[mkgmap-dev] rendering roundabouts

Fri Dec 3 20:42:57 GMT 2010

On Fri, Dec 03, 2010 at 06:51:44PM +0100, Johann Gail wrote:
>If you use the option reduce-point-density then the line is 
>straightened using the douglas peucker algorithm. All segments between 
>two endpoints or T-crossings are straightened. The points of crossings 
>are not touched. Find a description of the algorithm at wikipedia.
>
>http://de.wikipedia.org/wiki/Douglas-Peucker-Algorithmus

Is the mkgmap implementation of the algorithm aware of the Garmin map 
grid? Should it be?

I just noticed some jagged lines on this straight way, and recompiling 
with reduce-point-density does not help. I seem to remember that the 
Douglas-Peucker algorithm would not be applied on the closest zoom level 
(resolution 24). Is that correct? Here is the way in question:

http://www.openstreetmap.org/browse/way/37837385

The problem is caused by the role=vehicle nodes that I added next to the 
bus stops:

http://www.openstreetmap.org/browse/node/616855877
http://www.openstreetmap.org/browse/node/616855878

These nodes should simply be removed. Could the Douglas-Peucker 
algorithm simply use a tighter error bound on resolution 24?

	Marko