>> possible
>> to split with the used resolution
>> 4) or restart using a higher resolution  (15 would be required here
>> instead of 13),
>>
>> @Stephen
>> What reason do you have to use such a small max-nodes value?
>> Would it be ok for you to use a higher one?
>>
>> Gerd
>>
>>
>>
>>
>>
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