At 11:18 AM 1/25/5, hmrupp wrote: >Odd that this capability has not been added so far. The lack of lod- >support is almost a knock-out criterium in my eyes. I mean what's the >big deal about having the graphic rendered on the client side if you >cannot easily some into and out of details? >It certainly makes SVG much less usefull for mapping applications.
Hmm, but it's still a hard problem technically. Think about it for a moment, using as an example the coastline of a map of Denmark: At low level of detail you might include coordinates for Skagen, Grena, Vejle, Tondor, Esbjerg, and Hanstholm. This gives the general shape of the coastline. Now, assuming you don't want to download *all* possible data before seeing anything, these coordinates would likely be at the head of a long file, or in a discrete file of their own. Zoom in a little, and you'd want to add Randers between Skagen and Grena, Ebeltoft between Grena and Vejle, and so on. You can either send this second level-of-detail as a file in its own (similar to how zoom-in 2D maps like Yahoo! Maps work today), or send just the new data, while meanwhile sending info on how it relates to the prior data. The more you zoom in, then either (a) the more prior data you're duplicating; or (b) the more data you have to transfer describing how new data relates to prior data. (This relationship data can become quite complex when dealing with concavity.) 3D models may have things a bit easier, because surface-modeling techniques usually don't have the unpredictable concavity and holes we find in real world coastlines. IBM uses Delaunay compression in its multi-resolution mesh surfaces, for instance: http://www.intel.com/cd/ids/developer/asmo-na/eng/segments/44005.htm?page=5 So... are you thinking you'd like to transfer all the data upfront and then selectively display parts of it, or would you rather have the full dataset be transferred in pieces for on-demand viewing...? jd John Dowdell, Macromedia Developer Support, San Francisco (Best to reply on-list, to avoid my mighty spam filters!) Technotes: http://www.macromedia.com/support/search/ Technical daily diary: http://www.macromedia.com/go/blog_jd ----- To unsubscribe send a message to: [EMAIL PROTECTED] -or- visit http://groups.yahoo.com/group/svg-developers and click "edit my membership" ---- Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/svg-developers/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
