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

Thu Nov 26 10:47:00 GMT 2009


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