pixel distance

[renevoorburg]

If we simplify a line, we usually do it for plotting the line on a map. This means that ideally, we would like to express the tolerance in terms of pixels on the map, not in kilometers. Since maps usually use the Mercator projection, there is not a simply linear correlation between the two.

So if accuracy is a concern, we would add a pixel-distance calculation. Otherwise, we could simply use the degrees to calculate a 'degrees distance' (perhaps with a crude cos(lattitude) correction, as to speed things up.