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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 20:56:04 GMT 2011

Am 03.03.2011 21:54, schrieb Johann Gail:
> 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... ;-)
> Regards,
> Johann
To tired to remember attaching the patch....

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