Hi, On 7 Oct 2005 at 10:38, Matthias Basler wrote:
> Quick question: Can one geometry be reused in multiple features? If > not, the geometry could simply hold a back reference to it's parent > feature. It seems that WFS allows for Geometry IDs and Geometry reuse. This is quite similar to the concept of "Level 0" in GDF specification, a pure geometric level to which the Features make reference (in GDF with many to many relationships) for defining their geometries. Well, I don't personally like this approach. I think that a Geometry is an attribute, an ID is an attribute, thus a Geometry plus an ID makes a Feature. ;o) Maybe if we plan to build something independent from feature model, we should think of an abstract getID() method which can be implemented to get the Feature FID or another kind of ID for our geometry or topology object. > So my attitude is: I find direct references more intuitive and > quicker, but there might be constraints (like streaming) that might > make the ID approach unavoidable. Sure. > However IDs always need an explicite > "lookup" mechanism, be it a simple Hashmap or something more > sophisticated. I have no experience how much this slows down things > like drawing in large datasets. > What's your opinion and experience on that? I used a TreeMap for ID lookup and a Quadtree as geometric index in my experimental graph application (uses org.geotools.graph objects), I used it to create references between GPS points and the road network (dynamic segmentation), processes around 200 points per second, but never used it for rendering - it's a server-side app. I think I'll collect all the ideas expressed through the mailing list and put them in the wiki. Cheers Sig ------------------------------------------------------- This SF.Net email is sponsored by: Power Architecture Resource Center: Free content, downloads, discussions, and more. http://solutions.newsforge.com/ibmarch.tmpl _______________________________________________ Geotools-devel mailing list Geotools-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/geotools-devel
