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[mkgmap-dev] Include the following patches into trunk -- Patch4 - decrease douglas peucker error

From Johann Gail johann.gail at gmx.de on Thu Mar 3 20:54:34 GMT 2011

Okay I've done some comparisons between the two approximations.
>>> For polygons the old version is much better because the patched version
>>> creates bad artifacts. For streets at resolution 23 (if used) to 21 I
>>> prefer it too. At resolution 20 I am indifferent and cannot really
>>> decide what is better. However from 19 to x the  approach as given by
>>> the patch is far superior (drawing speed on GPS much higher, actually
>>> using the normal DP filter maps become more or less unusable for
>>> resolution 16,18 or 19 on etrex).
>>> Can someone see how this behaviour could be implemented for lines only
>>> from resolution 20 or 19 downwards, while keeping the current approach
>>> of the DP filter for the rest?
>> Thanks for intensively testing my old patches and the propose for them
>> being checked in.
>> Glad to see them work fine and beeing useful. :-)
>> I have looked at this patch again. I think your proposal of switching
>> between them at a given resolution is a good one. This should preserve
>> the accuracy at higher zooms and compress the data at lower zooms.
>> Should be worth a try.
>> I'm sorry, but at the moment I have no toolchain ready for compiling
>> mkgmap and preparing patches. If I find the time, I will look into it
>> the next days.
> Okay great. Hope it's not too difficult to change the behaviour to get
> the best of both. I think actually at resolution 20, the "straight"
> patched behaviour should already be used for all lines.
Here is a patch which enables the straightening only at resolution level 
20 and below. This is for testing purposes only! :-)
Before checking it in, it needs a option to set the resolution at which 
this behaviour changes. I expect, not all people at the list will find 
it their taste matched... ;-)


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