[josm-dev] Optimizations for larger data sets

Frederik Ramm frederik at remote.org
Sat Dec 8 19:06:22 GMT 2007


Hi,

>>    5. Rewritten MergeVisitor to avoid O(N^2) algorithm.
>>       Otherwise updating a window from the server takes looong
>>       time and you'd like to do such an update before you push
>>       your few-days-old-snapshot based changes back to the server.

Gabriel, haven't you done something in the MergeVisitor a few days ago?

>>   *) Keep precomputed bbox of complete ways:
>>      This allows faster painting of ways both in close-zoom (you filter out
>>      the complete way quickly if it is off-screen) and wide-view (you filter
>>      out/dot-replace small ways) cases.
> 
> Frederik has been talking about adding a "presentation layer" for some while
> now.  That would presumably include a better representation for drawing.

Yes, sadly I haven't done a thing yet but it has always been my plan to 
add an extra layer of objects above the current data objects, and to 
keep display caching stuff in these. That would require a good deal more 
memory but I would avoid cluttering the OSM data objects with stuff like 
indexes and bounding boxes. But I'm open to other suggestions.

Bye
Frederik





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