Обсуждение: Radial searches of cartesian points?
Hi, I have a data set of several hundred thousand points. Each point is saved as a three dimensional coordinate, i.e. (x, y,z). What I'd like to do is given a point in that space, get a list of all of the points in the table within some radius. I'm familiar with the q3c package that does this for points that lie on a sphere, but is there something comparable for radialsearches on 3D cartesian points? Speed is definitely an issue given the number of points I have. Thanks for any suggestions! Cheers, Demitri
On Thu, Jan 5, 2012 at 11:01 AM, <thatsanicehatyouhave@mac.com> wrote: > Hi, > > I have a data set of several hundred thousand points. Each point is saved as a three dimensional coordinate, i.e. (x, y,z). What I'd like to do is given a point in that space, get a list of all of the points in the table within some radius. > > I'm familiar with the q3c package that does this for points that lie on a sphere, but is there something comparable forradial searches on 3D cartesian points? Speed is definitely an issue given the number of points I have. > > Thanks for any suggestions! see: http://www.postgresql.org/docs/9.1/interactive/cube.html and pay special attention to gist indexing portions. cube only indexes box operations, but you can cull the sphere using 3d distance formula for points between inner and outer bounding cube. merlin
Hi, On Jan 5, 2012, at 12:54 PM, Merlin Moncure wrote: > see: > http://www.postgresql.org/docs/9.1/interactive/cube.html > > and pay special attention to gist indexing portions. cube only > indexes box operations, but you can cull the sphere using 3d distance > formula for points between inner and outer bounding cube. Thanks for the pointer, Merlin. I had been looking at that, and the bounding boxes idea is good. I'm a little concerned aboutthe very large number of trigonometric calculations this will lead to. For a single, occasional search this would notbe an issue, but I'm going to be performing this search thousands of times. Is anyone aware of a datatype or third-party implementation that will index in three dimensions radially, or what it wouldtake to accomplish this? Cheers, Demitri