[postgis-users] Points or boundaries more efficient for querying?

[Guido Lemoine]

Nick,

If tile boundaries are implicit (i.e. fixed by your choice of tiling grid
and spacing), there is no need to store and or query tile outlines at all.
Have a look at how WorldWind, Google and Virtual Earth do this. VE
is actually VERY cool at this (cooler than GE!). They even provide the
code.

I came across some OSgeo specs on this as well
 (http://wiki.osgeo.org/index.php/Tile_Map_Service_Specification)
Thinking about implementing this sometime soon.

GL


Nick Bower wrote:

>Hello.
>
>We have large quantities of satellite metadata that we will reduce to a
>set of standard tiles covering a large global region of interest.  We
>are doing this because storing the data at native resolution will mean
>an enormous amount of irregularly located data to query later.
>
>We are to spatially query the data; eg give me the tile corresponding to
>my location, and then, give me records for this location corresponding
>to my metadata criteria (ok normally this would be a join on a single
>query I guess).
>
>So what, is the most efficent way to represent the geometry information
>(the tiles); as centre points or tile boundaries?  I initially thought
>points and queries using minimum distance would be least redundant, but
>then the rtree documentation seemed to point to using regions,
>boundaries and contains/intersects type queries would lead to better
>index performance.  Is this the case?  The tiles will of course be
>regular and adjacent.
>
>Ta, Nick
>  
>

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