[mkgmap-dev] Overview map: tiny patch/review series

Wed Jun 17 19:36:42 BST 2009

>> Hi Elrond,
>>     
> [...]
>   
>> The problem of distorted polygons does not only appear in the overview  
>> map, it appears at all zoom levels.
>>     
> [...]
>
>
> Hi,
>
> Okay, about the DP code, I have some speculation, why it
> performs bad. It's a variation on what happens for the
> overview map in general.
>
> Rounding.
>
> Okay, let me make up an example.
>
> [...]
> The distance of b to a->c is sqrt(2)/2 (0.707), so more
> than unit/2.
>
>
>   
Yes, I think this could be very well the problem. I don't know at the 
moment how the coorinates are rounded at higher shift levels, but this 
could be a very well explanation.  If this is the case, it would 
explain, why it occurs at all shift levels.

Get the coordinates rounded to bit size before or after the DP filter?

Regards,
Johann