[OSM-dev] Drawing ways with bezier curves rather thanlinesegments

Frederik Ramm frederik at remote.org
Thu Jan 25 12:45:36 GMT 2007


> I think this should be investigated a bit more closely. Patents can  
> end up being quite specific, so it may well be possible to use  
> beziers in a way that isn't covered by their patent. Also I suspect  
> that knowing the US patent office, there are scores of other things  
> we are already doing that could be covered by somebody's patents....
It seems to me that these patents only apply to storing data as  
Bezier curves in order to reduce the amount of data. This is an  
interesting topic which I think should be investigated by us (I  
believe I have already mentioned storing the position of Bezier  
control points as node attributes a few weeks ago in another post),  
because we could actually throw away a lot of those segments that are  
just put in as an approximation of a curve. They don't hurt me  
because of the storage space, but they are not satisfactory if used  
to describe curves because they will never be the "real thing", i.e.  
there's always a zoom level at which they are wrong.

But before we do something like that we would have to ensure that  
software working with our data can actually handle curved segments;  
for example, the simple queries posted recently to find out how many  
kilometres of roads we have in our database would not work with curves.

Anyway, what was presented here is a way to use bezier curves  
generated "on the fly" from straight lines during the rendering  
process. I did not see anything about that in the patents mentioned  
(did not read every sentence though...).

Maybe we should file a patent ;-)


Frederik Ramm  ##  eMail frederik at remote.org  ##  N49°00.09' E008°23.33'

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